budding electricians, isolation transformer question

[unsped]

my apartment is from the stoneage and only has 2 prong outlets and the quality of the power is not fantastic. to add some safety i am replacing the 2 prong outlets with 3 prong gfci outlets (only way to add a 3 prong outlet and keep code). which will help with not electrocuting myself but still allows surging to be an issue.

1) my understanding is that i can use an isolation transformer (like a triplite etc..) to protect my 3 prong devices (computer etc..) is this correct?

2)( if the devices plugged into the isolation transformer are turned off the isolation transformer should not draw much current current? it isn't like always drawing max current or anything right?

 

[Paperdoc]

1) Protect from what? If you're worried about very short voltage spikes or drops, there are line conditioners that can help reduce them, but they are certainly more than a simple isolation transformer. For longer-term disturbances like a "brownout" that lasts several minutes, nothing can fix that other than a UPS, and those can get big and expensive if you want to do anything more than give you 5 minutes to shut down in an orderly manner. However, if your concern is that you have no real Ground connected to your computer, neither of those devices will help. A Ground connection does two things. It provides a current path in fault cases where a voltage source shorts out to the chassis. That means both that the chassis itself does not become a high-voltage source causing electrocution, and that the fault will almost certainly pull such a large current that a fuse will blow and shut off power to the faulty device. The second benefit of a Ground is that is helps the case to function as a shield against electrical noise entering from outside the case, and also against noise escaping the case into the surrounding room. To get a Ground for this, you actually need to find or establish a good true Ground source like a buried metal rod, and then you have to run a Ground wire from it to the case of your computer equipment. No transformer or UPS can provide that.

A GFCI is a reasonable substitute for protection against electrocution due to a circuit fault. While it does not provide a Ground, either, the GFCI constantly compares the currents entering and leaving the device being protected, and the MUST be the same. Any mismatch (that is, over 5 mA I think) is treated as proof that current is being diverted someplace wrong and possibly hazardous, and the GFCI "trips" (like a circuit breaker) to shut off the power supply.

2) You are right. With no load on the secondary winding of an isolation transformer, the draw by the primary winding is quite minimal, although not exactly zero.

 

[DrPizza]

What Paperdoc said, plus, if you were to put on an isolation transformer, remember that the GFCI doesn't protect downstream from the transformer.

 

[unsped]

thanks for the info, i actually recognize paperdoc's nick from alot of electronics stuff i am looking up

in this place, the fridge, microwave, washer, dryer, the computer are all on cheater plugs put in by the landlord ... i'm sure this is quite against code but they won't do anything about it i'm sure.

some follow up questions:

1) i guess i have this idea that if there is a lightening strike or something my 3 prong metal case devices might become charged with thousands of volts and just sit there charged and waiting trying to kill me because they can't dump it out to the ground is this realistic?

2) if a 3 prong device does short and energize the casing, will a non grounded gfci trip if i get zapped by the casing?

3) will i be reasonably safe with just replacing them all to ungrounded gfci outlets? (labeling them non functioning ground to be in code)

4) will a ups function ok plugged into an ungrounded gfci outlet, according to cyberpower it should be reasonably safe, but void any warranty.

5) the place only has 1 circuit and when the washing machine is on the lights dim on and off subtlety, is this an issue of no ground? just crappy wiring? any recommendations on things to try?

i will look into trying to get the outlets actually grounded, but it is a rental and run by a slumlord who would rather pay fines than fix things.

i know i am really talking the place up!

 

[edro]

What are you trying to protect from?
Lightening Surges? Get a surge suppressor.

Your devices already have some protection from unstable voltage sources.

Not having a ground wire in your receptacles will not affect your device performance, but can affect their safety.
It is just there as a return path for current if there is an arc to the metal case.

Having an isolation transformer will not make your device any more safe.
If a computer power supply has an arc to the computer case, it will still create a fire unless the isolation transformer has its own fusing.

You are over-thinking this and are just scared about having 2 prong outlets.
Just replace with GFCI and be done.

 

[edro]

thanks for the info, i actually recognize paperdoc's nick from alot of electronics stuff i am looking up

in this place, the fridge, microwave, washer, dryer, the computer are all on cheater plugs put in by the landlord ... i'm sure this is quite against code but they won't do anything about it i'm sure.

some follow up questions:

1) i guess i have this idea that if there is a lightening strike or something my 3 prong metal case devices might become charged with thousands of volts and just sit there charged and waiting trying to kill me because they can't dump it out to the ground is this realistic?

