In this question, I asked about problems between my circuit breaker for a circuit shared by my microwave and sump pump. The conclusion was that another circuit should be added to support the microwave on its own. I have open spots for breakers in the box. Assuming I have an electrician do this job, how much should I expect it to cost? If location is a variable, I'm in central Maryland.

Note that the new circuit could be added to support only the sump-pump in an unfinished basement. So my thinking is that it should be one of the easiest additions possible.

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    You might want to mention where you are (contractor prices can vary considerably). In my area (suburbs of Philadelphia, PA), I figure on $60 - $75 for anyone to just show up. The actual work is on top of that figure. Aug 16, 2010 at 2:06
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    That's precisely why my first paragraph ends with I'm in central Maryland. Aug 16, 2010 at 2:24

3 Answers 3


It is fairly simple to add an additional breaker to a box but of course there would be some sort of minimum charge to come out and also the cost of the breaker, so probably around $100.

BUT that assumes the actual line for the sump pump/microwave (the one you want to put on the new circuit) is all by itself. I have seen some interesting wiring in old houses where one thing is wired to the next which is wired to the next and eventually all of it goes back to the same breaker. The electrician might need some time to figure out how the microwave and/or sump pump are currently wired before being able to propose a solution. If this is the case then I would expect a much higher bill (since this is no longer a trivial "install a new breaker" job).

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    Wiring from one outlet to another is common in both old and new construction. Aug 16, 2010 at 15:59
  • Thanks for providing some numbers and reasoning. I guess I won't really know for sure until I get someone out for it, but this helps me know what to expect! Aug 17, 2010 at 4:35

The only way to get an accurate figure for your area is to call a bunch of electricians near you, and they won't be able to give you a really accurate number without seeing it. They should be able to give you a range, though.

The sump pump should be on its own 20A circuit without a GFCI. (GFCI may now be required by NEC 2008 edition. Will update when I know for sure.)

The lights and outlets can stay on the same circuit if the outlets have GFCI protection. They're probably going to want to move the microwave to a different circuit while they're at it- unrelated locations really shouldn't share a common circuit.

If they are making any modifications to a circuit that has anything not allowed by the current electrical code (which it does), they will have to make it all correct.

  • why should the sump not use a GFCI? In my case, the sump was plugged into a basement circuit wired from metal conduit, and the inspector made us use a GFCI since it was in the basement.
    – mohlsen
    Aug 20, 2010 at 21:29
  • @mohlsen : ever had a GFCI circuit seemingly randomly trip on you? Now imagine that you haven't had to run the pump in 10 months, and you're asleep or away at work when the rains come ... if the circuit was tripped, no sump, and flooded basement.
    – Joe
    Aug 22, 2010 at 13:09
  • Yes- GFCI breakers used to be recommended (required?) for sump pump installs, but because of the risk of flooding, the NEC now states specifically that sump pumps should not be GFCI-protected. They decided that a flooded basement is more likely to get somebody electrocuted than a sump pump without a GFCI. Just don't go swimming in the basement! mohlsen, I would check regularly to make sure the interrupter hasn't tripped. If it is having false trips, I would call up your inspector and ask if you can change it out.
    – nstenz
    Aug 22, 2010 at 16:58
  • makes complete sense. I am going to change it out to be a standard plug.
    – mohlsen
    Aug 23, 2010 at 23:42
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    I may be incorrect. The NEC 2008 edition now applies in my jurisdiction, and one of the books I'm reading says that all unfinished basement receptacles must have GFCI protection, without exception (2008 code change). I'm going to try to find the section in the actual NEC, which can be read for free if you sign up at nfpa.org (but there's no search or printing). So it definitely depends on your local regulations.
    – nstenz
    Aug 25, 2010 at 2:00

Parts are cheap

$5 for the breaker ($9 if Square D QO, $50-ish if an obsolete panel like Pushmastic, FPE, Zinsco etc.)

$15-ish for the electrical wire.

???? for the labor.

The labor will vary wildly by the practical difficulty of routing the cable, and will depend on things like the total distance, level of finished-ness in the route areas (finished vs unfinished basement), whether the last guy left you some conduit to use, stuff like that.

That variability is precisely why costing questions are a bad fit for this stack.

Off-load the other loads

Depending on your physical access, it may be better to leave the microwave on this circuit, and move everything else to an alternate circuit. Last I looked, basement outlets and sump pumps tend to be in basements, and basements tend to be unimproved (or under-improved) and easier to install wiring (certainly no harder). So the better plan may be to move the sump pump and/or basement receptacles onto separate circuits.

Leave the basement lighting on the microwave circuit; these days lighting is a very small load, and it's nice to have the basement lights Not go dark when you trip the breaker from running tools.

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