Did a little Googling. First: ROMEX is a brand name. It's
type, for the purposes of current carrying, is NM-B, where, "NM" means non-metallic sheathing.
Fast answer: No, you're not OK. See this link:
Cerrowire Resources - Ampacity Charts
NM-B has a current carrying limit of 55A. That's the
circuit rating. If you have a 60A breaker, you're supposed to be using wire that can handle 60A or better. Oops.
What's going on? I'll make it short and simple.
- The wire you want is made out of copper.
- Copper has resistance, usually expressed as ohms per foot, or maybe ohms per meter.
- Power dissipated in a wire, per unit length, goes as Current*Current*Resistance/Length, and that gives you Watts per foot, or maybe Watts per meter.
- So, there's heat in that there wire. It has to be dissipated to the environment somehow, or it's going to heat up until it turns white-hot.
- The heat has to go through the plastic insulation. Futher, if the cable is buried in a wall somewhere, the heat has to get through the wall materials into the open air. You get the idea. The manufacturer of said wire has the temperature that the wire has to run in, what the material is made out of, and builds it to that spec.
- The electrician in your case definitely used the wrong wire. Should have used, say, ROMEX 4/3, which, because the wire is thicker, it's got less resistance, generates less heat. Or used some other wire in that table linked above that's good, with 6GA wire, for 65A or 70A.
- Note: If an electrical inspector sees this, it won't pass.
- In this list, final, but Really Important Note: Violate the NEC and what happens is that the insulation gets degraded. Maybe not on the first shot, or the second; but, eventually, the insulation goes bye-bye and You Get A Short (if you're lucky) and the breaker pops or a partial short, in which case the breaker doesn't pop but the house burns down. I'm not joking.
Next short list: the NEC circuit limits are, vaguely, for loads that don't last very long. Constant heavy loads result in the circuit being derated 20%. Which is why you need a 60A circuit to carry a 48A (80% of 60A) load.
So, you've got the wrong wire installed. It's only good for 55A. 80% of 55A = 44A.
But this is an installation for the long term. My opinion: Drag the electrician back, threaten him/her with the local building inspector, and make him/her fix it by using the correct gauge and/or type of wire.
Minor comment: Right now, in Central New Jersey, there's a local electrician advertising on the radio for wiring up houses for electric charging. His particular shtick is that he's got Factory Trained Technicians on staff that'll will do it right. But he makes the point that, even if you don't use his company's services, that one should make sure that the installer is
trained on this stuff. Man has a point. It's advertising, but he still has a point.
www.zillerelectric.com