2) if a 3 prong device does short and energize the casing, will a non grounded gfci trip if get zapped by the casing?

3) will i be reasonably safe with just replacing them all to ungrounded gfci outlets? (labeling them non functioning ground to be in code)

4) will a ups function ok plugged into an ungrounded gfci outlet, according to cyberpower it should be reasonably safe, but void any warranty.

i will look into trying to get the outlets actually grounded, but it is a rental and run by a slumlord who would rather pay fines than fix things.

1. No. The white wire (neutral) is already tied to ground at the distribution panel.
2. As soon as you touch the electrified case, some current will flow through you. The GFCI will trip very quickly (hopefully before you die).
3. Yes you will, that is why it is code.
4. Yes it will.

Remember that 2 prong outlets were "to code" for over 50 years. They work fine...

 

[unsped]

What are you trying to protect from?
Lightening Surges? Get a surge suppressor.

my understanding is that ungrounded surge suppressors are nonfunctional

thanks for all the info!

 

[edro]

my understanding is that ungrounded surge suppressors are nonfunctional
thanks for all the info!

Oh yeah, you're right about that... most cheap surge suppressors use MOVs to direct spikes in current to ground.

 

[westom]

my understanding is that ungrounded surge suppressors are nonfunctional

edro said what is important. What are you trying to protect from?

You are confusing human safety with transistor safety. Each anomaly requires different solutions. You are also confusing safety ground with earth ground. Items with similar names are completely different.

Two prong or three? Code is blunt clear about this. If two wire (ie early 1960s or older), then only two wire receptacles or a GFCI is permitted. If three prong receptacles are installed, then you have created a serious human safety issue. That solution also says nothing about protecting appliances (transistors).

All appliances contain major protection. Your concern is a rare transient - maybe once every seven years - that can overwhelm that protection. Such transients must be earthed before entering the structure. Informed homeowners install what has been the solution for over 100 years. One 'whole house' protector connected short (ie 'less than 10 feet') to earth ground. Not safety ground. AC wires inside walls have sharp bends, are too long, have splices, are not separated from other non-grounding wires, and may be inside metallic conduit. A connection to earth ground must be low impedance (ie 'less than 10 feet') to a single point earth ground. Two critical parameters in that sentence. Only one 'whole house' protector does both.

What does a UPS do? It connects an appliance directly to AC mains. No filtering or isolation. Then connects to a battery only when voltage drops excessively. How often does your voltage drop so low that incandescent bulbs dim to 50% intensity? If not, your AC voltage is ideal perfect for all electronics.

Now, motorized appliances dislike and can be harmed by those same voltage variations. If voltage is dropping so low as to cause major light dimming, then a UPS must power appliances at greatest risk: refrigerator, air conditioner, washing machine, and furnace.

However the 'dirtiest' power is created by a UPS in battery backup mode. Power so 'dirty' as to be potentially harmful to power strip protectors and small electric motors. Because a UPS is made as cheap as possible. Does not claim to do what many have posted here. If the UPS did that magic, then spec numbers were posted that define each UPS solution. No numbers will be provided. UPS does not ‘clean’ power. Its one function: to provide temporary and 'dirtiest' power during short blackouts and extreme brownouts.

Neither UPS nor isolation transformer (which is not a UPS) solves the OP's concerns. 1) A GFCI must replace those two wire receptacles for human safety. 2) One 'whole house' protector is the only solution for transistor safety - especially in a house that only has two wire power. 3) That 'whole house' protector is also a least expensive solution. And 4) how it is done in any facility that can never have transient damage - ie munitions dumps.

 

[Mark R]

An Isolation transformer is a method for providing safety of life, in areas which are high risk for electric shock.

The way mains power is supplied is that the power company connects "neutral" to ground, and supplies the "pressure" (voltage) via the live wire. The safety risk here is that if you come into contact with the live wire, and the ground simultaneously, the current can flow through you to complete the circuit.

GFCIs (also called RCDs) detect when current in live and neutral don't match (the assumption being that the live wire must be coming into contact with ground), and shut off the power when this condition is detected. E.g. if I'm running an electric saw, cut through the cable, and pick up the end of the exposed live wire. The GCFI will trigger and shut off the power before the shock has time to cause significant health effects.

