Wiring voltmeter to 50 amp outlet?

[brmorgan1991]

Hello all,

I have limited electrical experience, but I know a lot of the basics. I wired a 50 amp outlet to my breaker to hook an RV up to. I also got a voltmeter to measure the amount of electricity usage the RV is consuming. I know for sure the outlet is wired correctly to the breaker.

Unfortunately, I couldn't find any specific info for how to wire the voltmeter to the outlet. My first attempt fried the voltmeter and blew the back off it, as shown in pic.

I used 16/4 wire to connect the voltmeter to the 50 amp outlet, which was clearly a mistake. In hindsight, it seems like a no brainer that was a bad idea. I connected the line, lead, ground, and neutral to the same corresponding spots on the outlet. The line, lead, ground, and neutral of the 10awg copper cable from the breaker is also connected to the corresponding spots on the outlet. i.e. there are 2 wires in each connection point: 1 from the voltmeter and 1 from the breaker. I know for sure that each wire matches up with the right connection point type, but I see now the dumb move was having 50 amps connect to a 16 gauge wire.

How would I go about wiring the voltmeter to the outlet correctly?

I can gladly post more pics if needed.

Thanks so much,
Brandon

 

[brianmoooore]

Firstly, a voltmeter doesn't measure energy consumption, but I suspect that's just an error in terminology.
I'm not familiar with the device you've used, but I'm sure the damage to it is nothing to do with the undersized wire you've used.

 

[Avo Mk8]

It's described as a "Wattmeter" in the literature.
There are two versions: a 20A one that you wire directly to the mains, and a 100A version that uses a current transformer. From the identification on your circuit board, you have the 100A version.
They are wired differently (see below).
(TBH it's not difficult to find the instructions on the interweb!)

The reason it blew up is nothing to do with the gauge of wire!
It was to do with connecting mains to terminals that are designed for a current transformer, which connect to sensitive electronic components that don't withstand mains voltage.
I'm afraid you're going to need to purchase another one .

Did it come with the current transformer (CT coil) that should slip onto the mains feed to your socket to measure the current?

 

[brmorgan1991]

Ahh yes, wattmeter is what I meant, apologies. I kept thinking it was called something else. Thank you for your response. It did indeed come with a CT coil. I did not use it however because for some reason I was thinking it was used only in the case of connecting to a battery terminal, but a terminal is a terminal, huh? What you explained makes sense to me now.
I did a bit more research and beyond the CT connection, it seems like I only need a black and white wire now to connect to the meter for power (14-2?).
Is it safe to connect these to the same terminals on the back of the outlet that the 10 awg wire from the breaker goes to? I read that connecting 2 wires to the same terminal is bad, and also not up to code. Or what would you suggest for a power supply, aside from something like a battery?
Thanks again

 

[brmorgan1991]

Ahh yes, wattmeter is what I meant, apologies. I kept thinking it was called something else. Thank you for your response. It did indeed come with a CT coil. I did not use it however because for some reason I was thinking it was used only in the case of connecting to a battery terminal, but a terminal is a terminal, huh? What you explained makes sense to me now.
I did a bit more research and beyond the CT connection, it seems like I only need a black and white wire now to connect to the meter for power (14-2?).
Is it safe to connect these to the same terminals on the back of the outlet that the 10 awg wire from the breaker goes to? I read that connecting 2 wires to the same terminal is bad, and also not up to code. Or what would you suggest for a power supply, aside from something like a battery?
Thanks again

Or maybe just splice an old extension cord to the wattmeter so I can plug it into a 110v outlet? Just brainstorming

 

[Avo Mk8]

I did a bit more research and beyond the CT connection, it seems like I only need a black and white wire now to connect to the meter for power (14-2?).

The wattmeter doesn't require much power itself, and it won't be carrying the load current, but it does need to be on the same source of power as your load (eg on the same outlet or extension) because it will use the voltage on its mains terminals (along with the CT input, and possibly other waveform characteristics) to calculate the wattage used by your load.

Is it safe to connect these to the same terminals on the back of the outlet that the 10 awg wire from the breaker goes to? I read that connecting 2 wires to the same terminal is bad, and also not up to code. Or what would you suggest for a power supply, aside from something like a battery?

I would suggest connecting up your 50A socket directly to the breaker as you originally intended.
Then possibly "piggy back" the wattmeter from the 50A socket if that's allowed.
If doing something like that myself I'd put a low amperage fuse in the live to the wattmeter.
Otherwise, as you brainstormed, plug the wattmeter in using an extension cord, but preferably on the same mains breaker as the load.
Good luck!

 

[brmorgan1991]

That makes sense now why it needs to be on the same power source as the load. I will see about "piggybacking" to the 50amp outlet, but otherwise, I'll just make sure it's on the same mains breaker. Thanks so much again for your help!