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Old 07-17-2012, 02:29 PM   #1
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Generator to Home wiring...


I'm looking for ideas, we're in the middle of upgrading our home's generator and wiring...

First, the background info...
After Irene, we bought a Duromax 3.5kw/4.4pkw portable generator plugged into a 30amp inlet box attached to the masonry of our home, wired via 10/3 UF-B cable to a Reliance 8kw 10 circuit transfer switch.

After the freak Derecho weather pattern + heat wave and a 6 day black out... we decided we needed at least one more circuit added... the central A/C... So, we upgraded to a Generac gp17500e 17.5kw / 26.5pkw portable generator, upgraded the inlet cable to 6/3 NM-B inside PVC conduit, wired into an 8 slot sub panel in parallel with the existing 10 circuit transfer switch. In the sub-panel, is a 20amp double pole breaker whose output goes to one side of a Leviton 1288 30amp double pole/double throw, center-off, individual transfer switch, which wired to the A/C outside. The furnace fan was already wired via the 10 circuit transfer switch. We haven't upgraded the inlet box to a 50 amp socket, yet.

This setup easily powers the whole transfer switch plus the A/C, all off the generator's 30 amp outlet. Keep in mind, this new generator can put out ~71 amps continuous.

After testing out the new generator for abit we decided to build a shed to enclose it and quiet it down. The shed will have a secondary muffler ported out one side of the shed for the gas exhaust and adequate inlet ventilation and a 1500cfm gable vent fan for ambient heat blowoff.

With all that said...
Challenge is, since the planned shed won't be near the current inlet box, I'll have to make a new run from the house to the generator. Currently I'm thinking I'll have to:

A) Punch a new whole either in my masonry foundation or the rim joist, just above it.

B) Attach an appropriate sized blank PVC junction box to side of house with one short piece of 1.25" PVC coming through hole, and a run of 1.25" PVC tubing, with curved pieces where needed, down the foundation wall and along my fence, at it's base, to the generator. I would terminate the tubing at the shed with a 90 degree PVC piece. This run would not be buried underground but run along the ground, behind bushes.

C) I would pull 3 individual #6 THWN wires for the two hots plus neutral. Would pull bear (#10 ?) copper for the ground. These would connect, at least, to the generator's 50amp socket, or possibly the 30 amp and 50 amp in parallel. The generator does not seem to have an obvious / clean way to extract all 71 amps via one single socket or connection (odd...). So I believe with a parallel connection I'll be able to draw about 60amps continuous. Which should be good for 6 AWG cable.

D) Was also considering pulling additional #10 THWN wires (hot, neutral, another(?) bear copper ground), on it's own circuit breaker to have an 120V outlet, coming from the house, to the shed. This would allow for things like a trickle charger for the generator's starter battery.


What do you guys think about this? Looking for correction/alternatives if needed. Thanks in advance!


Last edited by ngcreese; 07-17-2012 at 03:05 PM.
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Old 07-17-2012, 03:37 PM   #2
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Generator to Home wiring...


tl;dr

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Old 07-17-2012, 03:46 PM   #3
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Generator to Home wiring...


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Originally Posted by TarheelTerp View Post
tl;dr
Lol!!

Ok the short version...

Can you run #6 THWN cables inside PVC ridgid tubing outdoors, along the ground, without burying it, as long as it's out of the way? For me, that would be along the bottom of a fence line.

Sorry for the longer post above...
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Old 07-17-2012, 04:08 PM   #4
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Generator to Home wiring...


Using both receptacles on the generator in parallel is a bit of a safety issue. If you remove one plug while the other is plugged into the generator, the prongs of the plug will be energized.

That 50 amp outlet will handle intermittent loads over 50 amps without any problem. Do you really need to run more than 50 amps continous into your generator panels? If you do I hope you have lots of gasoline stored up.

The are really only two ways to use to do what you want to do. The first is to go to pin and sleeve connectors. They make a 120/240 volt 100 amp inlet and matching connector. They cost about 650 for both.

The other way, which is probably better for you, is to hardwire the generator inside the shed and bypass the connectors completely.

You also might consider wiring in a themal switch into the kill circuit of the generator. If it gets too warm in the shed, the thermal switch would open the ignition circuit and stop the generator before it cooks itself.
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Old 07-17-2012, 04:39 PM   #5
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Generator to Home wiring...


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Originally Posted by Auger01 View Post
Using both receptacles on the generator in parallel is a bit of a safety issue. If you remove one plug while the other is plugged into the generator, the prongs of the plug will be energized.

That 50 amp outlet will handle intermittent loads over 50 amps without any problem. Do you really need to run more than 50 amps continuous into your generator panels? If you do I hope you have lots of gasoline stored up.

The are really only two ways to use to do what you want to do. The first is to go to pin and sleeve connectors. They make a 120/240 volt 100 amp inlet and matching connector. They cost about 650 for both.

The other way, which is probably better for you, is to hardwire the generator inside the shed and bypass the connectors completely.

You also might consider wiring in a themal switch into the kill circuit of the generator. If it gets too warm in the shed, the thermal switch would open the ignition circuit and stop the generator before it cooks itself.

Yeah, I think I'm just going to go with the 50 amp plug. Else, as you've pointed out, I'll have to go in and do a hard wire setup. According to the schematics, it looks like there's a bus in there that must be able to handle a full power draw.

