Ask Me Help Desk - How to connect a transfer switch using L14-20 to generator with L5-30 socket?

How to connect a transfer switch using L14-20 to generator with L5-30 socket?

Years ago an electrician wired in a transfer switch that has an L14-20 connector on its face, and ran a heavy cord from there to the garage where the cord also terminates in an L14-20 plug (male).

My old contractors generator had a socket connection for L14-20, but I'm looking to replace it with a generator that has an L5-30 socket.

I opened the plug and there are four AWG 10 wires: red, green, black and white. I bought a L5-30 plug but don't know how to wire it. I also searched online and can't find anyone selling a pre-made adapter cable.

Any good suggestions would be appreciated.

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Having dinner, got to go, the above may help.

Quote:

Originally Posted by Stratmando

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NEMA Plug & Receptacle Configurations Reference Chart (Straight Blade)

Having dinner, got to go, the above may help.

Thanks for the response but none of those products address the issue I described.

Is the new plug marked?

X and Y are red/black. Both blades the same size, either wire can go to either X or Y. Hots

The smallest blade would be neutral. W - White

The blade with the hook is ground. G - Green

I thought you were looking for a "premade cable", sorry if they didn't have an adapter, they do have most used cords. Plus, I would change the end, not the cable. Onnly had a second, enough time for the links, but not an explanation. Dinner was ready.

Quote:

Originally Posted by medic-dan

Is the new plug marked?

X and Y are red/black. Both blades the same size, either wire can go to either X or Y. Hots

The smallest blade would be neutral. W - White

The blade with the hook is ground. G - Green

Is that how the L14-20 is marked? I want to remove the L14-20 male plug that used o go into my old generator, and replace it with the L5-30. My concern is how to go from 4-wires and 4 prongs to 3 prongs. What do I connect to each prong and what do I do with the extra wire?

BTW my new L5-30 connector is made be Eagle and there are no x/y markings on the terminals.

Quote:

Originally Posted by Stratmando

I thought you were looking for a "premade cable", sorry if they didn't have an adapter, they do have most used cords. Plus, I would change the end, not the cable. Onnly had a second, enough time for the links, but not an explanation. Dinner was ready.

Yes I was planning on changing the end. I have a new L5-30 connector but don't know how to adapt from 4 wires to 3.

Hang on a second, I see the problem now. I misread your first post and thought you wanted an L6-30.

Are you sure of what you are trying to do? The original generator was feeding the transfer switch with 240 volts, 120 each side of the bus. The new, will only do 120 volts, period.

Do you have any 220 volt circuits or outlets fed by this panel? Maybe a well pump or something? If so, you can't do this and stop here.

Otherwise and let some of the electricians here say if it's OK to do this you need to jump the red and black together to feed circuits on both buses that come off the transfer switch.

The L14-20 is a 250v, 4 wire outlet rated at 20 amps.
The L5-30 is a 125v, 3 wire outlet rated at 30 amps.

Green to groud - blade with tab,
White to neutral - bigger blade, should have a W on it.
Red and Black together to smaller blade.

Quote:

Originally Posted by medic-dan

Hang on a second, I see the problem now. I misread your first post and thought you wanted an L6-30.

Are you sure of what you are trying to do? The original generator was feeding the transfer switch with 240 volts, 120 each side of the bus. The new, will only do 120 volts, period.

Do you have any 220 volt circuits or outlets fed by this panel? Maybe a well pump or something? If so, you can't do this and stop here.

Otherwise and let some of the electricians here say if it's OK to do this you need to jump the red and black together to feed circuits on both buses that come off the transfer switch.

The L14-20 is a 250v, 4 wire outlet rated at 20 amps.
The L5-30 is a 125v, 3 wire outlet rated at 30 amps.

Green to groud - blade with tab,
White to neutral - bigger blade, should have a W on it.
Red and Black together to smaller blade.

No 220 volt circuits on the panel. There is no "w" but the blades are marked by brass screw on the bigger (non-tabbed) blade, tabbed blade has a green screw, and the smallest blade has a silver screw.

This is very helpful. Since you indicated you're not sure I'll wait until someone else confirms.

Just to clarify, there are no 220 volt circuits on the transfer switch, but there are 220 volt circuits on the main panel that I don't consider critical in event of power outage (oven and central AC).

It'll work, my concern is just using the transfer panel this way. It's not really meant to do that. It's my concern over any 220 volt circuit that makes me nervous.

The colors are right, green to green screw.
White to brass
Red/Black to silver

Glad to have helped.