Isolation transformers are an alternative method. The transformer creates a new pair of live and neutral wires with no connection to ground (i.e. they are isolated) - the energy is transferred magnetically. If either of those wire comes into contact with ground, no current will flow, as the entire circuit is isolated. In the saw scenario above, if I picked up the live wire, I will receive no shock, as there is no circuit formed through me and the ground.

Isolation transformers have the advantage of simplicity, reliability, the passive nature of the safety (a GCFI must detect an unsafe condition and activate to ensure safety, a transformer is inherently safe) and robustness. So, they are preferable to GCFIs for certain activities - e.g. construction sites (where many countries make isolation transformers a legal requirement for power tools).

Isolation transfers are sometimes also used in hospitals, and other areas where very high power reliability is needed. Metal cased appliances are protected against electric shock, by connecting the chassis to ground. If the live wire comes loose and contacts the chassis, a short circuit will occur causing a fuse to blow, breaker to trip, or GCFI to trip out. In some circumstances, e.g. in a hospital OR, this is unacceptable. By using an isolation transformer, if a live wire contacts a metal chassis (or there is dust/water ingress, etc.), a short circuit will not occur, and power will remain on. Electric shock is prevented because the transformer provides isolation. This ensures that the faulty equipment can be removed, while ensuring that other equipment on the same circuit is not interrupted. Note that in this medical environment, sophisticated monitoring equipment must be connected to the transformer so that in the event of a fault that would normally trip a breaker/GCFI, an alarm will sound to alert staff to the problem.

A common misapprehension is that an isolation transformer protects equipment against voltage surges, swells, etc. Generally, an isolation transformer provides only limited protection. Over voltage conditions, may well be transmitted through the transformer, and low-voltage conditions almost certainly will be. Spikes (e.g. from lightning) may also be transferred through, although they are likely to be somewhat reduced in energy.

The reason that such confusion exists is because there exist "voltage regulating transformers" (also called ferroresonant transformers). These are specially designed transformers, that are designed to provide a constant output voltage, even when input voltage suffers major surges or dips. They are also good at blocking spikes (e.g. from lightning), and cleaning up distorted power due to nearby heavy industrial machinery. They even provide a very short term (about 0.2-0.3 seconds) UPS like function, which permits them to keep supplying power in the event of a short power glitch (e.g. like power being switched from one line to another). These special transformers are frequently called "isolation" transformers, but that is not their main function.

 

[unsped]

thanks for all the input, i wasn't clear about the ups, i would be using that to merely prevents the machine from dying when the breaker occasionally trips (this is the gf's place and the electric heater, rice cooker, microwave etc.. sometime we forget the heater is on and were in the dark). i don't expect the ups to add protection just didn't know if it would be causing more danger.

i think it is clear that i should install the gfci's and call it a day, and that a ups will be ok if my goal is to provide backup power.

the washer and dryer are outside so perhaps the landlord may be willing to run a separate circuit to them to get them off of the circuit all of the lights are on and prevent the dimming issue.

thanks again for all your info, you read alot of scary stuff in some of the forums and it is difficult for the uninformed to accurately gauge the realistic concerns.

 

[westom]

the washer and dryer are outside so perhaps the landlord may be willing to run a separate circuit to them to get them off of the circuit all of the lights are on and prevent the dimming issue.

Dimming often indicates a serious human safety issue. Power cycling of any major appliance should never cause dimming.

A tripping circuit breaker is also a serious issue. Those breakers are equivalent to backup O'rings on the Space Shuttle. If depending on a backup system to avert house fire, then you are asking for consequences similar to the Challenger. Two reasons why your landlord might have to install that separate circuit.

Meanwhile, if an electrician is installing that new circuit, then it is in the landlord's interest and yours to also earth a 'whole house' protector. Installing that protector is cheap. Getting an electrician onsite is the major expense.

 

[bud--]

The best information on surges and surge protection I have seen is at:
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
- "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" .
And also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home"

The IEEE guide is aimed at people with some technical background.

The NIST surge guide suggests most damage is from high voltage between power and phone/cable wires (for instance at TV/related equipment).

