30A DPDT Switch question

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Northwestsparky

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Electrician
Hi everyone,

always looked for answers on here but never posted.

Im curious about using a 30A DPDT for the use of a GP17500E portable generator to be able to get the full potential of the generator power. Since the 50A is only good for 12,500 continuous, can i use the 30A / 240V on the generator strictly for the AC compressor with this switch? This would allow for the biggest load in the home especially at startup to be isolated from the 50A. Then the 50A could just be used for the general lighting, refers, microwave, and possibly a burner on the stove. Has anyone done this? If I'm looking at this correctly the DPDT is basically a transfer switch that could be used from utility or generator power. This would keep from back feeding the power to the utility like a interlock kit but just for the compressor.

Thank you
Chris
 
drcampbell said:
A toggle switch doesn't have as much internal separation as a transfer switch. It might have an undesirable failure mode.
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I was actually thinking of the

Siemens DTNF221 30-Amp 2 Pole 240-volt.​

Don’t have any experience with this product, but maybe someone out there has.
 
The UL listing for snap switches does not allow this switch to be fed from 2 sources. They are only listed for 1 source, 2 loads. Also does not meet the requirements for a transfer switch.
 
Aside from the technical reasons cited above what are you really gaining by adding the extra layer of complexity?

You want to take the largest load off the largest recpt on the generator and use it to run the microwave for forty seconds three times a day and the nine amps worth of lighting loads in the rest of the house consumes during the outage?
 
texie said:
The UL listing for snap switches does not allow this switch to be fed from 2 sources. They are only listed for 1 source, 2 loads. Also does not meet the requirements for a transfer switch.
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I wasn’t referring to a snap switch, looking for information on the DPDT Siemens DTNF 221.
 
ActionDave said:
Aside from the technical reasons cited above what are you really gaining by adding the extra layer of complexity?

You want to take the largest load off the largest recpt on the generator and use it to run the microwave for forty seconds three times a day and the nine amps worth of lighting loads in the rest of the house consumes during the outage?
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Just a thought as it would allow loads like a burner or two without tripping the 50A breaker at the generator when AC kicks on.
 
Keep in mind that multiple outputs from a generator are merely internally paralleled from a single set of coils.
 
LarryFine said:
Keep in mind that multiple outputs from a generator are merely internally paralleled from a single set of coils.
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The GP17500E is capable of 17500 continuous and 26500 startup. Just want to be able to use the generators potential output when needed. Not saying max out to 17500 but possibility of using burners on a stove or hot water while ac is starting or running. If all these things were on just the 50 the breaker would trip
 
ActionDave said:
Aside from the technical reasons cited above what are you really gaining by adding the extra layer of complexity?

You want to take the largest load off the largest recpt on the generator and use it to run the microwave for forty seconds three times a day and the nine amps worth of lighting loads in the rest of the house consumes during the outage?
Click to expand...
In Florida the AC is always kicking on and off, would like to separate that from the 50a if this option is possible with this size generator. In case of a power loss the option to use a burner or two or the oven would be nice instead of tripping the breaker on the generator when the ac kicks on.
 
It sounds like you have a generator capable of about 70A continuous output and more than 100A for starting, but which has no single full output receptacle.

You are essentially trying to jerry rig a second transfer switch to use this capacity.

I'd contact Generac to see if there is some option or accessory to provide a suitable single larger receptacle, or a way to hard wire this generator.

Jon
 
winnie said:
It sounds like you have a generator capable of about 70A continuous output and more than 100A for starting, but which has no single full output receptacle.

You are essentially trying to jerry rig a second transfer switch to use this capacity.

I'd contact Generac to see if there is some option or accessory to provide a suitable single larger receptacle, or a way to hard wire this generator.

Jon
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Jerry rig, No. just trying to utilize the 50A and the 30A as the generator specs and not voiding warranty. Just thinking outside the box but still within the NEC, most are just so stuck on one track.

i was thinking of using the interlock kit for the 50A and then using a DPDT for the AC. Then the capability of using a couple burners or the oven is a possibility during a power outage since the ac load will be separated from the 50A
 
Ok, not jerry rig, but still: provide two transfer switches to overcome the generator receptacle limitations.

IMHO the sort of switch you suggested in the opening post is the sort you would need. You specifically need something suitable as a transfer switch.

An additional consideration is parallel neutral paths. If you are absolutely certain that you will only run 240V loads with this second receptacle, then a two pole switch is fine. But if you want to have the flexibility of running 120V loads then you should look at a 3 pole double throw and switch the neutral.

If you don't switch the neutral then you have a parallel neutral path from generator to loads.

Jon
 
winnie said:
Ok, not jerry rig, but still: provide two transfer switches to overcome the generator receptacle limitations.

IMHO the sort of switch you suggested in the opening post is the sort you would need. You specifically need something suitable as a transfer switch.

An additional consideration is parallel neutral paths. If you are absolutely certain that you will only run 240V loads with this second receptacle, then a two pole switch is fine. But if you want to have the flexibility of running 120V loads then you should look at a 3 pole double throw and switch the neutral.

If you don't switch the neutral then you have a parallel neutral path from generator to loads.

Jon
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Thank you Jon
 
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