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Generators & Motors General Discussion Antique Generators, Light Plants and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Motors General Discussion

Plug Wiring Question


Okay, I know this is dumb, but better safe than sorry. One of my generators has two 20 amp, 115...

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  #1  
Old 02-07-2005, 10:02 PM
Zira Zira is offline
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Default Plug Wiring Question

Okay, I know this is dumb, but better safe than sorry.

One of my generators has two 20 amp, 115 volt 3-prong twist-lock outlets. The mating plugs have the 3 connections labled G, X, & Y. G is obviously ground by shape & color (green). My question is, which does the black wire go to & which does the white wire go to (or, which is hot & which is neutral)? I am used to the plugs where the terminals are color coded (green, silver, and brass/gold). BTW, these are Hubbell plugs, if that matters.

Thanks for keeping me from electricuting myself or frying all my electrical stuff.

David
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Old 02-07-2005, 10:53 PM
Jim Tremble Jim Tremble is offline
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Default Re: Plug Wiring Question

David

White goes to the Silver and Black goes to the Gold or Brass terminal. Green is ground.

Jim
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Old 02-07-2005, 11:49 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Plug Wiring Question

Right. But this plug doesn't have silver and gold screws.

Is this a L5-20P plug? According to the picture in my Graingers catalog, the neutral is the prong nearest the bent tang end of the ground prong.

I suspect you may not have a L5-20P. If it's labeled X, Y, and G, it could very well be a 240V plug. (like maybe a L6-20P?) All the 120V plugs I see here are shown with a W - indicating white, or neutral.
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Old 02-08-2005, 08:07 AM
Mark Abby Mark Abby is offline
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Default Re: Plug Wiring Question

here is a web site that may help you identify what you have. (you need adobe reader..it's a pdf file)

http://www.hubbell-canada.com/wiring...t/pdf/h/h3.pdf
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Old 02-08-2005, 05:43 PM
Zira Zira is offline
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Default Re: Plug Wiring Question

Thanks for that link, it is clearer than the picture in the McMaster-Carr catalog. It is an L9-20. Does that help?
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Old 02-08-2005, 07:29 PM
Jim Rankin Jim Rankin is offline
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Default Re: Plug Wiring Question

since you are certain which is the ground, plug only the body of the plug into the outlet and start the generator. Then check with a voltmeter between the three plug connecting screws and the frame of the generator. The ground should show no reading, the neutral might show some small voltage, probably not, and the hot should show 115 to the frame, the ground and the neutral. This way you can be sure you are wiring the plug correctly for your generator.

Jim
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Old 02-08-2005, 08:24 PM
Mark Abby Mark Abby is offline
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Default Re: Plug Wiring Question

why not open up the panel box on the generator and see which is wired to where?
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Old 02-08-2005, 11:15 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Plug Wiring Question

Is this a home-built set? It's odd that there's a L9-20 outlet - that's a 600V connector. It does not have a designated neutral prong. It has a ground and two hots.

Let us know the results of the test that Jim R. suggested.

Also, there may not be a neutral. Some gensets don't bond either output line to ground, so neutral is whichever one you bond to ground.

Is there also a regular 120V outlet on the set? That'll tell us which line is neutral...
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Old 02-09-2005, 09:23 PM
Zira Zira is offline
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Default Re: Plug Wiring Question - some answers

Thanks for all the help. Here are the answers to some questions people asked, and some things I found:
- It is not a homebuilt set, and these are the original outlets. I bought 2 of these from a guy who bought 4 at an auction from a county auction, and they were all the same.
- I said the outlet was a L9-20, that is not correct. It is the same pattern as an L9-20, but a different diameter. I went to the Hubbell web site, and I could not find it there at all. It is still available (at least within the last few years), as I found another male plug of this pattern on a fairly new piece of equipment headed to the scrap yard from a local plant that was closing.
- Instead of trying the test Jim Rankin suggested, I wired a pigtail to a normal 15-amp outlet & used one of those $4 testers with the LED's. This allowed me to sort it out.
- At least on my genset, X is the black (hot) wire, and Y is the white (neutral) wire. This is consistent on both outlets, on both generators.
- Interestingly, the plug I found this week was wire the other way (Y was hot).

I would still like to know what the correct name for these plugs/outlets is (like L5-20). Maybe it is not a NEMA-standard configuration?

David
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Old 09-24-2009, 04:07 PM
Short43158 Short43158 is offline
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Default Re: Plug Wiring Question

I'm sure it has a NEMA number can you post a pic for me I am very visual telling me it looks like a L9-20 really don't work for me.
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Old 09-24-2009, 04:20 PM
Wayne 440 Wayne 440 is offline
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Default Re: Plug Wiring Question - some answers

Quote:
Originally Posted by Zira View Post
...I would still like to know what the correct name for these plugs/outlets is (like L5-20). Maybe it is not a NEMA-standard configuration?...
Not all locking plugs have a NEMA nomenclature. This http://www.lexproducts.com/cs/indust...oductLineId=23 may be what you have.
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Old 09-24-2009, 04:38 PM
Short43158 Short43158 is offline
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Default Re: Plug Wiring Question

I take it all back maybe your plug is a non NEMA look at the chart in the lower left (you may need to zoom I did)
http://www.passandseymour.com/litera...mat_101107.pdf
There is a plug and receptical set that looks like L9-20. Really it looks more like L8-20, but I think it might be your plug.
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Old 09-24-2009, 09:58 PM
Jim Rankin Jim Rankin is offline
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Default Re: Plug Wiring Question

I wouldn't waste too much effort on this one, it's over 4 years old!
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