When using a plug-in protector (or UPS) all interconnected equipment needs to be connected to the same plug-in protector. External connections, like phone and cable, also need to go through the protector. Connecting all wiring through the protector prevents damaging voltages between power and signal wires.

my understanding is that ungrounded surge suppressors are nonfunctional

Without a ground plug-in protectors still provide surge protection. As explained in the IEEE surge guide (starting page 30), they work primarily by limiting the voltage between all wires (signal and power) and the ground at the protector. That happens even if the "ground" is not connected. They do not primarily work by earthing the surge through the ground wire. However using them without a ground is not a good idea. And particularly not if the phone wires go through the protector.

Two prong or three? Code is blunt clear about this. If two wire (ie early 1960s or older), then only two wire receptacles or a GFCI is permitted. If three prong receptacles are installed, then you have created a serious human safety issue.

It is possible that the wiring system has a ground (like BX) but has only 2 prong receptacles installed. With only one circuit it is not likely (wiring is probably pretty old).

All appliances contain major protection.

A lot of equipment has no surge protection. Not likely much has "major protection".

One 'whole house' protector connected short (ie 'less than 10 feet') to earth ground.

Service panel protectors are a good idea.
But from the NIST guide:
"Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

A service panel protector, by itself, does not limit voltage between power and signal wires.

Does not claim to do what many have posted here. If the UPS did that magic, then spec numbers were posted that define each UPS solution. No numbers will be provided.

Westom always ignores specs that are provided anyway.

Both the IEEE and NIST surge guides say plug-in protectors are effective. So are UPSs that have the same protection added. They are not a great idea with no power wiring ground.

A service panel protector is likely not practical with a slum landlord.

As Mark said, isolation transformers (unless ferroresonant) do not provide surge protection. They are likely rather expensive.

Everyone agrees that GFCIs provide protection from shock. One problem is that they are significantly larger than regular receptacles - they are sometimes hard to get into the box. One possible way to use GFCIs is to put one in a weatherproof box (has no holes) with a cord to a 2-prong plug. That means no electrical work on the building and the GFCIs can leave with the OP if he moves.

There is less equipment that has 3-prong plugs these days. The OP may not need GFCI protection at many locations.

 

[westom]

OP describes a building without safety ground. Two wire receptacles. NIST's page 19 of 24 says what a protector does without a low impedance (ie 'less than 10 foot') connection to earth:

A very important point to keep in mind is that your surge protector will work by diverting the surges to ground. The best surge protection in the world can be useless if grounding is not done properly.

A protector that magically makes energy disappear is "useless". Best called a scam. Protection is always about where energy dissipates. Always. Every facility that can never have damage always has superior earthing. And a protector connected low impedance (ie 'less than 10 feet') to earth. Other protectors that pretend to do protection without earth ground are discussed and then defined by the NIST. Useless.

OP's landlord is unlikely to upgrade receptacle safety grounds. OP's landlord could install the superior and least expensive solution by simply earthing one 'whole house' protector. Only item in his building that must always be earthed - the breaker box - is also where the world's best protector is installed. The superior solution costs about $1 per protected appliance. So that energy (even direct lightning strikes) dissipates harmlessly outside the building. Does not go hunting for earth destructively via appliances.

IEEE makes recommendations in standards. IEEE Standard 142 entitled 'Static and Lightning Protection Grounding' defines one 'whole house' protector:

Still, a 99.5% protection level will reduce the incidence of direct strokes from one stroke per 30 years ... to one stroke per 6000 years ...

Damning numbers. If upgrading any breaker box connections, then a best solution is to also earth a 'whole house' protector. Because the only solution in homes with two wires is also so inexpensive. Because no other solution is as effective.

 

[bud--]

NIST's page 19 of 24 says what a protector does without a low impedance (ie 'less than 10 foot') connection to earth:

Everyone is in favor of earthing electrical systems.

What does the NIST surge guide really say about plug-in protectors?
They are "the easiest solution".
And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

A protector that magically makes energy disappear is "useless".

It is only magic for westom.

It is easy to explain where surge energy goes, if anyone is interested. The amount of energy that can make it to a plug-in protector is surprisingly small.

Best called a scam.

Westom thinks plug-in protectors are a scam. He googles "surge" to find places to post in his crusade to stamp out the scourge of plug-in protectors.

Other protectors that pretend to do protection without earth ground are discussed and then defined by the NIST. Useless.

Poor westom has a disability that prevents him from seeing anything that does not conform to his beliefs.

