Transfer Switch Question

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  #1  
Old 03-18-13, 10:38 AM
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Transfer Switch Question

I have what I believe is a simple question, but really was hoping to have the opinions of a few experts…..

I have a Coleman Powermate 110/220VAC 7200W transfer switch. It is fed through an L14-30 connector. The generator I’ve used with it is a 6500 110/220VAC Coleman. The ONLY things that are wired to this transfer switch are 110VAC devices.

My question is pretty simple. If I wanted to use a small 110VAC 1600W generator (or possibly two in parallel), would there be anything wrong with feeding the line voltage into BOTH of the line pins on the transfer switch input connector? It seems to me this would allow me to put the 110VAC on both sides of the transfer switch at the same time. Obviously I would lose a lot of power capacity doing it this way, but if the sum total of the power being pulled from all the loads on both sides of the transfer switch didn’t exceed the output power of the generator would it work? I could easily accomplish what I’m talking about by properly (or perhaps I should say improperly) wiring the connector that goes into the transfer switch.

Why would I want to do something so stupid? The 6500W Coleman is a beast, and runs loud enough for the wake the dead. The little Honda and Yamaha 2000W generators run so much quieter, and would be much easier to store. But of course, they are only 110VAC generators, not the 110/220 version. I would also appreciate the idea of being able to take them camping, something that would be impossible with the 6500W version.

Any reason (safety or otherwise) that what I’m saying wouldn’t work?
Given the power I’m inputting to the transfer switched is “switched away” from the breaker box, I shouldn’t have to do anything other than throw the main breakers in the box, correct? I’m thinking I don’t need to even touch the 220VA breakers in the breaker box, right?

Thanks!

Tom
 
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  #2  
Old 03-18-13, 10:54 AM
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Any generator setup is going to need a transfer switch or an interlock at the service panel.

If you want to use the smaller generators I would suggest just using extension cords to the loads you want to power.
 
  #3  
Old 03-18-13, 11:05 AM
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Understood, but I would prefer using the transfer switch since I already have it wired into 10 different circuits throughout the house. Granted, I wouldn't be able to drive a ton with the smaller generators, but should be OK to wire the single hot out of the generator into the both line-in pins on the transfer switch plug?

Thanks!
 
  #4  
Old 03-18-13, 11:24 AM
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It is possibile to do what you want, but there are a few things thats need to be done first. Trun off all 240v loads. Do you have any Multi wire branch circuits? If you do, they shouldn't be used. If you dont know what those are, google it.
 
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Old 03-18-13, 11:27 AM
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You might overload the neutral by doing so.
 
  #6  
Old 03-18-13, 12:19 PM
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You could not run two generators in parallel. They would not be phase aligned and would burn up.

As long as you only have 120 volt loads, I would think connecting the 120 volt generator to both phases would work. But with 10 load circuits, you will need to turn off some to limit your 2 Kwatt generator.
 
  #7  
Old 03-18-13, 12:49 PM
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They used to make a 120v only transfer swith. It was limited to 3700 watts. I assume you overload MWBC and that is close to the limit on wattage.

30116V Gen Tran 30 Amp 6 circuit 3750 watt

Then you get the proper L5 inlet.

Gentran Corporation: Generator Transfer switches for home & business

Now they make one as a panel for 120 volt only.

Amazon.com: GenTran 300660 30-Amp 6-Circuit Manual Transfer Switch for Generators up to 3750-Watt: Patio, Lawn & Garden

Essentially, and I dont know the code implications, but I tied the two hots togther in my transfer switch. Changed my inlet to an L5. I have no 240 loads. I run a 3250 watt 120v only gen to power my loads.

Let the electricians chime in if this is allowed.....
 
  #8  
Old 03-18-13, 01:07 PM
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If you are talking about Honda gennies....why not just consider adding a parallel kit and connecting both to the existing panel?

Not sure if that would work or not, but my neighbor did that so he could run the A/C on his RV when he was out in the wild.
 
  #9  
Old 03-18-13, 01:36 PM
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To run 2 gensets you would need a parallel means to sync both.
 
  #10  
Old 03-18-13, 03:39 PM
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1600W or 3200W really isn't the issue. It's just more power. My concern is just if it's safe to put 120VAC across both hots.

Thanks!
 
  #11  
Old 03-18-13, 03:42 PM
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What transfer switch do you have? Possibly the wiring cant handle the additional amps.
 
  #12  
Old 03-18-13, 03:50 PM
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Coleman Powermate. 30A Max input. 7200W 10 switches.
 
  #13  
Old 03-18-13, 04:20 PM
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Im not an electrician so not sure.

But the 30 amp at 240v is 7200w. At 120 thats 3600w. That would be the biggest 120v only gen you could run....

As far as tieing the hots toghther I think its allowed, but you need to change the inlet to an L5. What size wire is run from the inlet to transfer switch? 10 gauge?. When you rewire I belive you can still use the 3 wire but not use the red/hot wire.

Also as I found out you need a large wire nut to tie the hots together.

The electricians need to give you the definite answer.
 
  #14  
Old 03-18-13, 05:27 PM
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You would really have to try hard to burn up a neutral with 2000 watts.
 
  #15  
Old 03-19-13, 04:02 AM
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Here is a basic question. I have a 7 Kw 240 volt generator that powers 10 circuits and only one is 240 volt (well pump). The rest are all 120 volt circuits. Is it the fact that each leg is 180 degrees out of phase that the neutral line carries little current?

Instalation said to use 10 AWG wire but I used 8 AWG because the cost was almost the same.


edit:
After thinking about this, I see why the 240 volt generator has less current on the neutral line. The 120 volt loads on one phase would "buck" the 120 volt loads on the other phase and result in no neutral current flow if they matched.

So the 2 Kw 120 volt generator could have a maximum neutral current of 16.7 amps. Should be pretty safe with 10 AWG wire
 

Last edited by DMCman; 03-19-13 at 05:56 AM.
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