Calling Electricians - adding a 20-amp circuit in garage

[MichaelD]

Thank you very much everyone for your detailed responses.

Modelworks: That was the most awesome post, ever. Appreciate you getting into the details of the code so that I do it right the first time.

I've learned quite a bit from all the great replies. Thanks again!

Mike

 

[Modelworks]

Sounds a bit strange to me here, running 30A through a 15A outlet. I need to check my NECA book on that. Typically the rule is that all devices in the circuit have to support the full load of the breaker. IE a 30A breaker = 30amp switch, 30amp outlets etc because there is the potential that a 15amp switch loading at say 24amps could well... catch on fire and not pop the breaker.

It is one of the changes in the 2011 release supposedly being allowed due to the new code requirements for all ARC fault breakers .

 

[MichaelD]

I understand having a 20-amp breaker and a bunch of 15-amp outlets on that breaker. Breaker sized for possible max loading of all outlets. But the 20 amp breaker that services the GFCI in the garage only services that outlet and the doorbell (strange combo). I mistakenly stated earlier that the garage outlet was ganged with others inside. It is not. So potentially, I could put a greater than 15-amp load on this receptacle and possibly burn it w/o the breaker tripping (as someone stated). Doesn't seem smart to me. But then again, I am a n00b at this.

 

[Modelworks]

I understand having a 20-amp breaker and a bunch of 15-amp outlets on that breaker. Breaker sized for possible max loading of all outlets. But the 20 amp breaker that services the GFCI in the garage only services that outlet and the doorbell (strange combo). I mistakenly stated earlier that the garage outlet was ganged with others inside. It is not. So potentially, I could put a greater than 15-amp load on this receptacle and possibly burn it w/o the breaker tripping (as someone stated). Doesn't seem smart to me. But then again, I am a n00b at this.

It is based on probable loads and not max possible loads. If it is the only outlet on that breaker then using a single 15A outlet is against code, it has to be a single 20A outlet.

A single receptacle installed on an individual branch cir-
cuit must have an ampere rating not less than that of the
branch circuit. For example, a single receptacle on a
20-ampere individual branch circuit must be rated at 20
amperes in accordance with 210.21(B)(1); however, two or
more 15-ampere single receptacles or a 15-ampere duplex
receptacle are permitted on a 20-ampere branch circuit in
accordance with 210.21(B)(3). This requirement does not
apply to specific types of cord-and-plug-connected arc
welders.

Looking at your situation where you want to run saws that use a lot of current and are likely to cause the GFCI type breakers to trip , I would use the cord and plug connected device exceptions. You can run a single 20A outlet from a single 20A breaker for a device like a table saw and not have to bother with the GFCI stuff that will likely trip. The requirement is that when you run the outlet you put the outlet at least 6ft above any area that is likely to encounter water. I would consider maybe doing what some shops do and run the outlet to the ceiling and drop the cord down to the saw from there.

 

[MichaelD]

That's a great idea, Modelworks. I'll have to see how the ceiling outlet idea will work with the garage door. Where I'm intending on putting the table saw is right under where the garage door is when open.

Oh, to the person who suggested going up to the attic and dropping the Romex down the wall, that won't work for me, unfortunately. There is a bedroom directly above the garage (2 story house), and the garage is completely sheetrocked, ceiling and walls.

 

[skyking]

That is just how I handle my visiting friend's RV. His "house" seems to trip the GFCI outlets, even though it has its own GFCI breakers. I have a pair of outlets for future garage door openers on a single 20 breaker. Michael, maybe you have the same?

 

[ShawnD1]

This is why time delay fuses were invented. (that and an apparent shortage of pennies!) If you're too young search for Edison penny trick.

Also known as the start your house on fire trick.

A 14AWG wire 100 feet from the panel will definitely have excessive voltage drop if a 20A load is presented.

It's worth noting that LOW VOLTAGE DESTROYS MOTORS. Low voltage to a light bulb or electric heater is not a big deal, but low voltage to your new table saw is very very bad. Use the shortest wires possible and don't don't try to get away with using smaller conductors. Saving a penny will cost you a dollar.

No, every electric stove I have had contact with was 220 as well. You are right about the rest.

Your house electrical sucks. When I check the black to red voltage in my house, it says 240.