Both the IEEE and NIST surge guides say plug-in protectors are effective. For instance, the IEEE surge guide has only 2 examples that detail surge protection. Both use plug-in protectors.

Read the sources - excellent information.

OP's landlord could install the superior and least expensive solution by simply earthing one 'whole house' protector.

The OP's landlord could also supply free beer.

IEEE makes recommendations in standards. IEEE Standard 142 entitled 'Static and Lightning Protection Grounding' defines one 'whole house' protector:

The IEEE Emerald book ("IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment") recognizes plug-in suppressors as an effective protection device.

If upgrading any breaker box connections, then a best solution is to also earth a 'whole house' protector.

Repeating from the NIST surge guide:
"Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

Service panel protectors are very likely to protect anything connected to only power wires. They do not, by themselves, limit voltage between power and signal wires, and equipment connected to both power and phone/cable/... wiring is not necessarily protected. The NIST surge guide suggests most equipment damage is from high voltage between power and signal wires. An example is in the IEEE surge guide starting page 30. (And in that example a power service protector would provide no protection.)

 

[westom]

What does the NIST surge guide really say about plug-in protectors?
They are "the easiest solution".

And can make appliance damage easier. And must be protected by a 'whole house' protector. And does not claim to protect from typically destructive transients (as demonstrated by all those manufacturer spec numbers). And do not connect to earth ground. And does nothing to address any of the OP's questions.

bud is promoter for plug-in protector manufacturers. A $4 power strip with ten cent protector parts sells for $45 or $120. bud's job is to protect those obscene profits margins. By posting nothing relevant to the OP.

bud has a nearly one decade history of following me everywhere to post disparaging posts. He is paid to do this; to promote protectors that do not even claim to protect from typically destructive surges. That have a history of creating house fires.

The OP has receptacles without safety grounds. So why is bud posting? Because it is his job to follow me everywhere and make discussion nasty. To promote protectors that do nothing for the OP. To promote protectors that must never be installed when safety ground does not exist.

Protection in every facility that cannot have damage is always about dissipating energy harmlessly outside buildings. Always. An employee in a telco switching center could even get fired for installing what bud recommends. Standard in commercial radio stations, telephone and mobile communication facilities, military bases, and even in munitions dumps is the best and only solution for the OP. That, however, will not pay bud's salary. So bud will post incessantly about a device that provide nothing for the OP. That must not be installed when using two wire circuits.

OP has two wire receptacles. Best solution for three prong appliances is a GFCI - as defined by code in articles 406.3(D)(1), (2), and (3). GFCI is another electronic device that can only be protected by a properly earthed 'whole house' protector. If upgrading one circuit to eliminate dimming or breaker tripping, then a ‘whole house’ protector should also be installed.

 

[0roo0roo]

edro said what is important. What are you trying to protect from?

You are confusing human safety with transistor safety. Each anomaly requires different solutions. You are also confusing safety ground with earth ground. Items with similar names are completely different.

Two prong or three? Code is blunt clear about this. If two wire (ie early 1960s or older), then only two wire receptacles or a GFCI is permitted. If three prong receptacles are installed, then you have created a serious human safety issue. That solution also says nothing about protecting appliances (transistors).

All appliances contain major protection. Your concern is a rare transient - maybe once every seven years - that can overwhelm that protection. Such transients must be earthed before entering the structure. Informed homeowners install what has been the solution for over 100 years. One 'whole house' protector connected short (ie 'less than 10 feet') to earth ground. Not safety ground. AC wires inside walls have sharp bends, are too long, have splices, are not separated from other non-grounding wires, and may be inside metallic conduit. A connection to earth ground must be low impedance (ie 'less than 10 feet') to a single point earth ground. Two critical parameters in that sentence. Only one 'whole house' protector does both.

What does a UPS do? It connects an appliance directly to AC mains. No filtering or isolation. Then connects to a battery only when voltage drops excessively. How often does your voltage drop so low that incandescent bulbs dim to 50% intensity? If not, your AC voltage is ideal perfect for all electronics.

Now, motorized appliances dislike and can be harmed by those same voltage variations. If voltage is dropping so low as to cause major light dimming, then a UPS must power appliances at greatest risk: refrigerator, air conditioner, washing machine, and furnace.

