Suppose someone has a 240V 50A plug at a rental house. It is wired to a 10-50 receptical. My understanding is that this is a deprecated standard, and my guess is that it is 6-50 wiring that was put into a 10-50 receptical.
Suppose they want to change the receptical to 6-50.
There are three wires which I will call (G)reen, (R)ed, and (B)lack. The heavy duty wire is in a metal sheath that is earthed (E)
Using a multimeter I detect: E-G: 0 E-R: ~120V E-B: ~120V G-R: ~120V G-B: ~120V R-B: ~240V
My read of this is that I can simply change the receptical to 6-50.
- Is there any specific risk to this? It's a relatively modern house.
- Are there any other tests that I can perform to determine whether this is 10-50 wiring or 6-50 wiring?
- Does this matter? The difference seems rather subtle.
Aside: It's not particularly relevant, but the wire I referred to as red was actually white. It's clearly live, so this is the "typical" I've-only-got-three-wires-and-don't-want-to-cap-a-white-wire-so-I-declare-white-equals-red. I have put black tape on it to make this clear.
I haven't opened the distribution box to look at the wiring, but am hoping that the multimeter can give me enough information.
As requested, here is a photo of the junction box internals, showing the white wire (with a bit of black tape on it), black wire (these are both hot and 180 degrees out of phase), and green wire (it is 0V from the earth and electrically connected to it presumably at the distribution board).
Further thought: According to this discussion board which agrees with my other reading, 10-50 is hot-hot-neutral and 6-50 is hot-hot-earth. Since my green wire is in continuity with the box, my wires are hot-hot-earth.