I should have stopped while I was ahead, I got my colors mixed up. Guess that's why I have a polarity tester in my home kit.

Are you sure the bigger blade has the silver screw? I wish I had one in front of me.

Standard outlet wiring is:

Green to green screw
White to silver
Red/Black to brass

Quote:

Originally Posted by medic-dan

I should have stopped while I was ahead, I got my colors mixed up. Guess that's why I have a polarity tester in my home kit.

Are you sure the bigger blade has the silver screw? I wish I had one in front of me.

Standard outlet wiring is:

Green to green screw
White to silver
Red/Black to brass

I wrote: "the blades are marked by brass screw on the bigger (non-tabbed) blade, tabbed blade has a green screw, and the smallest blade has a silver screw." Is that consistent with your expectation?

You are correct. I went out and checked my generator.

Why it is different than a standard 120 volt outlet (NEMA 5-15r) is beyond me.

Sorry to put you through this. It's been a long day.

Quote:

Originally Posted by medic-dan

You are correct. I went out and checked my generator.

Why it is different than a standard 120 volt outlet (NEMA 5-15r) is beyond me.

Sorry to put you through this. It's been a long day.

Now you have me confused... is yours different that it should be, or is mine?

You should NOT do this.

A) An L5-30 is a 120v receptacle. You have a 120/240v receptacle. Even though you may not have any 240v loads, the loads you have are balanced across two 120v legs.
By doing this you are placing ALL the loads on one 120v leg.

B) An L5-30 is a 30A circuit. You should NOT be feeding 15 & 20A circuits off a 30A circuit.
Without getting into the code aspect of it just know that it is not code legal.

I would find a generator with the proper L14-20 or L14-30 receptacle.

Yea, what stan said:

This should help:

NEMA Plug & Receptacle Configurations Reference Chart (Locking)

Mine is the same as yours. I meant, on a standard outlet the wide blade is neutral. On the L5-30, the narrow blade is neutral. Why the change by NEMA?

Regardless, listen to Stan and KISS. They say forget, so forget it.

Quote:

Originally Posted by stanfortyman

You should NOT do this.

A) An L5-30 is a 120v receptacle. You have a 120/240v receptacle. Even though you may not have any 240v loads, the loads you have are balanced across two 120v legs.
By doing this you are placing ALL the loads on one 120v leg.

B) An L5-30 is a 30A circuit. You should NOT be feeding 15 & 20A circuits off a 30A circuit.
Without getting into the code aspect of it just know that it is not code legal.

I would find a generator with the proper L14-20 or L14-30 receptacle.

Thanks stanfortyman. I won't question codes, but codes are meant to cover all possible scenarios and for the sake of the test of "reasonable application" I suspect what I want to do would still be safe. Based on what you wrote, perhaps I should think in terms of an adapter cord rather than replacing the L14-20 permanently.

Let me explain further and give more specifics:

I have been using a 4000-watt contractors generator (Generac Xl 4000) with the L14-20 connector. It is very loud.

For other more portable applications I have bought a Yamaha EF2000is inverter generator. It is only rated at 1600w continuous and 2000w peak, so by changing to a 30amp connector type there is no way it would overload the panel. In fact I would need to be very careful not to overload the generator. It is VERY quiet.

The only reason I chose a L5-30 is because the Generac also has one of those, and I already own an adapter cord to convert the L5-30 to standard 120v 15-amp straight prong grounded plug. That would let me switch between generators when I choose.

The only emergency load that might cause a concern to the Yamaha is the hot water circulator pump on the heating system, and inly during startup when it spikes to about 2200w for a few milliseconds. The pump only draws about 200w once it is running. I can't test whether the Yamaha will handle it unless I actually hook up the generator, as the circulator pump is hardwired.

All other loads are lights (mostly low-draw compact fluorescents) refrigerator (200w) and other arbitrary stuff for comfort and convenience (TV, computer, cordless phones, etc.) that are not heavy draw. (Other than the oven we cook with gas. Washer can be powered with the Generac if we had an extended outage, and dryer is gas.)

So in event of power outage the goal is to heat the house and keep the lights on with a much lower noise level, with less gas burned. I'm very aware of the limits of the 1600w Yamaha and have watt-meters on the transfer switch. I have tested power use with the Generac and my only concern is heating system startup -- so I figure the worst case is I'd trip a protection circuit on the Yamaha and rule out this whole idea -- sticking with the Generac if it's needed during the heating season.

So if the specifics aren't creating a safety hazard it seems like a good idea to me. Your further thoughts, all things considered?

One more thing, the connector at the transfer switch end is L14-30.