Generator Plug

[bwat]

Customer has small split phase 120/240 generator with 240V L6-30R plug (there are also 120v plugs). He's asking if he can derive 120V from the L6 plug. In essence use a hot and the EGC prong to get 120. I've told them this is a bad idea and probably against code. It's similar to stealing the EGC at regular outlet for a neutral.

I don't have a wealth of generator experience, so I'm asking here to see if there are any alternatives to my thinking and/or code references. Realistically what he's asking would work, and the cable that plugged into the L6 outlet would act like service conductors where the neutral/grounded conductor is accomplishing both the neutral and EGC, but I didn't think this was permissible. Perhaps they (neutral and egc) could then be split at small panel next to the generator.

Generator states the neutral is bonded to the frame.

I'm not actually sure why they are wanting to do this in the first place, but that's a different question...

Thanks in advance

 

[zbang]

The best answer is No; there are too many problems with this in general (not the right connectors, bonded neutral, and probably others).

If you change to an L14-30, you're OK on the connection but might void any warranty or NRTL listing; OTOH it'll be a much safer setup. And mind the bonding jumpers wherever they are.

 

[infinity]

Customer has small split phase 120/240 generator with 240V L6-30R plug (there are also 120v plugs). He's asking if he can derive 120V from the L6 plug. In essence use a hot and the EGC prong to get 120. I've told them this is a bad idea and probably against code. It's similar to stealing the EGC at regular outlet for a neutral.

I don't have a wealth of generator experience, so I'm asking here to see if there are any alternatives to my thinking and/or code references. Realistically what he's asking would work, and the cable that plugged into the L6 outlet would act like service conductors where the neutral/grounded conductor is accomplishing both the neutral and EGC, but I didn't think this was permissible. Perhaps they (neutral and egc) could then be split at small panel next to the generator.

Generator states the neutral is bonded to the frame.

I'm not actually sure why they are wanting to do this in the first place, but that's a different question...

Thanks in advance

Are these actually plugs or receptacles?

 

[bwat]

Whoops. They're receptacles on the generator as you would probably expect. Sorry about the confusion.

 

[iceworm]

Customer has small split phase 120/240 generator with 240V L6-30R plug (there are also 120v plugs). He's asking if he can derive 120V from the L6 plug. ...

How old is the genset?
I ask cause I had an older diesel drive welder with an 8KW generator - probably 1980s vintage. Receptacles were as you said, two 120V, 20A duplex, each with a single pole CB and a 30A 3pole 240V with it's own 2 pole CB. I'm thinking, use the 120V as the neutral and have a 120/240 1phase I can use for the house power - I'll need to install a new 4W receptacle. Nope. The two windings are not electrically connected. Yeah - I don't believe that - got to be a broken wire. Tear the gen apart - trace the connections. Two separate windings. I don't recall now exactly what the grounding/bonding was on the 240V winding. Color me surprised.

Recommend:
Check if the 240V supply does have a connection to a neutral. If not, end of problem.
Open up the gen and chase the connections
Yes, as said, a 4W receptacle is a really good idea. As said, it is important to have separate neutral and ground. If the application is a house standby power, either separate the gen neutral and ground, (remove the N-G bond). Or get a 3W transfer switch
Depending on the age I wouldn't worry about the warranty
The change, if possible, can be done in a safe manner regardless of the listing. The ahj rep may well burst into flame when walking by.

... I don't have a wealth of generator experience, ...

You want to get this right.

 

[bwat]

Thanks for the feedback.

What I’m hearing is that this isn’t typical, most likely against a code rule or listing, but could probably be done in a somewhat safe manner as long as you understand the consequences and what you’re doing.

If this was something I was doing at my own house temporarily, I’d be more inclined to let it happen, but professionally I’m not willing to associate my name with it.

I was concerned that I was being overly conservative and that it was something that was done all the time and is acceptable. Thanks again.

 

[RD35]

I agree with your logic on this. I, too, would not put my name to this if it were me. If I was the owner of the generator and this was for, say, my own house, then sure it might be just fine to swap out the L6-30 for an L14-30. Add a neurtral wire to the receptacle assembly and disconnect the bond in the generator head.....or leave the ground and neutral bonded in the genny and install a 3-pole transfer switch so I could switch the neutral. But for a client...no way. The reconfigured generator would not be set up as factory original and that could open up all sorts of liability...IMHO.