Ground wire routing

[dkarpov]

At my parents' house, they have a 240V 30A circuit going to a regular interior 2-prong outlet. I have no idea what that would have ever been used for. I pulled off the cover plate and the two hot wires are connected to the plug, and there is a very thin ground wire in the box not connected to anything.

If I were to convert this to a 6-30 outlet, is that thin ground wire enough? If not, can I run a separate ground wire to the ground rod instead of back to the breaker box?

 

[Lloyd]

Grounds have to go back to the breaker box by code. I'm not sure what you have with a 2 pronged 240 V circuit. All 240 V plugs have at least 3 and a ground to the plug.

 

[AP997S]

My advice for you and/or your parents is to call in a qualified electrician to sort it out. You could be dealing with a catastrophe by not correcting this issue. Violating national or local electric codes can cause major consequences.

 

[dkarpov]

Well, in its current state, my parents are well aware of the 240V nature of this outlet and haven't been using it. I was just wondering if I could leverage it by bringing it up to some sort of code.

 

[Rocky_H]

Huh--this is an interesting one.

I pulled off the cover plate and the two hot wires are connected to the plug, and there is a very thin ground wire in the box not connected to anything.

If I were to convert this to a 6-30 outlet, is that thin ground wire enough?

Well, that depends on what gauge a "very thin wire" is. There is a specific table of how thick the ground wire needs to be for how many amps the circuit is rated for. For a 30A circuit, the ground wire needs to be 10 gauge.
Equipment Grounding Conductor Table 250-95

Need to split this up:

Grounds have to go back to the breaker box by code.

I'm not quite sure about that one. I know neutral lines do have to go all the way back to the panel. I thought grounds might be able to tie to grounds in other places. Need someone with a better answer on that one.

I'm not sure what you have with a 2 pronged 240 V circuit. All 240 V plugs have at least 3 and a ground to the plug.

Well no, that's not true. All of the 6-XX series of outlets are 240V with only three wires: Hot1, Hot2, and ground. You are thinking of outlets that need to be dual voltage 120V/240V, like the 14-XX. Those also need the neutral wire, so they can have that 120V between one of the hot lines and the neutral. But a 6-50 or 6-30 is just three wires. In this case, the ground wire is hanging and not hooked up, so it's not currently installed properly, but that can probably be fixed and brought up to code with what is there.

If not, can I run a separate ground wire to the ground rod instead of back to the breaker box?

This can probably be fixed pretty easily. Since the ground wire is in the box already, I would think it does go somewhere useful--maybe comes out right there in your panel where the other two wires go anyway. If you can identify it there, then that would help. So maybe the other end is already tied to a valid ground point, and it may just need to be attached to the outlet. That would be a pretty simple fix then.

 

[Lloyd]

Huh--this is an interesting one.



Well no, that's not true. All of the 6-XX series of outlets are 240V with only three wires: Hot1, Hot2, and ground. pretty simple fix then.

Last time I checked three is more than two!

 

[dkarpov]

Whatever this outlet was intended to be, it is definitely not up to any sort of code. It is a literal two prong 115V outlet with two hot 120V wires hooked up to it. The ground wire loose in the box is at most a 14 gauge wire. Given the gauge of the two hot wires, I am not comfortable using that ground wire as it is. My parents have a crawlspace and an attic space, so I can probably run a wire back to the box if I have to. Going straight to the grounding rod would be easier, though, thus my question.

In my research, most of what I read was in regard to grounding outlets that also had a neutral. Code requires that, in those cases, neutral and ground are bonded at the box in order to trip the breaker in a ground fault situation. It is less clear if there isn't a neutral involved.

To be safe, I'll probably just entirely disconnect the wires to that outlet and run a new set from those fuses to my location. Then I can also run a neutral and install a 14-30 outlet.

Thank you all for your input and advice.

 

[Rocky_H]

All 240 V plugs have at least 3 and a ground

Last time I checked three is more than two!

You said "3 AND a ground". That is four wires. So no, 240V outlets don't all have to have four wires.

It is a literal two prong 115V outlet with two hot 120V wires hooked up to it.

Oh, I don't think you had mentioned that part. It's actually a 5-15 or 5-20 outlet, like a 120V type? Yeah, that is scary if they had that wrong outlet type hooked up to two hot lines at 240V. That could pop an appliance if something got plugged into it.

To be safe, I'll probably just entirely disconnect the wires to that outlet and run a new set from those fuses to my location. Then I can also run a neutral and install a 14-30 outlet.

Good call. There is a whole lot of weirdness about this one that would make it hard to trust using what is there.

 

[paulk]

You should NOT use a separate ground, it’s against code to have more than one ground. In case of a fault you can get a ground-ground electric flow which starts fires (theoretically).
As for that strange outlet, it sounds like it’s breaker should be disconnected. A 30 amp outlet should have at least 10 gauge wire with a ground, preferably a neutral wire as well. It’s possible you can re-breaker it to a regular 15 amp/120 volt outlet with existing wiring.