# Residential to Commercial electrician



## besc (May 16, 2010)

Been resi up to now. First commercial. My thoughts, then, yours, please.
This is a trucking company and will be trenching driveway and parking lot.

Install 400 amp 3ph outdoor service with 2 operations of 200 amps each.

One of the operations will feed a building 120ft away at 200 amps 3ph to sub panel.

Here's the plan
Trench driveway 18 inches for 3in schedule 40 pvc.
Run Southwire 4/0 4/0 4/0 2/0 in conduit.

Your input. My first commercial job. I'm in California. Thanks. Mike.


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## telsa (May 22, 2015)

besc said:


> Been resi up to now. First commercial. My thoughts, then, yours, please.
> This is a trucking company and will be trenching driveway and parking lot.
> 
> Install 400 amp 3ph outdoor Service with* 2 feeders *of 200 amps each running off to* 2 panels.*
> ...


1) Your GEC System scheme has to be perfect. You'd best own and read a NEC Handbook. Ground rods... :no::no::no:

2) In commercial parlance there is no such thing as a sub-panel. They are all "panels."

3) You can't reduce your neutral conductor one iota. That's strictly residential thinking.

4) You MUST bring a bonding (Green) conductor along -- up sizing it if the hots were up sized -- which is the case here.

5) 18" will NEVER 'cut it' under a driveway. 

6) Bedding material is standard procedure. Stay with sand around the pipe. You won't regret it. The upper layers must be 'stone-free.' And compacted in layers. Moist sand compacts the quickest -- just walking on it is sufficient.

7) Wet cut the asphalt. Shovel off the base (A&B) -- or hire out to a decent back-hoe operator who knows the ditching game well.

Watch out for crossing trenches you don't suspect. Again, another reason to hire out the ditching.

8) The back-hoe can ditch out your Ufer at lightning speed, too. You'll regret using a chain trencher, if you try it.


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## Julius793 (Nov 29, 2011)

telsa said:


> 1)
> 
> 3) You can't reduce your neutral conductor one iota. That's strictly residential thinking.


I do not believe you are correct. There are times you cannot reduce the ungrounded conductor but it's not based upon resi/commercial


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## telsa (May 22, 2015)

Julius793 said:


> I do not believe you are correct. There are times you cannot reduce the ungrounded conductor but it's not based upon resi/commercial


Clean this up.

Unable to parse.


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## besc (May 16, 2010)

Ugh. Sorry. But what's a Ufer.


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## telsa (May 22, 2015)

besc said:


> Ugh. Sorry. But what's a Ufer.


Google is your friend.

http://www.ecmag.com/section/codes-standards/what-ufer-ground










*You REALLY need to purchase the NEC Handbook.* :thumbsup:

Not the NEC Codebook. :no:

If you can't afford it, you're out of business. :laughing:


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## Speedy Petey (Jan 10, 2007)

besc said:


> Ugh. Sorry. But what's a Ufer.


CEE, or concrete encased electrode.


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## telsa (May 22, 2015)

Unless the client insists, you're best advised to skip the copper and pull aluminum feeders.

1) Much easier on the tugger.

2) Much cheaper on the wallet.

3) Easily fit inside 3" PVC.

350 kCMIL I should think.


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## telsa (May 22, 2015)

Heads up: in California you're not going to get away with undersizing your neutral feeder to a lighting and general use panel board.

The OP specified "trucking company."

No way is this a motor control center.

The OP scheme was based upon the norms for _*dwellings.
*_
Out here, ground rods are categorically rejected by the AHJ, even for homes.

The OP did not bring up any of the details of the Service, which, out here, would be expected to be a service lateral. Over head drops are commonly prohibited by zoning.

Any way you figure it, the OP needs to have a veteran journeyman on his crew who has jumped through these ropes before. 

Califoria is EUSERC land. So plenty of the ideas from the East Coast won't fly here.

BTW, the OP had better be sure that his Service equipment is EUSERC qualified. Most offerings are NOT.

The OP did not mention whether this project is an add-on to an existing Service -- such that he's only really worried about the one feeder.


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## Signal1 (Feb 10, 2016)

> You REALLY need to purchase the NEC Handbook.


Yup



> Any way you figure it, the OP needs to have a veteran journeyman on his crew who has jumped through these ropes before.


Yup



> Trench driveway 18 inches


That said it right there-


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## besc (May 16, 2010)

Its a feeding frenzy. Anyone else care to slime in?


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## Majewski (Jan 8, 2016)

Slimer?

Agree or not, tesla is giving you correct info. He's kind of a smart mofo.


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## besc (May 16, 2010)

I was referring to signal1. That wasn't necessary. As said, my first commercial job. I guess his insides got the best of him.


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## MechanicalDVR (Dec 29, 2007)

besc said:


> Its a feeding frenzy. Anyone else care to slime in?


Being new to something isn't a condemnation. You asked the question so you need to know the correct answers. Take the benefit of Tesla's knowledge to your advantage. Nobody here is looking to scold you as much as assist you in doing it all by the book and not learning through the prize of a red tag.


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## besc (May 16, 2010)

As stated above I was not referring to Tesla but Signal1


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## Signal1 (Feb 10, 2016)

besc said:


> I was referring to signal1. That wasn't necessary. As said, my first commercial job. I guess his insides got the best of him.


And I was agreeing with Telsa. He's right.

Your OP has a thousand dollar mistake just on your trench alone. You want to lay that conduit twice?

If you only do resi you need help on this one. Nothing wrong with that. I help other electricians with commercial fire alarm systems all the time.

This has the potential to cost you a lot of money.


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## telsa (May 22, 2015)

The OP had best dial in on the Service, too.

If he's going to be setting a new one.

There is MUCH to trip him up.

The OP did not specify if the Service was 480Y277 or 208Y120. 

I assumed the latter.

If 480Y277 he'll need to set both high and low boards... with SDS to feed the low boards.

I'm open to a PM. 

BTW, as a First Commercial Job, this is a huge jump. Most residential C-10s start with trivial tenant improvement projects.

Most residential C-10s are stunned as to how different the rules of the game are.

This cuts the other way, as most Commercial C-10s lose their a$$ touching residential.


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## besc (May 16, 2010)

Hay guys. I had a bad weekend and not related to electrical. I did a little venting there that wasn't necessary and Monday is a day of reflection. You guys are all a big help and I appreciated all the info. By the way, the 18 inches was a typo. I meant to say 36 so that it would be 30 from the top of the conduit. This is a big jump from resi but an exciting one. So I think. (Be careful what you wish for.) I am going to get my bearings and continue with this and looking forward to your experienced info. Thanks. Mike.


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## Majewski (Jan 8, 2016)

Hey man, we all have ups and downs! Maybe it's a Mike thing?! Lol


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