Do I need a subpanel? Should I "double up"?


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Old 05-14-09, 06:38 PM
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Do I need a subpanel? Should I "double up"?

I hope someone can give me some advice about this. I'll try to keep it brief.

I'm doing a basement remodel. All the slots in my main (and only) panel are filled. There are 3 items (a/c, range, dryer) that take up two slots. Mostly the rest are 15 or 20amp breakers with two switches on them (bear with me, I'm just a homeowner :-)

My builder, who's not an electrician but knows a thing or two, thought it was obvious that I'd need a subpanel to have proper coverage in the basement (which is now all on one circuit, including a bathroom, and in future will have a range outlet). This is a pretty old house and most of the wiring is pretty old.

I've gotten 3 bids from electricians. One of them, the guy I "liked" the best, and seemed trustworthy and was _cheapest_ (and youngest ) said that we wouldn't need a subpanel, but he could "double up" a bunch of stuff to make room in my current panel. I believe he's fully licensed, etc, but haven't checked him out.

I realize you can't see the situation yourselves, but... does this sound right? Should I not hire the guy who wants to "double up"? Should I go with one of the more expensive guys who seem to think the subpanel is needed? Is it possible this younger guy will be breaking code by doing this?

Thanks!
Dave
 
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Old 05-14-09, 07:49 PM
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Doubling up some circuits could lead to breakers tripping from being overloaded.

Tandem breakers might be an option, but we wold need to know the panel model to see if that is an option.

I think the subpanel is probably your best bet.

You may want to have a demand load calculation done to see if your service size is large enough for the added loads.
 
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Old 05-14-09, 08:19 PM
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Thanks for the response. Here's what I can figure out:

The panel is a Square-D Homeline Load Center Series S01 Type 1 enclosure. It has 12 (what I'm calling) slots.

I had my service upgraded when we moved in, several years ago. If I recall correctly, it was raised to 125 amp.

The house is about 2700 sqft, including the basement. I don't have any unusual electricity requirements, although as I mentioned there will be two oven-ranges, one on each floor (and a fridge in the basement too).

Thanks again.
 
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Old 05-14-09, 10:11 PM
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I agree that a subpanel is probably the best option for you. A twelve space panel (perhaps even 24 if tandems are allowed) is simply not enough circuits for a 2700 sq ft home with finished basement and two kitchens.

The proposed basement alone will require at least 7 circuits to be compliant (2 range, 2 SABC, 1 bath, 1 smokes/lights, at least 1 general-purpose).

My gut feeling is that 125A is teetering on the edge of adequate for your service size. A formal demand load calculation should probably be done to determine if you just need a subpanel for more space or if you'll also need more capacity making a 200A 40 space panel the correct choice.
 
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Old 05-14-09, 10:16 PM
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Right now your exsting service is pretty much on the borderline with current setup but once you add second range or other powerfull stuff like spa { belive me some day you will add down the road if the situation is right } then you will have to bump up to 200amp service and with 2700 sqft that pretty much smack right in 200 amp size.

Merci,Marc
 
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Old 05-15-09, 11:38 AM
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I advise the SP ; you may need to connect more circuits in the future. Also , you can connect fewer outlets-per-circuit because the space for extra circuits is available. There also may be the problem of un-sufficient conductor terminals in the existing panel for the adiditional Neutral and Grounding conductors.
 
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Old 05-15-09, 09:22 PM
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Thank you everyone for the useful responses. I have one more question.

I don't want to upgrade my service to 200A now, but if I get a subpanel put in that is large enough to accomodate 200A with plenty of places, will that be a good? My main panel right now is in a somewhat inconvenient location, so can I depend on the subpanel to take up all the slack I might need? Or is there some reason why service upgrade would require an upgrade to my MAIN panel? I guess what I'm saying is: Is it ok for the subpanel to be "bigger" than the main panel? Sorry if that sounds naive, but IANAE

Thanks,
Dave
 
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Old 05-15-09, 10:13 PM
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If you add a 100a sub panel and need to later upgrade your service you could have a double lug 200a meter can installed. The subpanel would be converted to a second main panel with the 200amp split between the two panels. The original would have to be lowered to 100a breaker if indeed it is 125a but between the two you would have 200 amps.
 
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Old 05-16-09, 02:51 AM
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Why are you trying to cut corners with the electrical? Wouldnt you say thats the most important aspect of this project? Could faulty plumbing burn your house down?

Lets say he "doubles up" which I imagine means placing 2 hots on 1 breaker (your original post leads me to believe you already are using tandem breakers since you said your breakers take up 1 slot with 2 switches) - now you have twice the load on a single circuit, dedicated devices are no longer dedicated and you've increased the risk of over-current. You will put those breakers to a test and god forbid one doesnt trip because fire will result.

It sounds like you will need to upgrade your electrical - with a larger panel or subpanel at a minimum. Perhaps you are not ready for this remodel if you are not willing to do it correctly in all aspects
 
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Old 05-16-09, 11:50 AM
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If the new SP and the existing Service-panel will be "side X side ", meaning 3-4 inches of space between the two panels, you could select a SP with a 200 amp Main Breaker and X number of circuits.

Next is the ampacity of the "Feeder" conductors between the old / new panels , best done with 100 amps conductors protected by by a 2-pole, 100 CB in the existing Service panel.

In the new sub-panel , The 100 amp Feeder conductors terminate on the lugs of the 200 Main CB. When you Up-grade , the new 200 amp Service conductors terminate of the lugs of the 200 amp Main CB , and the 100 amp conductors are transferred from the "Main" 200 amp lugs to a 100 CB in the "new" Service panel. The "old" Service panel is now a sub-panel.
 
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Old 05-16-09, 12:08 PM
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For now if it was myself I would add a sub panel for now. If you have the money then think about putting in a 200 panel with 40 spaces and you'll be good for as long as you live in your home. Don't double down with the breakers.
Thanks!

JimBeer 4U2
 
 

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