Commercial Branch Circuits - Designing

[jimmi]

Hello All, I'm in a little over my head, as our firm is "normally" a data/comm contractor.

Anyway, we've been asked to provide additional outlets in classroom next to the data jacks.

So here's my question/problem.
Each classroom will have 2 quad outlets, each quad will have 2 circuits.

When I run netural sharing circuits, what size is the netural (20 Amp)? Next, do I only need 1 ground in the conduit regardless if the number of circuits? What size should the ground be? Our furthest conduit run from a panel is approximately 155'

Finally, how do I figure the conduit size based on the number of conductors/circuits?

The system is 120/208 3 phase

[ March 27, 2004, 11:25 AM: Message edited by: jimmi ]

 

[iwire]

Re: Commercial Branch Circuits - Designing

There are many answers to that question.

[ March 27, 2004, 11:46 AM: Message edited by: iwire ]

 

[jgriffin]

Re: Commercial Branch Circuits - Designing

IWIRE,....EVER notice how electrical apprentices can post these same questions and we ALL want to help?

 

[bill addiss]

Re: Commercial Branch Circuits - Designing

jimmi,

Are you asking for help preparing an estimate?

I'm assuming that you are and that someone in your company does know how to do this work. Based on that assumption I would recommend that you get together with them over the plans to make sure that there are no other factors (such as derating) that you may be overlooking.

Bill

[ March 27, 2004, 12:50 PM: Message edited by: bill addiss ]

 

[jimmi]

Re: Commercial Branch Circuits - Designing

Thanks, for all the replies so far.

I am not asking for help for the actual estimate. I am asking for help to design the branch circuits. However, I don't do this regularly, so I am a bit of a loss. Most runs we do are onesy twosey so throwing a peice of 3/4 in with a few THHN's is no biggie.

I know the project has potential flaws, but I need to win the project to make suggestions for improvement. Currently none of the switchgear has any surge suppression means, and IMO that's needs addressed.

Yes, we do have an electrician on staff, but he is unavailable for the next week, so I was hoping to get some help to figure this out for myself. (I need to learn it anyway).

 

[bill addiss]

Re: Commercial Branch Circuits - Designing

I am asking for help to design the branch circuits.

Here's where I saw a potential problem.

I don't mean to sound Cold, but generally if someone is not aware of applicable codes and factors that might affect design decisions they don't know what questions to ask.

I think your best bet would still be to get someone to go over the plans with you one-on-one, and they might even be able to point out shortcuts or ways to simplify the installation that could lower your Bid.

Bill