However the 'dirtiest' power is created by a UPS in battery backup mode. Power so 'dirty' as to be potentially harmful to power strip protectors and small electric motors. Because a UPS is made as cheap as possible. Does not claim to do what many have posted here. If the UPS did that magic, then spec numbers were posted that define each UPS solution. No numbers will be provided. UPS does not ‘clean’ power. Its one function: to provide temporary and 'dirtiest' power during short blackouts and extreme brownouts.

Neither UPS nor isolation transformer (which is not a UPS) solves the OP's concerns. 1) A GFCI must replace those two wire receptacles for human safety. 2) One 'whole house' protector is the only solution for transistor safety - especially in a house that only has two wire power. 3) That 'whole house' protector is also a least expensive solution. And 4) how it is done in any facility that can never have transient damage - ie munitions dumps.

Well, online ups are clean..
but cost $$$

 

[bud--]

And can make appliance damage easier.

Not if wired correctly. But westom can not figure out how they work.

And must be protected by a 'whole house' protector.

Complete nonsense.

With no service panel protector, the amount of energy that makes it to a plug-in protector is surprisingly small, even with a very strong very near lighting strike to power wires.

And does not claim to protect from typically destructive transients (as demonstrated by all those manufacturer spec numbers).

More complete nonsense. A plug-in protector with high ratings and wired correctly is likely to protect from a very near very strong lightning strike. That is why some of them can have a protected equipment warranty.

And do not connect to earth ground.

Westom's believes that surge protection must directly earth a surge. Plug-in protectors are not well earthed, so westom believes they can not possibly work.

Unfortunately for westom, the IEEE surge guide explains (starting page 30) that plug-in protectors do not work primarily by earthing surges. They work by limiting the voltage between all wires and the ground at the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment. Read the source.

And does nothing to address any of the OP's questions.

A plug-in protector downstream from a GFCI is one possible scheme. There is not a good way to provide protection for the OP.

bud is promoter for plug-in protector manufacturers.

If westom had valid technical arguments he wouldn't have to lie. The only association I have with surge protection is I am using a couple protectors.

A $4 power strip with ten cent protector parts sells for $45 or $120.

One of the plug-in protectors I am using has 3 MOVs with a rating of 590 joules each, 1770 joules total Provide a source for a 590 joule MOV for $0.10.

The major brand protector did not cost anywhere near $45. But westom only buys from Monster.

By posting nothing relevant to the OP.

I posted comments on each protection scheme. There is not a good solution for the OP.

bud has a nearly one decade history of following me everywhere

That would take a time machine. I first saw westom much more recently when he repeatedly posted his nonsense in a short time on a couple newsgroups I follow.

One of them was an electrical engineering forum. The other major participant agreed with me. Westom mischaracterized the views of researcher Arshad Mansoor and provoked a response: "I found it particularly funny that he mentioned a paper by Dr. Mansoor. I can assure you that he supports the use of [multiport] plug-in protectors. Heck, he just sits down the hall from me. LOL."

Westom similarly mischaracterizes the views of the IEEE and NIST here.

But westom has been compulsively posting this drivel for 10 years??

to post disparaging posts.

Westom is "disparaged" by the IEEE and NIST.

The OP has receptacles without safety grounds. So why is bud posting? Because it is his job to follow me everywhere and make discussion nasty.

Westom thinks the IEEE and NIST are nasty.
(But it is not nasty to call someone a company stooge?)

For real science read the IEEE and NIST surge guides - excellent information from reliable sources. Both say plug-in protectors are effective.

Then read the sources that agree with westom that plug-in protectors are NOT effective - there are none.

 

[edro]

ok, now I am starting to get confused.
westoms posts are rambling on...

 

[Mark R]

One of the plug-in protectors I am using has 3 MOVs with a rating of 590 joules each, 1770 joules total Provide a source for a 590 joule MOV for $0.10.

The major brand protector did not cost anywhere near $45. But westom only buys from Monster.

Surge protector "energy" ratings are not additive. Only 1 surge diverter will ever fire at a time.

It doesn't matter whether you have 3 or 10 or 100 varistors built into a surge protection device. Only the most sensitive one will fire, and if the energy released by clamping the surge exceeds it's capacity, it will be incinerated. This is the case even when using "binned" varistors - the variation within a single bin will typically result in 1 varistor taking 99.9% of the surge energy, even when paralleled with multiple "matched" varistors.

