30 amp generator receptacle/20 amp Transfer switch

Thread Starter

hunt.family5

Joined Aug 31, 2020
8
Good Day, I tried the search but I couldn't figure out how to work it. I clicked "search" and nothing happened. so sorry if this could have easily been answered with a search.

My mother's generator has crapped out. It's a 5,000 running (not running) watt gen with a 20 amp 4 prong receptacle. So I installed (prior to knowing the gen crapped out) a transfer switch with a 20 amp 4 prong male end. Now that the gen has crapped out, I can't seem to find a 5,000 watt generator with a 20 amp 4 prong receptacle. they have all had 30 amp 4 prong receptacles.

Can I safely use an adapter from a 30 amp cord to the 20 amp 4 prong transfer switch?

i really don't want to buy another transfer switch.

Thanks in advance
 

MrSoftware

Joined Oct 29, 2013
2,011
The question is; can the generator you choose over-power than 20A receptacle? If it can, then an adapter is a bad idea. That said; also check if the transfer switch has a 20A or smaller main breaker, that would trip should the 20A receptacle be over powered. Also a choice B; you can add a 30A receptacle direct to a dedicated breaker in the main panel, and install an interlock such that the generator and main line breaker cannot be enabled at the same time. There are interlock kits all over the interwebs.
 

Thread Starter

hunt.family5

Joined Aug 31, 2020
8
The question is; can the generator you choose over-power than 20A receptacle? If it can, then an adapter is a bad idea. That said; also check if the transfer switch has a 20A or smaller main breaker, that would trip should the 20A receptacle be over powered. Also a choice B; you can add a 30A receptacle direct to a dedicated breaker in the main panel, and install an interlock such that the generator and main line breaker cannot be enabled at the same time. There are interlock kits all over the interwebs.
http://www.reliancecontrols.com/ProductDetail.aspx?20216A
i don't believe it has a main breaker.
 

Reloadron

Joined Jan 15, 2015
5,897
A general answer is yes, as long as you do not exceed certain limits. This would go much better if you either pictured what you have and where you want to go, point to point. Additionally terms like 3 prong or 4 prong don't say much. You may want to look at a NEMA chart or plugs and sockets so you can better describe exactly what you have. Also the voltages involved?

Nothing is likely to blow up or melt as long as the loads are behind a proper circuit breaker.

Ron
 

Thread Starter

hunt.family5

Joined Aug 31, 2020
8
A general answer is yes, as long as you do not exceed certain limits. This would go much better if you either pictured what you have and where you want to go, point to point. Additionally terms like 3 prong or 4 prong don't say much. You may want to look at a NEMA chart or plugs and sockets so you can better describe exactly what you have. Also the voltages involved?

Nothing is likely to blow up or melt as long as the loads are behind a proper circuit breaker.

Ron
Don't have the generator yet as we can't find one that has a L14-20P receptacle defining my issue.
don't really want to buy another transfer switch therefore trying to figure out IF i can use the one we have with a generator that has the L14-30 outlet.
Untitled.jpg
 

Reloadron

Joined Jan 15, 2015
5,897
Your transfer switch should have a single breaker at entry point. It would be between the inlet of transfer switch and all of the sub circuits (branch circuits). They make adapters to do what you want to do or you can just roll your own. You are going from a NEMA L14-30P Plug at the generator to what should be a L14-20R (Receptical) to connect to the transfer switch. The P designations are Plugs and the R designations are Recepticals. You want something like this if I read all of this correctly. That example uses 12/4 SOOW cable which is rated for 20 amp service, if I were to roll my own I would likely opt for AWG 10 wire rather than 12 if my generator had a 30 amp breaker on the output.

Ron
 

Thread Starter

hunt.family5

Joined Aug 31, 2020
8
Your transfer switch should have a single breaker at entry point. It would be between the inlet of transfer switch and all of the sub circuits (branch circuits). They make adapters to do what you want to do or you can just roll your own. You are going from a NEMA L14-30P Plug at the generator to what should be a L14-20R (Receptical) to connect to the transfer switch. The P designations are Plugs and the R designations are Recepticals. You want something like this if I read all of this correctly. That example uses 12/4 SOOW cable which is rated for 20 amp service, if I were to roll my own I would likely opt for AWG 10 wire rather than 12 if my generator had a 30 amp breaker on the output.

Ron
i've seen the adapters. i'm just not sure how safe it is. below is the transfer switch (except it shows a 30 amp plug in the pic)
I don't see a separate breaker for the input unless its inside.
20216A.jpg
 

Lo_volt

Joined Apr 3, 2014
153
What is the rating of the circuit breaker on the generator? If it is 20 amp or less then there is no issue. Your 20 amp transfer switch is protected by the 20 amp breaker on the generator.

That being said, I think a 5000 watt generator will likely have a 25 or 30 amp circuit breaker on it. So your best low-cost option is to add the stand-alone breaker as MrSoftware said. Note that you will use the 30 amp plug to the generator and 10 AWG wire to the stand-alone breaker. 10 AWG is rated for use at 30 amps.
 

Thread Starter

hunt.family5

Joined Aug 31, 2020
8
What is the rating of the circuit breaker on the generator? If it is 20 amp or less then there is no issue. Your 20 amp transfer switch is protected by the 20 amp breaker on the generator.

That being said, I think a 5000 watt generator will likely have a 25 or 30 amp circuit breaker on it. So your best low-cost option is to add the stand-alone breaker as MrSoftware said. Note that you will use the 30 amp plug to the generator and 10 AWG wire to the stand-alone breaker. 10 AWG is rated for use at 30 amps.
yeah we don't have the Gen yet as we trying to find one with a 20 amp receptacle but have not been able to.
 

MrSoftware

Joined Oct 29, 2013
2,011
didn't think about that................so i would take the cord into a single 20 amp breaker and then to the transfer switch?
Yep. Since your transfer switch appears to be rated for 20A max, going by the plug, you'll want a 20A breaker somewhere between the generator and the transfer switch. Also contact the transfer switch company, ask them if their switch box will actually handle 30A. Maybe the box itself will handle more than the inlet they provided with it. If yes, then just swap the inlet on the transfer switch.
 
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