Code states outlets must not be more than 6 feet from one outlet to the next , in a non living space like a garage the code doesn't apply UNLESS you make it a living space which using it for a home workshop does. The idea is that whatever your intended usage for the space you shouldn't be more than 6ft from an outlet for whatever you have to power.

I don't know about the US code, but this would be wrong by the Canadian code. Up here we're allowed to space the receptacles by 2x the length of wires commonly used in that area. Example, things in the kitchen like toasters always have 0.9m wire (3 feet). Because of that, the receptacles are spaced 6 feet apart. A toaster placed between receptacles can reach 3 feet in either direction, so 3 + 3 = 6. Things in "living space" that are not kitchen appliances typically have 6 foot cords, so the outlets in living rooms and hallways are spaced 12 feet apart.

True it will cost more to hire someone, but you are paying for the peace of mind that it is done right and your home will not burn down.

Also, having the work NOT done by a professional and NOT getting a permit to do the work means your insurance is potentially void if your screw up is what caused the fire. It falls into the same category of how your playstation has a sticker over the screws that says removing or damaging the sticker voids the warranty (meaning you opened it up and started screwing with it).


It might be worth it to run 240V to the garage and set up another power box with its own breakers. A 240Vx30A cable would give you 4x 15A circuits. You could run as many tools as you want.

 

[MichaelD]

That is just how I handle my visiting friend's RV. His "house" seems to trip the GFCI outlets, even though it has its own GFCI breakers. I have a pair of outlets for future garage door openers on a single 20 breaker. Michael, maybe you have the same?

You Sir, are a genius! There is indeed an outlet on the ceiling for the garage opener and it's on the same circuit as the GFCI outlet. The one on the celing is a normal outlet (not GFCI). It's currently full (opener and battery backup are plugged into the two outlets. But that's easily fixable.

A short, 12-gauge extension cord from the ceiling shouldn't cause any appreciable voltage drop. The plot thickens.

ShawnD1: I hear you on the warnings, and thank you for the heads-up.

 

[Modelworks]

I don't know about the US code, but this would be wrong by the Canadian code. Up here we're allowed to space the receptacles by 2x the length of wires commonly used in that area. Example, things in the kitchen like toasters always have 0.9m wire (3 feet). Because of that, the receptacles are spaced 6 feet apart. A toaster placed between receptacles can reach 3 feet in either direction, so 3 + 3 = 6. Things in "living space" that are not kitchen appliances typically have 6 foot cords, so the outlets in living rooms and hallways are spaced 12 feet apart.

NEC has a couple different requirements depending on where the outlets are located. Kitchens have their own separate code section requiring more outlets and heavier current ratings due to things like toasters being used. Common areas are 6ft from outlet to outlet. Garages only have to have 1 outlet and outdoor areas are required to have 1 outlet on the front of the home and 1 outlet on the back.

The rule is partly due to trip hazards and also because when you consider max load on something like a 15A outlet with cord losses the result is that it is preferred that nothing more than a 12A appliance should be powered from that outlet. The reason for the 12A rating is because stranded wire in extension cords and power cords has more loss than solid wire and very few power cords are going to have wire rated to actually carry the full 15A continuously. The longer the cord the greater the heating of the conductors.

 

[Modelworks]

A short, 12-gauge extension cord from the ceiling shouldn't cause any appreciable voltage drop. The plot thickens.

Get a 10 AWG or larger cord. The reason is that stranded wiring carries less current than solid wiring, so 12AWG solid is not equal to 12AWG stranded you have to go one size up to equal the same capacity and since AWG goes backward that is 10AWG

 

[MichaelD]

Get a 10 AWG or larger cord. The reason is that stranded wiring carries less current than solid wiring, so 12AWG solid is not equal to 12AWG stranded you have to go one size up to equal the same capacity and since AWG goes backward that is 10AWG

Will do. Thank you! :thumbsup:

 

[JEDI]

Get a 10 AWG or larger cord. The reason is that stranded wiring carries less current than solid wiring, so 12AWG solid is not equal to 12AWG stranded you have to go one size up to equal the same capacity and since AWG goes backward that is 10AWG

extension cords are 10ga stranded?!
geez.. always thought it was 14ga? at least at walmart

 

[imagoon]

extension cords are 10ga stranded?!
geez.. always thought it was 14ga? at least at walmart

Extension cords vary in wire size.... Check out your local hardware store I am sure they have several sizes right on the shelf.

