Is an increased electrical service worth the extra cost?
September 15, 2012 1:46 PM   Subscribe

Is upgrading an electrical service worth the extra expense?

I'm having my service panel upgraded and am currently reviewing the quotes from the electricians. One of them quoted me for a) replacing my existing 100amp panel with a new larger panel and b) upgrading my service from 100amp to 125amp and replacing the panel with a new larger panel. He is the only one who offered this as an option. One of them leaned towards simply upgrading the 100amp panel, and the other leaned towards installing a sub panel.

The house is about 1700 square feet, has air conditioning, and uses gas for heating and hot water. The stove and dryer are electric. We would like to put a hot tub in the back yard in a few years as well. The existing panel was installed in 1971 and has no empty slots. We are also finishing the basement and will be adding additional circuits to the overall system.

Would there be any value in upgrading to the 125amp service or should we save the extra expense for other finishings? The difference in price is about $800 since the electric company has to cut power at the transformer and a new meter base would need to be installed.
posted by smcniven to Home & Garden (6 answers total) 2 users marked this as a favorite
you could perhaps attempt to calculate a current rough ampere usage. If it does not exceed the capacity of your current service and equipment, I would save the money.

Unless you are in a position to save money by doing the work now (the home is under construction, etc) or your lights are dimming when large power drains in your home activate, I can not think of a good reason to plunk down nearly a grand if it does not offer direct benefit.
posted by fieldcannotbeblank at 1:49 PM on September 15, 2012

I have 100A and didn't bother upgrading service when I upgraded the panel. While I don't have a hot tub, you have to really put some effort in to require 220A. (Note that I also have a gas dryer.) I think it's overkill and wouldn't bother.
posted by zvs at 2:06 PM on September 15, 2012

FWIW the hot tubs I see online require 30-50 A for a hardwired 220 V connection. So you would want that in addition to your load calculation.
posted by Monday, stony Monday at 2:15 PM on September 15, 2012

Best answer: "Would there be any value in upgrading to the 125amp service or should we save the extra expense for other finishings? The difference in price is about $800 since the electric company has to cut power at the transformer and a new meter base would need to be installed."

I did a house calculation (this is how code tells electricians minimum size of service) using the following criteria:
  • 1700 square feet of living space not including basement. If you included the basement the final figure changes very little.
  • Gas heat with no electric heating sources like heated tiles in the bathroom or a baseboard in a mud room.
  • Gas hot water.
  • 5000W for A/C
  • 4000W for Hot Tub
  • 5000W for Dryer
  • and 6000W for your range (code specifies 6000W for any range up to 12000 Watts).
The values I chose for appliances where you didn't supply wattage numbers for are the defaults I use. Another electrician will undoubtedly use different numbers but generally those numbers are good for unknowns give or take a 1000W.

I get a minimum service ampacity of 108.3A using my defaults. Legally (in BC anyways, your province might be different) an electrician isn't required to accommodate future draws in a house calculation so they could get away with specing a 100A service by dropping the hot tub or choosing different values for the amp draw of the A/C and Dryer (and it's entirely possible that the plate values of the draw of those two things are less than I guessed.

However I believe that not including the hot tub in the calculation would be a disservice to a customer who has a clear intention to add one in the near future. And even lowering the guesstimated wattages by a 1000W each only drops the calculated draw to 96A; a lot closer to the 100A limit of a main breaker than I like to get.

So if it was me I'd strongly suggest to my customer to go with more than a 100A service. In fact I'd recommend going straight to 200A in most cases because the difference in price is essentially only the increased cost of the wire from the mast head to the panel as the labour, hydro charges, and, practically speaking, panel cost are the same but it allows for future growth like say a detached workshop, a suite, or an electric car charging station.

The only real drawback is the 200A panel must be a minimum of 40 circuits which is physically larger than the 24 and 30 circuit minimums at 100A and 125A respectfully. However, IMO, the code minimum sizes are woefully inadequate for smaller panels considering all the special breakers and circuits required in a modern house (AFCIs, GFI and individual circuits for fridges, exterior plugs, deck plugs, and only two plugs per kitchen circuit etc.) so the larger panel is actually desirable in it's own right.

TL;DR: Go with the 125A and consider 200A.

PS: the sub panel is a cheap way of getting more circuits but doesn't get you any more power.
posted by Mitheral at 6:58 PM on September 15, 2012 [2 favorites]

We just upgraded a house from 100 amp to 200 amp, but the power drop from our provider was already adequate for this. It cost us about 2000 extra, since we have an external shop, electric hot water, dryer and wanted electric wall heaters upstairs (since we were on plug in heaters for that). PLan ahead and eat the extra cost. It is worth it and makes the house easier to sell (not necessarily more valuable since most buyers expect 200 amp service as standard now). It also makes the house a lot safer for things like, you know fires. An overloaded service panel can be dangerous (although modern safety features are pretty damn good). and spending a little extra now can save a whole other install at full price later-go with 200 amps.
posted by bartonlong at 8:16 PM on September 15, 2012

Response by poster: Thanks Mitheral. I'm leaning towards the 125amp upgrade. Unfortunately going to 200amp would cost a small fortune since all our neighbourhood has underground wiring. It would be at least 30-40 feet to the transformer.
posted by smcniven at 8:54 PM on September 15, 2012

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