Powering home with generac 15kW generator

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Old 07-09-17, 06:33 AM
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Powering home with generac 15kW generator

I just purchased a used guardian ultra source 15kW (22kW surge) generator. I am hoping to install an interlock on my Siemens panel in order to gain access to all circuits as opposed to a transfer switch and only have a few.

I'm fairly new to generators and am wondering about the inlet box I should purchase. I see that the genny has a 50amp outlet and a few 30s. Am I supposed to put a 50amp inlet and then 50amp breakers in the panel? Wouldn't that hold me to 12kW max? How should I hook it up in order to have access to its full power?
 
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Old 07-09-17, 06:58 AM
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The straightforward wiring procedure for home use uses the 50 amp receptacle on the generator and limits you to 50 amps (perhaps plus a margin for starting surge of some appliances) or 12 KW, all at 240 volts. Use a 50 amp inlet, 50 amp transfer switch, and 6 gauge wiring to the home electrical system.

Use of the generator out in the field (such as at a construction site) would have more than one generator receptacle in use allowing full use of the 15 KW capability.

Check the generator instructions for lug connections that bypass the receptacles and therefore can be used to draw the full 15 KW.

You, too, could use a 30 amp receptacle on the generator together with a portable subpanel (glorified power strip) with 15 and/or 20 amp breakered ordinary receptacles for some lights and appliances connected with extension cords while also using the 50 amp generator receptacle to feed the home electrical system and get a total of 15 KW out of the generator.
 
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Old 07-09-17, 07:06 AM
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Note that if you use lug connections in the generator you must have breakers or other overcurrent protection, either in the generator or elsewhere, to prevent drawing more than 15 KW continuously from the generator.
 
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Old 07-09-17, 07:27 AM
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Not sure on the lug situation, but I will check it out. I really appreciate the replies, Allen. I'm sure this is a dumb question because to me it sounds sketchy, but could you wire the 50amp outlet - 50amp inlet- 50 amp breaker in panel and also wire the 30amp outlet - 30amp inlet - 30amp transfer switch or is that overkill? I was hoping to avoid extension cords as I prefer a "clean" install
 
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Old 07-09-17, 09:27 AM
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What is the model of your panel? there may be a transfer switch you can add to your panel.
 
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Old 07-09-17, 09:32 AM
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P4040B1200

I found the ECSBPK03 interlock that I was hoping to use for this.

Does the 50amp connection still allow for surge watts? I'm wanting to use my 4 ton central A/C
 
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Old 07-09-17, 10:57 AM
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If you main breaker is a MBK200A or MBK200M I would think that interlock would work for your panel. The breaker you install for the generator in the panel should be no larger then 50 amp as you will be coming off the 50 amp receptacle on the generator. There is no way to "double up" the receptacles to have 15kw available, however, that is likely a good thing as most cases you do not want to fully load a generator anyway. Circuits breakers are time delay so a surge load should not be an issue.

Or do what Allen posted, adding another sub panel that will be fed off a separate inlet/cord/receptacle of the generator.

IMO - It likely won't be worth the trouble as you have 12,000 watts available. You should add up the items you will have running using the nameplate info, not the breaker size. Then calculate the total watts. It would also be a good idea to balance the load between legs as much as possible.
 
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Old 07-09-17, 12:50 PM
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Does the 50amp connection still allow for surge watts? I'm wanting to use my 4 ton central A/C
The surge rating is a fictional figure. It's a loosely arrived at figure for motor starting.

Can you run your 4 ton A/C.... most likely yes..... but that's about it. The generator unloaded will be needed to start the compressor. Once it's running you should be ok.
If it reaches temp and shuts down..... you'll need to shed load before a restart.

Every generator handles motor start up differently. You'll need to see how yours is.
 
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Old 07-09-17, 02:06 PM
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Good information. Thanks guys.
 
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