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Backup Generator - Wiring from Inlet Box to Transfer Switch

Backup Generator - Wiring from Inlet Box to Transfer Switch

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  #1  
Old 07-10-14, 03:40 PM
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Backup Generator - Wiring from Inlet Box to Transfer Switch

I am having an electrician do the below work. They will be installing a backup power generator system for me.
I have a backyard shed ~150 feet from my house/basement electrical panel.
I have a generator (capable of 30 amps). I will likely buy a bigger one. (50 amps
I am having a power inlet box installed in the shed.
I am having a trench dug ~24 inches deep shed to house at basement panel.
I am having a manual transfer switch installed in the basement next to the main electrical panel.

What size wire is necessary to run from the shed to the transfer switch to accommodate the bigger generator I'm thinking of buying?
 
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  #2  
Old 07-10-14, 06:01 PM
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Welcome to the forums.

Personally, I'd be running #6 conductors.
Three #6 THWN (two hots and a neutral) and one #10 THWN (ground) in a 1" or 1-1/4" PVC conduit.
 
  #3  
Old 07-11-14, 04:57 PM
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Thanks. Thinking of upgrading to Generac Model 5735, 17,000 Watts, 73Amps @240 volts. Is the wiring recommendation the same?
 
  #4  
Old 07-11-14, 05:07 PM
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In that case it may be advisable to upsize to #4's for your hots and neutral.
 
  #5  
Old 07-11-14, 05:17 PM
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You're the best, thanks. Friday night 7:15 PM and you're providing answers. I'm having an inground pool put in, the electrical trenches are all dug, electricians dropped their conduit into the trench today, and were going to cover it tomorrow. Concrete decking getting poured tomorrow afternoon. Wife pushing the guys in a sprint to get the pool done.
I get to go to store and buy your recommended wire and conduit this evening. Thanks for the quick turnaround.
 
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Old 07-11-14, 05:29 PM
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Run 1-1/4 PVC conduit. Three #4's for your hot and neutral. I'm trying to determine if you can stay with the #10 ground or need to use #8.
 
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Old 07-11-14, 05:32 PM
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I get to go to store and buy your recommended wire and conduit this evening.
Why, I thought an electrician was doing this? I'm sure he would prefer to use the materials he feels are best not necessarily what you buy. When I was doing home repair I didn't want the customer buying the supplies because they invariably bought things I didn't want or were just plain wrong. Let the electrician supply what he needs. His cost will probably be less than BigBox.
 

Last edited by ray2047; 07-11-14 at 06:33 PM.
  #8  
Old 07-11-14, 05:43 PM
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Yes, that was the plan. Then the boss electriciansaid no way (today), too many permits to get. I was out of town, he spoke to my wife. He doesn't know I already got a permit for this work. He told my wife to have me do the work, use his trench. I'm just gonna get some supplies to have them here, and hopefully get his phone # or see him tomorrow. I have no desire to even drop conduit/wire in a trench. Reached a point where I'm happy to write a check to get it done right.
 
  #9  
Old 07-11-14, 06:29 PM
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He doesn't know I already got a permit for this work.
In my area a contractor cannot work under someone elses permit and must pull their own permit. All areas are different though, but it would be worth checking out.
 
  #10  
Old 07-11-14, 07:13 PM
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May be off topic:

The feed from the generator inlet in the shed to the main house panel may not carry utility power from the panel to the shed loads (receptacles and lights).

You may connect shed receptacles, etc. to that line but that line must remain connected to the transfer switch (or interlock) at the house panel receiving the generator power. That line can thus never be energized when the generator is not running.

You must install another feed between house panel and shed (shed subpanel) to power the shed with utility power. For the distance (150') I think you need #6 copper for 40 amps or #8 gauge for 30 amps.

This is something you need to plan while you have the trench still open.

The generator feed to the house is not a feed to the shed and therefore does not count as the one and only permitted feed from house to shed..
 
  #11  
Old 07-18-14, 01:29 PM
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Hi There - definitely 'on thread'.
After a fun last weekend of sweating over wire sizes, permits, labor, and time, this is what has happened:
I went to electrical supply store Monday 7AM and bought 220 feet of 1 1/4 PVC Schedule 40 Grey Conduit. (Big box guys over the weekend were useless and expensive.) I had glue. By 8am, was first guest at the town permit department for electrical. They were great. While there, my pool company called them to do the inspection of the dug trench / pool electrical work. They had pulled paperwork and knew I had a permit open to power the shed. The inspector said go put the conduit I needed, glued, in the trench, no wiring, and they'd inspect and approve while there for the pool electrical inspection. Said I could have the wiring done separately, for both power from panel to shed for lights and tools (Alan's note) and the power for the generator feed, at a later date. No hurry to pull wire/ get 2nd permit etc for my stuff. Nothing else, just take advantage of the open trench and put the conduit in there. By 9:15am, my son and I had glued 20 sticks and dropped them in the trench, capped the ends, marked the pipe clearly at the ends that it was my pipe and not the pool stuff, and I went to my full time job. Got a call at 11 from my wife that the town had been there, and inspected and approved both my work and the pool company work. The trench was backfilled with the soil, except for the very ends of the trench, by 1PM. By 3 PM, I'd contacted 3 electricians to provide quotes to do the work - which I meet with them tonight and tomorrow. Thanks again everyone.
 
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