Is 14 AWG needed here or is 18 AWG fine?


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Old 09-27-22, 09:58 PM
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Question Is 14 AWG needed here or is 18 AWG fine?

I'm working on another one of Peter's mad scientist type projects and I bought a digital multi-function meter

It uses a CT (Current Transformer) and it has those cheap screw type terminal blocks and it is extremely difficult to get my 14 AWG wires to stay put in them!

I'm thinking 18 AWG is fine as that is just powering the meter my main input and output cords are both 14 AWG/3C the CT has what looks to be 22 AWG but I think it does not really carry any current correct?

So is my assumption correct that I can get away with 18 AWG for powering the meter?

I know this is not going to pass UL standards but I don't want to do anything unsafe (not like I really care about the NEC or NFPA's rules but I do care about blatant safety hazards)

Thank You
- Peter the mad scientist LoL!
 
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Old 09-27-22, 10:17 PM
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The CT is one thing but powering the unit with #18 ?
The CT is probably 50:1 or even 100:1 which means one or two amps.

If you're going to put that meter into a case with a #14 power cord in and out.....
then I'd say... yes... #18 is fine inside the case. Wouldn't hurt to fuse it at an amp or two.
 
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Old 09-27-22, 10:44 PM
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#18 is fine inside the case. Wouldn't hurt to fuse it at an amp or two.
The 14 AWG is in and out with the out receptacle's black hot wire going through the CT the 18 AWG in question is only going to power the actual meter which probably does not even draw 100 Watts.

Is a 3A thermal circuit breaker OK it is rated at 250VAC/48VDC this was pilfered from a dead APC UPS many many years ago and I think this is a good use for it (finally)?

PS I like you name LoL! My name is Peter but Pete for short even though I hate being called Pete
 
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Old 09-28-22, 10:34 PM
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Pete here.

I prefer a fuse but that circuit breaker should be ok. (I don't trust off shore electronics.)
 
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Old 09-29-22, 08:37 AM
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Any conductors connected to the mains should be the same size as the main. Little to no documentation and no listings shown and both would make me leery. Smaller conductors are acceptable if part of a listed assembly, which this obviously isn't.
 
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Old 09-29-22, 09:41 AM
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I agree but that isn't possible with a device like that. It will not accept large wiring.
That's the reason for additional protection.
 
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Old 09-30-22, 05:27 PM
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Conductors connected to the mains ...

There is the "tap rule" that allows thinner conductors not exceeding a certain length to connect to the feed at a junction box. Typically the wires going to the lamp sockets in a light fixture qualify. The distance from the light fixture to a wall switch almost always does not qualify.

Or is it that being in (when they are in) an Underwiters Labs listed assembly that allows the light fixture leads to qualify?

I don't have the size and length table from the NEC handy but chandelier wires threaded through the chain are also something like 18 gauge tapped into 15 or even 20 amp circuits up in the ceiling. (I think CEC limits lighting circuits to 15 amps).
 
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Old 10-13-22, 03:34 PM
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Well I could not find my 3A breaker and I'm too cheap to buy a fuse holder so I just wired it as-is with about 4" of 18AWG TEW wire that I got from a dead smoke detector so I assume this wire is OK as it is from a life safety device?


Inside of box showing the wiring



Side view and view of of the inlet and the 14AWG/3C pigtail outlet!


View of device powered on with nothing plugged into it, showing it works




Some time down the line (When I can get more "consumables" for my Black & Decker RTX) I might make a revision 2 as I found out (VIA Amazon reviews) that the cutout is slightly larger then the GFCI device cutout so I might get a 1900 box and a metal cover and grind it down so it can snap in to the hole as this box is a bit big plus version 2 can use a regular receptacle in a 2 gang box thus providing me with 2 receptacles!
 
 

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