Of course, the "surge energy" rating of a surge protector isn't really that useful a measure, as it is an aggregation of all the more important parameters of the protector: namely surge diversion current, maximum surge duration and clamping voltage.

The surge energy isn't actually dissipated by the protector - it is diverted away from the protected device. This means that the actual amount of surge energy that can be protected against is much higher than the rating of the protection device.

 

[LiuKangBakinPie]

my apartment is from the stoneage and only has 2 prong outlets and the quality of the power is not fantastic. to add some safety i am replacing the 2 prong outlets with 3 prong gfci outlets (only way to add a 3 prong outlet and keep code). which will help with not electrocuting myself but still allows surging to be an issue.

1) my understanding is that i can use an isolation transformer (like a triplite etc..) to protect my 3 prong devices (computer etc..) is this correct?

2)( if the devices plugged into the isolation transformer are turned off the isolation transformer should not draw much current current? it isn't like always drawing max current or anything right?

If you want to protect your equipment you use a surge protector/suppressor. The size of it will depend how far from the entry the devices are. If its more to the back of the house you can fit a smaller cheaper one. I always place one at the Db and a smaller one back. Another habit I have of doing is to tie 3 knots in the cables of my devices like the psu cable etc etc

Safety regulations require that an isolation transformer is only allowed to isolate the hot and neutral wires; the grounding wire must be passed straight through. Since the computer circuits including data communication circuits are connected to the grounding wire and not the neutral wire, the isolation transformer or any power conditioner or UPS with an isolation transformer has absolutely no affect on computer grounding problems. The neutral wire is associated with many misunderstandings and myths related to power quality. In fact, the neutral wire and the hot wire are interchangeable from the point of view of protected equipment

 

[westom]

ok, now I am starting to get confused.

What is so confusing? Only component required in every protection system is earth ground. Some protection systems have no protector. But every protection system always connects to where hundreds of thousands of joules dissipate. Only item 'always' required is earth ground. A fact repeated often because advertising encourages confusion. bud's job and nasty posts are to keep you confused with lies, half truths, disparaging remarks, and no spec numbers.

Many think of protection in terms of a protector. No protector does protection. Either a surge is connected to earth via a wire (ie cable TV, satellite dish). Or a protector makes the same earth connection (telephone, AC electric). A wire or protector does the same thing. Connect hundreds of thousands of joules to what does the protection.

OP's only solution connects hundreds of thousands of joules harmlessly to earth via a ‘whole house’ protector. Effective solution – one ‘whole house’ protector - starts at 50,000 amps so that direct lighting strikes cause no damage. Effective protector is defined by amps - the connection. Joules is about where energy dissipates – in earth ground.

Why is that confusing? Because you do not understand some basic electrical concepts. A safety ground is not earth ground. Wire is electrically different at both ends. A 50 foot romex to the breaker box would be less than 0.2 ohms resistance. And something like 120 ohms impedance. A tiny 100 amps surge on a wall receptacle puts that receptacle at something less than 12,000 volts. Please understand relevant electrical concept you have not yet learned - impedance.

For example, a 200 watt transmitter puts voltages on a long wire antenna. Touch one part of that antenna to feel 0 volts. Touch another part of the same wire to be shocked by over 100 volts. Why two completely different voltages on the same wire? Electrical concept (impedance) also says why a wall receptacle safety ground is not earth ground. If you do not learn these electrical concepts, then you may become confused. Even assume a neutral wire provides earth ground. Impedance says why a wall receptacle safety ground is not earth ground. I believe you did not know any of this. Get angry rather than say what has you so confused. Nothing in a wall receptacle is earth ground.

OP has two wire receptacles. A serious human safety threat exists if using plug-in protectors on two wire circuits.

First, the OP has two wire circuits. Earthing a 'whole house' protector is his only solution. That does transistor safety.

Second, for human safety on three prong appliances, the OP must upgrade receptacles with a GFCI - as defined by the National Electrical code.

 

[LiuKangBakinPie]

A typical lightning strike consists of 20,000 to 100,000 amps at 30 million volts

Lightning isn’t the only source of electrical surges. Many the Home devices that are sensitive to electrical surges also produce electrical surges. Motor driven equipment, such as garage door openers, refrigeration, and air conditioners are not the only sources of electrical surges within the home. Television,computers, microwave ovens, and modern gas ranges and furnaces that use electronic ignition can also cause line disturbances and surges.