 

[Exterous]

The best way to wire something like a garage is with metal clad and metal boxes.

:thumbsup:

Breakers are recommended to be AFCI type for all new breakers installed, they detect when two wires touch and kill the power.

Some states (Michigan) are requring AFCI

 

[bruceb]

The cost for materials is close as the GFCI breaker will be about $35 or so.
Romex or BX in 12 gauge would be about $15 ..outlet is $5 max, box and plate about $5-$8 max .. for wire, you can run EMT or BX or Romex .. my personal choice would be BX or EMT as the wire would be better protected from damage.

Wiring is extremely easy to do.
On a GFCI breaker, the Load Side Neutral and Hot wires connect at the breaker. The breaker has a wire which goes over to the Neutral Bus in the circuit panel. Ground wire goes to ground bus in circuit panel. The hardest part of this job is finding an available knockout in the panel box and getting your wire or conduit into the opening. Be sure the locknuts on the cable or pipe are properly tightened.

At the receptacle end, just connect as normal:
White to Silver screw ... Black to Brass ... Green ground wire or bare from romex to
the Green screw. You must use the correct plate for a surface mount box. The electrical section will have what you need.

Use a box like this one:

And a cover like this one:

With the larger box, you can do 2 outlets if you want. Just get a cover that mounts 2

 

[MichaelD]

Thanks, BruceB. Very helpful. The main problem is that the garage is completely sheetrocked. So, getting conduit into a knockout in the breaker box is a PITA. I haven't decided yet, but I'm either:

1. Putting a 20-amp GFCI outlet as close to the breaker box as practical; wiring will be a joke
2. Dropping a 10-gauge extension cord from the outlet on the ceiling (for the garage door opener)

1. Requires work (minimal)
2. Not real practical since wire will have to run along ceiling, down wall, etc.

Still thinking. There's time though...want to do it this weekend.

 

[JEDI]

knockout?
just run the romex out the front panel. you might need to leave the upper left panel screw loose so the wire can come out. (or dont even both with that screw. you still have 3.)















(yes, i'm joking)

 

[futuristicmonkey]

Get a 10 AWG or larger cord. The reason is that stranded wiring carries less current than solid wiring, so 12AWG solid is not equal to 12AWG stranded you have to go one size up to equal the same capacity and since AWG goes backward that is 10AWG

Don't be silly. MichaelD, the package/label for any extension cord (worth buying) will list recommended lengths and gauges for typical loads. Have a look at your tablesaw motor's nameplate and there should be mention of current/amps/amperes somewhere. Multiply that current by 120 and that will be a good approximation to use as the "power" rating when you go to determine/buy an extension cord.

Any 12 gauge cord less than ~50' will be fine. (This is a conservative guess - I know off the top of my head that a 14-gauge circuit will cause a 5% volt drop for a 15A load at 66'.)

One other thing: I do not believe that pulling romex (nmd90 for us Canadians) through conduit is supported by either code.

 

[Modelworks]

Don't be silly. MichaelD, the package/label for any extension cord (worth buying) will list recommended lengths and gauges for typical loads. Have a look at your tablesaw motor's nameplate and there should be mention of current/amps/amperes somewhere. Multiply that current by 120 and that will be a good approximation to use as the "power" rating when you go to determine/buy an extension cord.

Normally that would be true but you are not dealing with a static load when working with motors , the load is dynamic. More current when started and more current if the saw hits a tough spot in the wood. Extension cords are known for cheating on the specifications so the general rule is go one size up for the load.

Any 12 gauge cord less than ~50' will be fine.

Putting power tools on long cords is the #1 reason that motors burn out early.

One other thing: I do not believe that pulling romex (nmd90 for us Canadians) through conduit is supported by either code.

Romex is fine if it is inside conduit. The main goal in something like a garage is to protect the wiring from being damaged by activities in the garage.

