what wire is this?

[threeputts]

Electrician installed a 14-50 in the garage last year that I have been using to charge our MY via the UMC. With a M3 pickup scheduled for this week I thought a HPWC might be worthwhile so I went to check the wiring to see if it could support a 60A breaker but now I’m concerned it’s 8/3 romex from a 50A breaker. Is there an easy way to tell?

 

[miimura]

wow. that is the worst dot matrix printing I've ever seen. Before reading your text, I guessed it was NM-B 6-3, but I can see how it could be 8-3. If you can see the ends, you may be able to figure it out by looking at the bare conductors. However, you would have to use a caliper to measure the exact wire diameter and count the strands if it's stranded wire.
Good luck.

 

[Rocky_H]

wow. that is the worst dot matrix printing I've ever seen.

Yeah, that is some really nasty, sketchy printing. Like...they printed clearly, but you can't use dots that large on a letter that small. I would think that looks like an S, but I know that's not it, so it's between a 6 or an 8. I think that does look like it says 8-3, but that seems unlikely. I would also say to try to measure it somehow. Or if you can hacksaw a tiny piece off of it, you could take it to a hardware store to see exactly what wire gauge it matches up to.

 

[RayK]

Or if you can hacksaw a tiny piece off of it, you could take it to a hardware store to see exactly what wire gauge it matches up to.

Ah, make sure that you switch the breaker off before doing that!

My take on the inadequate dot matrix printing is that it reads "8-3".

 

[Sophias_dad]

If you trust the builder/electrician, that is 6/3, since nmb 8/3 isn't allowed to be used with a 50 amp breaker(assuming a 40 amp is available for that panel). That said, I think that's an 8, since it would be easy to remove a dot and make it a clear 6

 

[gfunkdave]

It looks like 8-3 to my eyes.

I'd just replace the breaker with a 40A one and call it a day. 40A breaker is still plenty fast unless you routinely need to pull into the garage with a nearly flat battery and then expect to drive 300 miles five hours later without a Supercharger.

 

[threeputts]

It looks like 8-3 to my eyes.

I'd just replace the breaker with a 40A one and call it a day. 40A breaker is still plenty fast unless you routinely need to pull into the garage with a nearly flat battery and then expect to drive 300 miles five hours later without a Supercharger.

I agree that would be simple but I paid for a 14-50 outlet. I emailed the electrician this picture and no reply. I'll give him a couple days then start calling.
In the meantime the UMC is plugged into it and that only draws 32 amps max.

 

[Sophias_dad]

that only draws 32 amps max.

That's actually why your house hasn't burned down, since the 8 gauge wire is only rated for 40 amps(32 continuous). Another 'professional' at work. I'm not sure what a consumer is supposed to do.

 

[davewill]

I think it's a "8". If it were a "6" it should have 4 dots on the middle line like the "B" does before it.

 

[threeputts]

I found a section in the garage with better printing, the wire is definitely 8-3. Question now becomes is this to code for a 14-50 outlet? It’s on a 50amp breaker. The part that runs inside a wall is in conduit but through the basement rafters and in the garage most of it is exposed.

 

[richrootes]

Regardless of all that, aren’t your cars limited to 32A?

 

[ucmndd]

. Question now becomes is this to code for a 14-50 outlet? It’s on a 50amp breaker.

Most certainly not. 8/3 nm-b is good for a max of 40 amps.

Now, if you’re using the Gen 2 UMC which draws 32 amps max, you’re not in particular danger of anything bad happening. But if someone comes along later and plugs something into that outlet that can draw a full 50 amps, that’s a big issue.

You either need to replace the 50 amp breaker with a 40 to protect the undersized wire, or redo the run with #6 conductors.

 

[RayK]

You either need to replace the 50 amp breaker with a 40 to protect the undersized wire, <snip>

And if you do that I would label the 14-50 outlet with something like "40A breaker, 32A continuous max." to warn people about the current limitation.

 

[davewill]

Most certainly not. 8/3 nm-b is good for a max of 40 amps.

Now, if you’re using the Gen 2 UMC which draws 32 amps max, you’re not in particular danger of anything bad happening. But if someone comes along later and plugs something into that outlet that can draw a full 50 amps, that’s a big issue.

You either need to replace the 50 amp breaker with a 40 to protect the undersized wire, or redo the run with #6 conductors.

Using a 40a circuit on a 14-50 is a very common install in the non-Tesla EV world. One of my outlets (happens to be a 6-50, but same idea) uses 8ga NM-B and a 40a breaker. I've charged three different EVs on it and no worries. Sure, if I had known better at the time, I might have sized the wire bigger (and I might not have considering my LEAF at the time topped out at 16a), but there has never been any real need to change anything.

 

[ucmndd]

Using a 40a circuit on a 14-50 is a very common install in the non-Tesla EV world.

Yes, very common with things like induction ranges and specifically allowed by code as there aren’t any 40 amp NEMA receptacles.

But of course you have to have a 40 amp breaker to protect the 40 amp rated conductors, which OP does not. That’s a problem.

 

[davewill]

Yes, very common with things like induction ranges and specifically allowed by code as there aren’t any 40 amp NEMA receptacles.

But of course you have to have a 40 amp breaker to protect the 40 amp rated conductors, which OP does not. That’s a problem.

I thought that had been made crystal clear by this point, and saw no point in beating that hayburner any more.

 

[ucmndd]

I thought that had been made crystal clear by this point, and saw no point in beating that hayburner any more.

Then I guess I didn’t understand why you were responding to my post with the info you provided. All good.