For the planned setup... I'll take the individual #6 THWN wires into a l14-50p plug head... or doctor one of those replacement l14-50p appliance plug head & wire lead thingies that they sell at lowes / homedepot.

We went with a genny this big, cause the next one down (gp15000e) consumed the same amount of fuel for less power output, and the one below that (xg/xp10000e) was too small, to start the A/C.

I hear you on the fuel...

Funny enough, although I wouldn't have to deal with the refueling issue, natural gas turned out to cost as much, or more than, gasoline...

On the flip side... after my wife and I experienced the complete sell out of almost every hotel room in our portion of the state. And the ridiculous price gouging of what was left... ( $600 per night... for a room at the Best Western...)... the fuel costs didn't seem as bad... lol!!!

Thermal cut off of the generator is a great idea, didn't think of that, Going to have to add that to the list!

Last edited by ngcreese; 07-17-2012 at 04:52 PM.
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Old 07-17-2012, 04:47 PM   #6
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Generator to Home wiring...


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Funny enough, although I wouldn't have to deal with the refueling issue, natural gas turned out to cost as much, is not more than, gasoline.
It's worth not having to make the gas runs and worry about keeping your stock fresh.
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Old 07-17-2012, 04:48 PM   #7
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Generator to Home wiring...


i know a place that runs a banquet hall off a 50A genny, the disco balls might not turn but the beers still cold. i really don't think you need to go bigger than that
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Old 07-17-2012, 04:54 PM   #8
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Generator to Home wiring...


the generator has a 50A twistlock on it already, you need to get yourself a male end and a female end. make yourself a cord to plug into the twistlock(a range plug won't work) then you need to get one of these.
http://www.electricgeneratorsdirect....B50/p1092.html
you can run from the inlet box to your house with the 6/3 cable if you want after that. Also without the proper ventilation you can't have your genny running in the shed i don't believe. Most people build mini sheds with removable walls to allow airflow or you can just pull it out of the shed while it's running.
I dont recommend doing a direct connect because your bypassing the genny's gfci protection and voiding the warranty
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Old 07-17-2012, 04:56 PM   #9
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Generator to Home wiring...


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Originally Posted by zappa View Post
It's worth not having to make the gas runs and worry about keeping your stock fresh.
...and, TBH, I couldn't stomach the up-front/all-at-once install cost of a NG version.
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Old 07-17-2012, 05:01 PM   #10
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Generator to Home wiring...


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Originally Posted by ngcreese View Post
...and, TBH, I couldn't stomach the up-front/all-at-once install cost of a NG version.
Oh....I misread. I thought you did go with NG.
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Old 07-17-2012, 05:12 PM   #11
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Generator to Home wiring...


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Originally Posted by andrew79 View Post
the generator has a 50A twistlock on it already, you need to get yourself a male end and a female end. make yourself a cord to plug into the twistlock(a range plug won't work) then you need to get one of these.
http://www.electricgeneratorsdirect....B50/p1092.html
you can run from the inlet box to your house with the 6/3 cable if you want after that. Also without the proper ventilation you can't have your genny running in the shed i don't believe. Most people build mini sheds with removable walls to allow airflow or you can just pull it out of the shed while it's running.
I dont recommend doing a direct connect because your bypassing the genny's gfci protection and voiding the warranty
Rgr that...

Have (what adds up to...) 2.614 sqrft opening on one end of shed... and a 16" diameter 1500 cfm attic vent fan at other end...

Will go with a raw l14-50p plug head into #6 cables...

Last edited by ngcreese; 07-17-2012 at 05:47 PM.
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Old 07-17-2012, 05:17 PM   #12
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Generator to Home wiring...


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Originally Posted by andrew79 View Post
i know a place that runs a banquet hall off a 50A genny, the disco balls might not turn but the beers still cold. i really don't think you need to go bigger than that
In truth all our current stuff ran off the genny's 30A twistlock... the the 50A will just give us a lot of head room.
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Old 07-17-2012, 05:17 PM   #13
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Generator to Home wiring...


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Originally Posted by andrew79 View Post
the disco balls might not turn but the beers still cold.
I'm glad to see they have their priorities straight!
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Old 07-17-2012, 05:38 PM   #14
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Generator to Home wiring...


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Originally Posted by ngcreese View Post
Rgr that...

Have a 2.614 sqrft opening on one end of shed... and a 16" diameter 1500 cfm attic vent fan at other end...

Will go with a raw l14-50p plug head into #6 cables...
if i've read through all this right i sense that you plan on putting individual wires into a male cord end and plug that into your genny. I'm not even going to bother counting the rules that's going to break. At least come into a box first and switch to cabtire cable.
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Old 07-17-2012, 05:56 PM   #15
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Generator to Home wiring...


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Originally Posted by andrew79 View Post
if i've read through all this right i sense that you plan on putting individual wires into a male cord end and plug that into your genny. I'm not even going to bother counting the rules that's going to break. At least come into a box first and switch to cabtire cable.

I'm totally tossing my genny shed plan in this forum, for review/correction/opinions... so I can go down the best path...

Put a different way, I'm looking for the things I haven't given enough consideration too.

Sounds like I want to bring the THWN wires into a junction box inside the shed, then switch over to a wrapped 6/3 cable and attached that to a l14-50p plug head.... sounds good to me.


Last edited by ngcreese; 07-17-2012 at 06:03 PM.
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