100A sub panel to garage

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  #1  
Old 08-24-07, 08:02 PM
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100A sub panel to garage

Can someone tell me material-wise what is involved in adding a sub panel to the garage. I had an electrician upgrade my main service to 200A today and he gave me a bid for adding a 100A subpanel to my garage. His bid seemed a bit high. The job will require about 90 feet of wire, I already have the breaker box.
Thanks
 
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  #2  
Old 08-24-07, 08:43 PM
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Is the garage attached to your home or detached?

If detached do you want direct bury cable or conductors in conduit underground?

What is the panel rating in amps?...ie....how many amps do you want to feed the sub-panel if less than the max. rating or do you want to feed it the max. rating

What are you going to have as for loads (tools and equipment) ran from your sub panel??

Roger
 
  #3  
Old 08-25-07, 05:30 AM
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Sorry for leaving out so many details.
The garage is attached. I have no plans for a welder or any other high current use aside from the kitchen range which will be a maximum of a 20 foot run. I plan to run a circuit for a new 1/2 bath, one for garage receptacles, garage lights and that's about it.
 
  #4  
Old 08-25-07, 08:56 AM
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Much depends to the type of construction encountered when routing the Feeder cable or raceway between the Service and the SP--- exposed joists? finished walls & ceiling ?
A "straight" horizontal "run", or under a floor (horizontal) then up a wall ( vertical)


The type of constuction MAY require a "Raceway" ( PVC conduit), if a cable cannot be routed along exposed framing members- joists & studs.
 
  #5  
Old 08-25-07, 07:33 PM
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The basement (where the main panel is located) has suspended ceiling. I think the electrician plans to drill through some joists, then run it up through a wall that currently has no sheetrock (renovation in process) into the attic where the run will lie on top of ceiling trusses until it comes to the garage wall where it will come back down to the new sub panel. I don't believe there is any raceway involved. From my understanding, the job requires two 100A breakers (one at the main panel and another at the sub panel), the 00 wire (which he plans to use aluminum for) and the panel - which I already have.
 
  #6  
Old 08-26-07, 10:28 AM
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Do not use Aluminum conductors---- use 3/3 NM cable. You can estimate the lenth, and than price the cable to have an idea of the cost-of-material.

A "Main-breaker" at the sub-panel in not required.

IF ALL of the horizontal run is above a suspended ceiling,and is a "straight run", to avoid the labor of the electrician drilling joists, you can strap PVC conduit to the joists, and then pull the NM cable thru the PVC to where it extends vertically. You can also slip a 10-ft lenth over, say, 13ft of cable, strap the PVC to the joists, pull another 10 ft , slip on another lenth, etc.
The diameter of the NM cable determines the "Trade -size" ( ex : 1-1/4" ) of the PVC conduit.

The PVC conduit satisfies the "Protection from mechanical injury" Code-requirement, and is a very neat job.
 
  #7  
Old 08-27-07, 06:29 PM
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Originally Posted by PATTBAA View Post
Do not use Aluminum conductors---- use 3/3 NM cable. You can estimate the lenth, and than price the cable to have an idea of the cost-of-material.

A "Main-breaker" at the sub-panel in not required.

IF ALL of the horizontal run is above a suspended ceiling,and is a "straight run", to avoid the labor of the electrician drilling joists, you can strap PVC conduit to the joists, and then pull the NM cable thru the PVC to where it extends vertically. You can also slip a 10-ft lenth over, say, 13ft of cable, strap the PVC to the joists, pull another 10 ft , slip on another lenth, etc.
The diameter of the NM cable determines the "Trade -size" ( ex : 1-1/4" ) of the PVC conduit.

The PVC conduit satisfies the "Protection from mechanical injury" Code-requirement, and is a very neat job.
Whats wrong with aluminum used as a feeder?
 
  #8  
Old 08-28-07, 07:17 AM
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Originally Posted by Chris75 View Post
Whats wrong with aluminum used as a feeder?
---------------------------

A cable with three #00 Au conductors & an Equiptment Grounding Conductor is a much larger, and much more "stiff" cable than a 3/3 cable with copper conductors, and the 3/3 is much more flexible for bends, turns, etc.

Also, Au conductors are subject to corrosion at termination-points.
 
  #9  
Old 08-28-07, 05:50 PM
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I always find aluminum much easier to work with, if installed correctly I dont see corrosion as a problem...
 
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Old 08-29-07, 02:04 AM
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Au is the symbol for gold. Al is the symbol for aluminum.
 
  #11  
Old 08-29-07, 02:04 PM
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Au is the symbol for gold. Al is the symbol for aluminum.
And you thought Copper wire was expensive...
 
  #12  
Old 08-31-07, 07:03 PM
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I'm not sure if anyone has really explained to me what is involved in this project. Could someone tell me exactly what's involved? The main panel is in the basement of the East end of the house. The garage is attached on the West end of the house. Depending on how it's run, the length would be 80 to 95 feet. Is there any requirement for running a grounding rod near the box? I've not read that anywhere, but the guy at Lowes told me it was required.
As for the PVC, do I need any special type of fitting at the ends where the wire enters/ exits?
Thanks for any answers/ details
 
  #13  
Old 08-31-07, 07:42 PM
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You need to buy and read at least two books on home wiring, preferably three. The books will answer all your questions.

Do not rely solely on advice from any one source. Ask yoyur specific questions here after you read the books.

No, you do NOT need a ground rod, and adding one would be wrong. Your feed MUST be four wire.
 
  #14  
Old 09-01-07, 01:07 PM
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To answer your original question, wire size would be #3 CU or #1 AL. The ground rod question is a tricky one. It is required if you're installing a panel in a seperate building. Eventhough you have an attached garage, if it's on it's own foundation it could be considered a seperate building. If in question, I'd ask a local elec. inspector. Is there a way to get into the garage without going up into the attic and back down? This could save you up to 100' - 130' of wire ( 4 x 25' - 30'). You could also do some of the work yourself to save some money on labor. Any kind of set-up such as drilling holes, mounting sleeves, opening up the ceiling tiles where access is needed, and doing any clean-up should greatly save money. Talk to the electrician and see if he'll even let you run the cable from point A to point B for him before hand. Some will and some won't be OK with that because they're ultimately liable for the work done. Another suggestion is to shop around. Just make sure that cheaper estimates aren't at the expense of quality.
 
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