Close or far sub-panel location?

redownsFebruary 6, 2014

I'm getting ready to start wiring for my basement addition. I've already decided to install a 100amp sub-panel along with 6-8 circuits. The distance from my service panel to the primary area where most of the circuits will be located is between 40-60'. My first thought was to locate the sub-panel closer to most of the circuits, therefore requiring a single long run (with steel conduit) for the 4, low-gauge individual feeder wires, allowing for much shorter home runs.

My other option is to locate the sub-panel close to the service panel (much short feeder wires/cable), but much longer multiple home runs (basically most would be 30+ feet.) Which option is the most cost effective? I'm guessing the elimination of steel conduit and 4, #3 gauge wire will save more than the added cost of multiple, longer home runs ROMEX cabling. Is there any conventional-wisdom on this from local electricians?

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bus_driver

Often one of the reasons for using a subpanel is to minimize the length of runs of NM cable and to bring the circuit breakers nearer to the point of use to simplify shutting off or resetting of the breakers.

    Bookmark   February 6, 2014 at 7:26PM
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jreagan_gw

I have a 100A subpanel in my garage that is at least 40' away feed exactly as you think with steel conduit and sufficient conductors.

    Bookmark   February 7, 2014 at 8:26AM
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redowns

So it's more convenient to have access to both boxes - perhaps next to each other - and longer home runs? That seems like a very rational and sound reason. I'm not sure I have enough room to install a sub-panel right next to my service panel, but I can get it very close by - thus minimizing the amount of feeder wires and steel conduit. I'll have to double-check my location of service panel and see where space may be available for the sub-panel.

Thanks for the reply. -redjr

This post was edited by redowns on Fri, Feb 7, 14 at 9:41

    Bookmark   February 7, 2014 at 8:32AM
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Ron Natalie

In my old house I had one sub panel next to the panel (mostly done to get enough spaces to put sub panel feeders in) and another in the garage-turned-workshop.

In my new house I have no "main panel" really. There's a gigantic 400A disconnect switch on the utility ahead of the ATS for the generator. Then there's a "main" sub panel and several satellite "subpanels" around the house.

    Bookmark   February 7, 2014 at 9:43AM
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greg_2010

So it's more convenient to have access to both boxes - perhaps next to each other - and longer home runs?

Actually, I think they were saying the opposite. It's more convenient to have the subpanel closer to where the circuits are actually used.

    Bookmark   February 7, 2014 at 11:22AM
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jreagan_gw

Yes, I have two 200A panels in my basement at each end of the house. One is for the living areas and HVAC; the other is kitchen/laundry area. One of those in turn feeds a 100A panel in my garage.

    Bookmark   February 7, 2014 at 12:35PM
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redowns

You are correct. I went back and re-read the reply. Thanks for clearing that up for me. I am loosing my mind! :(
Edit.. Is there any point in discussing the cost of each?

This post was edited by redowns on Fri, Feb 7, 14 at 14:24

    Bookmark   February 7, 2014 at 2:23PM
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worthy

It's much likely to be cheaper to keep the sub-panel close to the main panel than near the service locations. But it can be very inconvenient.

For example, in a spec home I built with a separate basement apartment, I ran Teck armoured cable to a subpanel in the basement. It's not easy stuff to work with when you have to twist and turn it behind framing.

    Bookmark   February 8, 2014 at 8:09PM
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petey_racer

My question is WHY are you wanting to run metal conduit in a basement???

    Bookmark   February 9, 2014 at 8:31AM
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Ron Natalie

I don't know why you think it would be cheaper (even in Canada). One big cable is likely to be cheaper than tons of small ones both in labo(u)r and the fact that there's going to be excess copper involved (the ampacity of the feeder is less than the aggregate ampacities of the branch circuits in the sub panel).

    Bookmark   February 9, 2014 at 12:30PM
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redowns

"My question is WHY are you wanting to run metal conduit in a basement???"

I'm never said I wanted to run conduit. I'm asking for the better/convenient option - which may include conduit. As I understand Connecticut code when you are using single #2/3 gauge wires they must be encased in steel conduit.

The essence of my question is.. if I locate the sub-panel closer to the circuits than I have to run either the very thick #2, or #3 gauge, 4-conductor cable to the sub, or install conduit and run 4 individual wires which are much easier to work with. No? This is my first time installing a sub-panel hence my question.

If I install the sub inches from the main panel all of this is moot, but then I have to run more 15 and 20 amp home runs for each circuit. Right? Am I not making myself clear?

This post was edited by redowns on Sun, Feb 9, 14 at 17:17

    Bookmark   February 9, 2014 at 5:04PM
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redowns

"I ran Teck armoured cable to a subpanel in the basement. It's not easy stuff to work with when you have to twist and turn it behind framing."

Can you be more specific about the Teck cable? What gauge/amp rating was it and I'm assuming it was 4-conductor. LInk? Since I'm installing a 100-amp service panel as my sub-panel (for more circuits), does not the feeder cable need to support at least 99.9 amps steady current without melting or tripping the breaker? Not that it would ever pull that much continuous current.

    Bookmark   February 9, 2014 at 5:26PM
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petey_racer

"I'm never said I wanted to run conduit."

You kinda did. Twice.

Putting the sub-panel closer to the loads (as opposed to next to the main) is a big benefit, on several levels. This is what has been said several times in this thread.

You can feed the sub with whatever feeder you want, but at least 30A. The panel size almost does not matter. It's the calculated (or actual) load that matters.

    Bookmark   February 9, 2014 at 10:05PM
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greg_2010

Be aware that when you are figuring out the size of the sub panel that you need, you don't add up all of the amps of the circuits you are going to install to come up with the size.

If you are only going to have 6-8 circuits in your sub panel, a 100a feeder seems excessive. Especially if those circuits are just 15a 120v circuits.

So you'll have to figure out the proper size of the sub panel before you start doing a cost comparison.

(Edited to say: Never mind, I just saw that you started another thread to discuss this issue)

This post was edited by greg_2010 on Mon, Feb 10, 14 at 9:51

    Bookmark   February 10, 2014 at 9:48AM
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jreagan_gw

Well, I have metal conduit in my basement. Personal choice I guess.

    Bookmark   February 10, 2014 at 4:08PM
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rwiegand

I forgot to ask for a disconnect on the subpanel in my barn, so now I have to trudge back to the house and into the basement (uphill both ways, and in the snow) whenever I want to kill the power to the subpanel to do any work on it.

    Bookmark   February 11, 2014 at 1:01PM
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