 

[bruceb]

Putting Romex inside a conduit is a waste of money. If you run conduit / EMT just pull in 3 12 gauges wires. White=Neutral, Black=Hot, Green=Ground but you don't really need this if metal pipe is used with a metal box as they will ground themselves to the panel box if the proper locknuts are used at the conduit fittings. If you do this run a pigtail from the Green screw on the outlet to a screw on the meta box. As to getting conduit in behind sheetrock, that is always pesky and requires a pipe bender and a couple of offset bends, which will vary depending on wall thickness and how far back in the wall the knockout opening will be at.

 

[*kjm]

Normally that would be true but you are not dealing with a static load when working with motors , the load is dynamic. More current when started and more current if the saw hits a tough spot in the wood. Extension cords are known for cheating on the specifications so the general rule is go one size up for the load.



Putting power tools on long cords is the #1 reason that motors burn out early.

Yep if I was Mike I would wire a new outlet or go to Home Depot or a local electrical supplier and get 10/3 cable cut to the lenght he needs not a 30ft+ extension cord and put the ends on himself.

 

[Rubycon]

Putting Romex inside a conduit is a waste of money. If you run conduit / EMT just pull in 3 12 gauges wires. White=Neutral, Black=Hot, Green=Ground but you don't really need this if metal pipe is used with a metal box as they will ground themselves to the panel box if the proper locknuts are used at the conduit fittings. If you do this run a pigtail from the Green screw on the outlet to a screw on the meta box. As to getting conduit in behind sheetrock, that is always pesky and requires a pipe bender and a couple of offset bends, which will vary depending on wall thickness and how far back in the wall the knockout opening will be at.

I would imagine it would be quite hard pulling 12/2 NM-B through 1/2" EMT! :biggrin:
A trio of 12AWG THHN OTOH would be a breeze.

 

[Zebo]

CLIFFS
1. Want to add 20-amp circuit/outlets in garage
2. There is an existing 15-amp GFCI outlet but the breaker trips due to too many tools
3. Service panel is in the garage, 20 feet from where I want the outlet
4. Licensed electrical company quoted $500 for job
5. I call BS and want to do it myself

BACK STORY

I want to add a 20-amp circuit/outlets in my garage b/c there's only one existing 15-amp GFCI outlet in the garage (which is gang-wired with a few other outlets inside the house), and the associated breaker trips when I try to run the table saw and dust collector.

Not looking for fancy. I want a simple, surface mount outlet box with the standard shiny metal conduit running from it to the breaker box. Said breaker box is also located in the garage, about 20 feet from where I want the outlet.

I contacted a local licensed/bonded electric contractor and they quoted me $500 for the job. This is a new house (6 years old), BTW. This job requires about $60 in supplies; everyone knows this.

I can do the job myself, but want to do it "to code." I looked at the NEC on the www.nfpa.org website, but I can't make heads or tails of it.

I have changed outlets, installed dimmers, ceiling fans etc before, safely (appropriate gauge wire, grounding etc) but never done something like this before.

Would someone please tell me how to wire a 20-amp breaker into the box and run the wire?

I do almost everything and am a licensed general contractor but there are some things I won't mess with and electricity is one of them. Gas is the other. I don't want to break something electrically or worse have my loved ones burned alive. $500 for a licensed and bonded contractor is cheap for piece of mind IMO let alone done right and timely fashion..

Here is a pool waterfall grotto I just built. I have my own crane to lift 1200 lbs rocks and every other tool known to man andn*could* do everything else if I wanted, etc. But I hired an electrician to wire lights in grotto/pool. Hired a gas guy (plumber) to run pipe for heater. Setting me back $2800 was cheap on a over $100,000 project.

I know your house is worth more than $100,000 - $500 aint shit.



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[*kjm]

I do almost everything and am a licensed general contractor but there are some things I won't mess with and electricity is one of them. Gas is the other. I don't want to break something electrically or worse have my loved ones burned alive. $500 for a licensed and bonded contractor is cheap for piece of mind IMO let alone done right and timely fashion..

Zebo you can always find an electriction that will certify your work... just hook it up on your own and they will sign off on it for a price.... done deal.

 

[Zebo]

Zebo you can always find an electriction that will certify your work... just hook it up on your own and they will sign off on it for a price.... done deal.

I know I've been working with same electricians for 10 years. But I'm not trained and have no desire to be.