standby generator install...some questions

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  #1  
Old 11-21-15, 12:12 PM
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standby generator install...some questions

I want to install a standby generator at my house. It will be one of those Generac 16k units, LP fueled. I had arranged for an electrician to come out
and do the work, and he was a no show. I have had no luck getting anyone else to be able to commit before winter, so I was contemplating taking on the initial install piece myself. Assuming I can arrange for getting a unit delivered and set on a concrete pad, I need some help with some things, and then I'll hand it off to an electrician who won't have much work to do other than wire the transfer switch to the main panel, something I'd rather let a pro handle. But I feel if I can get a good feel for what materials I need to get all the parts and pieces in place, I would like to try doing the bulk of the work. The generator will install on a pad that is next to a pedestal where the LP feed has already been trenched and mounted. So at this point all I need from propane tech is the final connection from their regulator to the generator once its in place. As far as electrical, I have an 2" underground conduit coming up behind the pad location. This conduit runs underground approximately 30 feet and comes up next to the outside wall of my garage, which is attached to the house. So my first question is needing to know what type of wire I need to run through this conduit to attach to the generator, and I would assume I'd have some type of electrical box on the garage side to terminate this wire. Then I would assume I'd need a 2nd wire to run from this connection box up and over the garage trusses across the garage and down into the utility room inside the house where the main panel and future transfer switch are located. If that assumption is correct, what type of wire would this involve? From here I'd just bring the wire that will connect to transfer switch into the house and then I'd let a licensed electrician do the rest. Am I missing any steps or do I need to do something differently? To summarize, I basically need to know what wire to run through the underground conduit from generator, what type of mounting box would I attach to side of garage to join the underground wire with the wire running inside the garage down into the transfer switch. Any help would be greatly appreciated.
 
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Old 11-21-15, 01:44 PM
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Good luck in finding an electrician that will allow you to supply the wire and pull it through the conduit to the connection points. Most won't because of liability issues.

For detailed instructions on the generator installation I suggest that you get the installation manual for the generator you plan on using. I strongly suspect that you will need a second conduit between the generator and house for the control and maybe a third conduit for the battery charger and crankcase heater.

You will need continuous conduit from the generator pad to the transfer equipment and if there are more than the equivalent of four 90[SUP]o[/SUP] bends in the conduit you will need to have some access or "pull" points to break it up so that no section has more than the allowed four bends.

The type of wire insulation will be type THWN or more likely it will be dual rated as THHN/THWN. Size is dependent upon generator output and total length of the run. For a 16kW gennie with a run of less than 100 feet total the size would be #4 copper although you might be able to use #6 with special permission from your LOCAL inspector. I personally would use the #4. You could also use #3 aluminum. The equipment grounding conductor could be as small as #8 copper or #6 aluminum. More likely as not the local inspector will want a grounding electrode at the generator pad.

A short piece of liquidtite flexible conduit from the stub-up at the generator pad to the generator proper is required to allow for the vibration of the generator and to prevent the PVC conduit from breaking. If you have multiple conduits then all will require this flexibility.
 
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Old 11-21-15, 03:34 PM
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Not an easy first time install. Furd left you some good advice.

You will need a second smaller conduit for control wiring/battery charging.
With some larger gensets like that.... the electrical conduit needs to come thru the pad.
 
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Old 11-21-15, 06:06 PM
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thanks for the replies. I'm confused on some things:

"Good luck in finding an electrician that will allow you to supply the wire and pull it through the conduit to the connection points. Most won't because of liability issues."

So if I did all the prep work and called up an electrician saying I'd like the auto transfer switch connected to the main panel, they would be hesitant to do so because they were not involved in the rest of the setup?

"For detailed instructions on the generator installation I suggest that you get the installation manual for the generator you plan on using. I strongly suspect that you will need a second conduit between the generator and house for the control and maybe a third conduit for the battery charger and crankcase heater."

the electrician that was a no show came out and spec'd out my setup, and knew I had only a single conduit. He gave no indication any further prep work would need to be done on my part, as far as an extra conduit or anything else, so I'm confused. What is the "control" you refer to as well as the battery charger and crankcase heater? where would those wires go? I can tell you that if another conduit is needed, then this project is going to be declared dead, as there is no way I'm going to trench up the yard again.

And as far as your comment on a continuous conduit, it sounds as though you mean that there is no break in the connection between where it comes out of the conduit next to the garage and where it goes into the garage and all the way down to the panel, that its just a continuous cable the whole way. did I understand that right? And that #4 wire you suggest is what would interface with the auto transfer switch? I noticed that some transfer switches come with a 'pre-wired' transfer switch. would that still be relevant in my case? and would you be so kind as to give me a link or product desc of the correct #4 wire so I make sure I am looking up the right one?

thanks so much for your help.
 
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Old 11-21-15, 06:26 PM
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I install a lot of generators. In most areas..... especially here in NJ..... since the explosion of installations after the big storms...... the towns are cracking down on all phases of installations. Here we are required to file for a permit for gas, electric and fire inspection. Load calculations must be done. Plot plans issued as well as plans for generator pad.

Coordination with the gas company can be like pulling teeth.
The electrical inspector may need to see the conduit before back filling. (I know yours is done)

The generator companies specify minimum of two conduits to keep the control wiring separate from the mains power wiring. The inspector is supposed to check this. Most do.... some don't.

A ground rod is not required at the generator.

If you are using a service rated transfer switch then you are required to convert your main electrical panel to a sub panel. That requires all the neutrals to be separated from the grounds.
 
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Old 11-22-15, 08:39 AM
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Generac approves the wiring in the same conduit if the insulation is rated appropriately. You can find the install manual online with a bit of searching, if you don't have your generator yet.
 
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