Electrical People - Wire Gauge....what size?

[bob4432]

running some security cameras and have all the equipment. the cameras are 24VAC and i have read that there is no problem running that through cat5/5e and it is done all the time. the transformer for this setup is a 24VAC 10VA unit per 2 camera. i put a kill-a-watt on it and it shows a draw from the wall of 4W and 5VA for the 2 combined cameras, so each one is pulling 2W and 2.5VA (if that is how AC is done - that is my problem, i can't remember how AC stuff is done, just DC). is solid cat5/5e ok w/ this amount of power? it seems like such a small little wire, but i know it is pulling such a small amount of power, but if i catch the house on fire, well, i think the wife will kick me in the nuts.

i looked up the cable and it is 24AWG solid copper - i took it out of the sheath and is cool to the touch and the "run" is like 4' if that.

fwiw, if anybody is pondering on using the cat5/5e/6 for video, the quality is the same on my dvr as it is w/ coax - nice to be able to run 2-4 cameras w/ just 1 wire for the video feed. personally just using some b/w "high resolution" board cameras but have larger box cameras that look just as good too. i think they are over 500 vertical lines and compared to my color cameras that are 380 lines, these are definitely crisper.

tia,
bob

 

[Jeff7]

*cough*
Google

Oh, sorry.
Anyway, link,

Looks like 0.577A would be the max you'd want to go for continuous power flow.



*No responsibility if your house burns down and kills people, and can I have your car if that does happen?*

 

[bob4432]

Originally posted by: Jeff7
*cough*
Google

Oh, sorry.
Anyway, link,

Looks like 0.577A would be the max you'd want to go for continuous power flow.



*No responsibility if your house burns down and kills people, and can I have your car if that does happen?*

AC always messes me up....don't know - are the computations for A the same whether AC or DC? i do the math and say 24V and .2A = 4.8W, so that would only be ~.1A if the kill-a-watt shows a total draw for 2 cameras of 4W.

 

[iGas]

According to this link you are allowed max of 2.1A in conduit, or 3.5A free-air (not in conduit), however you must de-rate it pending electrical code & manufacturer requirement (which ever is more restrictive, at the very least is 80% capacity).

3.5A * 80% = 2.8A max capacity.

 

[Jeff7]

Everything has a power factor in it with AC, and I don't know exactly how that works. I think a perfectly resistive load has a PF of 1.0, which is ideal. Most things have a PF lower than that, though some devices, mainly from manufacturers who care about efficiency and such, have PF correction circuitry which brings it closer to 1.

I don't remember which is higher though, VA or watts, but if you've got a Kill-A-Watt, just switch it to the Amps setting, and that should show you the actual current draw.

 

[bob4432]

kill-a-watt shows PF @ .92-.94, W=4, A=.04, VA=5, AC=119.7

VA mess me up too

 

[iGas]

Originally posted by: Jeff7
Everything has a power factor in it with AC, and I don't know exactly how that works. I think a perfectly resistive load has a PF of 1.0, which is ideal. Most things have a PF lower than that, though some devices, mainly from manufacturers who care about efficiency and such, have PF correction circuitry which brings it closer to 1.

I don't remember which is higher though, VA or watts, but if you've got a Kill-A-Watt, just switch it to the Amps setting, and that should show you the actual current draw.

I have seen 80%, 75%, and the most common 60% derate (PF).

I would go for 0.8 PF on non critical application short run at less than 1m (3'), and for critical application I would stick with standard 0.6 PF.

3.5A * 0.6 = 2.1A max

 

[bob4432]

off topic - man, need some infra-red light out front....motion sensor or something

 

[BigJ]

If you want this to be safe and your insurance company to back you in case of an event, I suggest you contact a Licensed Electrician in your area that deals with LV (low voltage) installations. Depending on the area, LV work is all over the place in terms of licensing and installation. You may need to pull permits and/or get inspections in your area for such work.

At the very least, get a copy of whatever edition NEC your area is using and get a version of Mike Holt's LV Handbook.

 

[Colt45]

I wouldn't go with anything less than 4/0 for that.


cat5 is fine.

 

[bob4432]

Originally posted by: BigJ
If you want this to be safe and your insurance company to back you in case of an event, I suggest you contact a Licensed Electrician in your area that deals with LV (low voltage) installations. Depending on the area, LV work is all over the place in terms of licensing and installation. You may need to pull permits and/or get inspections in your area for such work.