There is a common misperception that larger surge amplitudes deposit more energy into a SPD. IEEE research shows this is not the case. Energy deposited into MOVs actually decreases as surge intensity reaches certain levels. Therefore, Joule ratings are misleading. The surge industry’s technical community avoids Joule ratings in this context.

Energy is defined as Power x Time. How are Power and Time defined and where are Watts actually going?

Another example, can the SPD sustain a Joule rating many times, one time, or does it define failure? At least one manufacturer uses a multiplier. For example, if an MOV is rated 1J, but can withstand 5,000 hits, the SPD is rated 1J x 5,000 = 5,000 Joules. In summary, Joule ratings are not recognized by surge suppression Standards.

Read this IEEE white paper titled, “No Joules for Surges: Relevant and Realistic Assessment of Surge Stress Threats”

Read this as well
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf

 

[westom]

There is a common misperception that larger surge amplitudes deposit more energy into a SPD. IEEE research shows this is not the case. Energy deposited into MOVs actually decreases as surge intensity reaches certain levels. Therefore, Joule ratings are misleading.

Joules is a ballpark number that defines a protector's life expectancy over many surges. For example, one MOV manufacturer defines testing for MOV degradation:

The change of Vb shall be measured after the impulse listed below is applied 10,000 times continuously with the interval of ten seconds at room temperature.

If the MOVs are properly sized, then MOVs do not degrade for decades (ie 10,000 transients).

What happens when a protector has more joules? It absorbs less energy. A protector is only a connecting device when something better - wire - cannot make that connection to earth. No low impedance earth connection means a protector is ineffective.

BTW, lightning only has voltage where that connection to earth is inferior. Superior protection (ie a wire) means 20,000 amps to earth with near zero voltage. High voltage only exists when someone foolishly tries to stop, block, or filter a surge. And near zero voltage when properly connected to earth. Best parameter for a protector is amps; not joules.

A minimal 'whole house' protector starts at 50,000 amps.

Hopefully this restates what you were saying.

Again, topic is the OP's building with only two wire circuits. His only viable transistor safety is a properly earthed 'whole house' protector. The word 'earth' being more important than the word 'protector'. Human safety demands GFCIs.

 

[Mark R]

A typical lightning strike consists of 20,000 to 100,000 amps at 30 million volts

Lightning isn’t the only source of electrical surges. Many the Home devices that are sensitive to electrical surges also produce electrical surges. Motor driven equipment, such as garage door openers, refrigeration, and air conditioners are not the only sources of electrical surges within the home. Television,computers, microwave ovens, and modern gas ranges and furnaces that use electronic ignition can also cause line disturbances and surges.

These internally generated surges are often of small amplitude. Codes specify the minimum amount of surge protection required for electronic devices (e.g. IEC 61000-4-5), which should comfortably deal with any surge of this type.

There is a common misperception that larger surge amplitudes deposit more energy into a SPD. IEEE research shows this is not the case. Energy deposited into MOVs actually decreases as surge intensity reaches certain levels. Therefore, Joule ratings are misleading. The surge industry’s technical community avoids Joule ratings in this context.

Energy is defined as Power x Time. How are Power and Time defined and where are Watts actually going?

Agreed. Joule ratings are misleading. The important parameters are diversion current, clamping voltage and surge duration.

For most internally generated surges, the duration is unlikely to be more than about 20 us. Lightning, however, generates much longer surges - up to 500 us.

However, calculating the power dissipated in the varistor is difficult - and depends on the clamping voltage, surge current, source impedance, etc. A surge protector on the end of a long low-current cable will absorb less energy than a whole-building protector connected direct to a very low impedance supply, even in response to the same surge.

However, as surge amplitude increases (all other things being equal) energy deposited in teh varistor will always increase.

Another example, can the SPD sustain a Joule rating many times, one time, or does it define failure? At least one manufacturer uses a multiplier. For example, if an MOV is rated 1J, but can withstand 5,000 hits, the SPD is rated 1J x 5,000 = 5,000 Joules. In summary, Joule ratings are not recognized by surge suppression Standards.

They are not an important parameter in the industry. However, good manufacturers will provide joule rating graphs/tables. That specify how many surges of a particular energy, the device is likely to withstand.