ECN Forum Forums General Topics of the Trade General Discussion Area Straight 240 volt generator receptacle

A customer has a nice DeVilbiss GT5000 generator that he would like to use as a back-up source.
The problem I see is that it has 2 duplex receptacles. One 120 volt and one straight 240 volt(2-wire,3-pole, grounding).
Mine has a 240/120 3-wire 4-pole Twist-lock receptacle to feed a transfer panel or switch.
I don't believe his is designed as a backup source, due to the straight 240 volt configuration.
What do you think?

If there’s room, replace the 240V receptacle with: http://www.hubbellcatalog.com/wiring/section-b-datasheet.asp?PN=HBL2716

Like Bjarney is mentioning.(didn't view the linked item, but figure it's a supplimental connection with - possibly OCPD - which will allow a 3 wire + ground connection).

If the 240 VAC receptacle's EGC tab is connected to the winding's center tap directly (not just to the frame), then an EGC could be bonded to the frame and the receptacle could be swapped out for a 3 wire + ground receptacle.

For the absolute simplest (and "cheap-o") method, just plug in needed loads during power loss! Unplug them from normal power outlets, and plug them into the Genny.

This is a non-efficient, yet effective method; but many extension cords are required!


Just added this to give the alternate option, not to be a jerk!

Scott35

Thanks, Guys.
I was thinking along those lines, but had a concern about "field modification" of a listed unit.

If the field modification involves using a listed/recognized component specifically intended for such a use (in this case panel mounting a socket), does that void the original UL Certificate on the equipment being modified?

I can understand the concern if the mod involved pigtailing a standard in-wall twist-lock and drilling and punching holes in the panel in order to mount it.

Wouldn't this be in the same category as replacing a standard two-pin plug on a piece of equipment (like a life-support machine) with a twistlock (of same volt & amp config) so that it doesn't get yanked by accident out of the wall socket?

Sven, modifying the portable genset with the suggested flanged receptacle would void any listing the set had—without question.

At www.nooutage.com/pkg003.htm note their comments about substitution of a NEMA 14-20R for the 6-20R. In part it says,

“NOTE: Depending on availability, we may substitute DeVilbiss #GT5250. This unit is identical to the above except it has slightly higher ratings of 5250/6500 watts and includes a NEMA L1420R twist lock receptacle in place of the NEMA 6-20R. The twist lock receptacle allows use of a standard cord set without the pigtail…”

The last generator hook up I had done; I set everything up - outlet outside, Gen Tran transfer switch in the house. Everything was going great, and I went to start up the customers gen. and there is no voltage on any of his outlets on the gen. I checked this out before I hooked up the cord to the house. I tried to tell the owner that his Gen. is NG. He couldn't believe it. It was his unit. Just wanted to pass it along, that it's good to check it befor you wire it into the house.
Happy Holidays
The owner now has the Gen. in the repair shop

Thanks, Bjarney.
Please read the section about the "30 amp generator cord set".
It has a 3-pole plug (6-20P) and a 4-pole Twist Lock connector(L14-20R).
You can see it by clicking on the thumbnail at the top of the page.
It states that it is a special cord for a generator with the neutral bonded to the frame.
They must tie the ground and neutral together in the plug.

My opinion only — Based on website data, 5250W / 240V = 21.9A. I would use the L14-30 wiring devices to not restrict capacity of the generator circuit. As far as the genset internal jumper—If the building neutral is bonded to ground {say, at the utility-meter/service-disconnect enclosure} and the neutral conductor in the building is unswitched, then the generator is not a separately-derived system, and the internal N-G jumper in the genset would seem to be a code violation.


Aside — Skim through this material…the mutant 6-20 cord-cap ‘3-wire to 4-wire’ L14-20/L14-30 connector-body bit is downright bizarre: http://www.nooutage.com/mod6-20p.htm http://www.nooutage.com/images/Col-fax2.gif