At the very least, get a copy of whatever edition NEC your area is using and get a version of Mike Holt's LV Handbook.

will look into that. i am assuming if there was an issue, the actual wires would be warm correct? they are cool to the touch. i have used the cameras before but the wire i used in the past had a bit more insulation and was probably 20AWG or so, 24AWG is just sooo small, but i guess they do power POE devices w/ it and what i am doing is done in a lot of professional security setups, just 24AWG....tiny stuff. have never used that stuff for anything other than network cable.

 

[BigJ]

Originally posted by: Colt45
I wouldn't go with anything less than 4/0 for that.


cat5 is fine.

Pssh. I stick by 750kcmil at least.

 

[iGas]

Google is your friend: -- 12 VDC & 24 VAC gauge/length table.

PS. I have done a few low voltage control wirings for HVAC & geothermal systems, and 20 gauge is standard, and on some longer run we use 18 gauge.

 

[BigJ]

Originally posted by: bob4432

Originally posted by: BigJ
If you want this to be safe and your insurance company to back you in case of an event, I suggest you contact a Licensed Electrician in your area that deals with LV (low voltage) installations. Depending on the area, LV work is all over the place in terms of licensing and installation. You may need to pull permits and/or get inspections in your area for such work.

At the very least, get a copy of whatever edition NEC your area is using and get a version of Mike Holt's LV Handbook.

will look into that. i am assuming if there was an issue, the actual wires would be warm correct? they are cool to the touch. i have used the cameras before but the wire i used in the past had a bit more insulation and was probably 20AWG or so, 24AWG is just sooo small, but i guess they do power POE devices w/ it and what i am doing is done in a lot of professional security setups, just 24AWG....tiny stuff. have never used that stuff for anything other than network cable.

I haven't done any type of low voltage work since graduating and changing career paths, but with electrical installations, proper sizing of current carrying conductors is only one worry amongst many. Improper installation will burn you just as often if not more than improper sizing of the conductors.

This is where the NEC and local codes will come in handy the most.

 

[edro]

My chart (NEC 310.16) shows 24AWG is good for 2A.
10VA/24VAC = .416A (Power factor and voltage drop are so low I left them out)

Even if it is derated because it is twisted pair in a jacket, and even if it is in conduit, you are still well within the limits of the wire.

As for NEC, ELV (Extra Low Voltage) circuits don't have nearly the regulation that "Low Voltage" (30V-600V) has.
The only major stipulation is that it must be segregated from Low Voltage by a barrier.
Do not run the wire directly next to your house wiring.

If the Transformers are Class 2 (which they have to be to be used in a home), they are internally protected so they will not exceed their rated output.
That limits their fire-creating properties greatly.

I think you're ok using Cat5 for this application.

 

[Analog]

Originally posted by: bob4432
running some security cameras and have all the equipment. the cameras are 24VAC and i have read that there is no problem running that through cat5/5e and it is done all the time. the transformer for this setup is a 24VAC 10VA unit per 2 camera. i put a kill-a-watt on it and it shows a draw from the wall of 4W and 5VA for the 2 combined cameras, so each one is pulling 2W and 2.5VA (if that is how AC is done - that is my problem, i can't remember how AC stuff is done, just DC). is solid cat5/5e ok w/ this amount of power? it seems like such a small little wire, but i know it is pulling such a small amount of power, but if i catch the house on fire, well, i think the wife will kick me in the nuts.

i looked up the cable and it is 24AWG solid copper - i took it out of the sheath and is cool to the touch and the "run" is like 4' if that.

fwiw, if anybody is pondering on using the cat5/5e/6 for video, the quality is the same on my dvr as it is w/ coax - nice to be able to run 2-4 cameras w/ just 1 wire for the video feed. personally just using some b/w "high resolution" board cameras but have larger box cameras that look just as good too. i think they are over 500 vertical lines and compared to my color cameras that are 380 lines, these are definitely crisper.

tia,
bob

CAT5 should be fine. If you want to be extra safe, I would recommend some type of current interruption device after the transformer. An in-line fuse or circuit breaker set above your draw current, just in case the wire gets shorted or some other fault comes into play. That would pretty much prevent any overheating of the wires downstream.

 

[skyking]

the video converter uses one pair. I always use two pair to run the power out, and I still have one spare pair.

 

[Rubycon]

Why not use power over ethernet?

 

[skyking]

Originally posted by: Rubycon
Why not use power over ethernet?

analog cameras

 

[bob4432]

well, the condo didn't burn down and the wires are still cool to the touch. thanks for those that looked the info up appreciate it, and all the comments