1

We are looking to install a hot tub and trying to find out if our service panel will accommodate a 240v circuit breaker.

This is what our panel says but I do not know what all of this means:

CAT NO

SC1624M100C

RAINPROOF TYPE 3R ENCLOSURE

MAINS 125 AMP. MAX.

SEE SERVICE DISCONNECT FOR RATING

120V/240V. AC. 1PH. 3W

METER SOCKET RATED 200 AMP CONTINUOUS

MAX. BRANCH BREAKER - 100 AMP

Please help me understand if I will need a service change (like $2500) or just able to add a 240v Circuit breaker in the panel that would be much less expensive.

  • 3
    Are there any free spaces in the panel (you'll need two next to each other)? – Tester101 Jul 11 '14 at 17:41
  • 1
    A photo of the panel, with the door open would be helpful. – Tester101 Jul 11 '14 at 17:41
5

The panel can indeed support a 240V breaker. The question you should ask is, is there space in the panel to physically accommodate additional breakers?

Based on the model number, your panel should look something like this.

enter image description here

Notice how this example image has lots of blank spaces. In a panel like this, there's no problem at all installing a new breaker (or double pole breaker in your case). However, it's not likely your panel looks like this. More probable, is your panel has all or nearly all the slots full.

If there are not two free spaces in the panel, you'll not be able to install a new breaker in this panel. You have a few options in this case.

  • Install tandem breakers where possible to free up slots.
  • Install a subpanel.

The other problem you could have, is that your current service will not handle the additional load. This panel can handle 100 amperes, but that does not mean you have 100 amp service. You'll have to check with the local utility to determine the size of the current service. If

Lastly, the panel might already be close to being overloaded. If you have all electric appliances (Range, Dryer, heat, water heater, etc.), adding a hot tub could cause the main breaker to trip from time to time. This will completely depend on your current consumption of power, which is not possible to know based on the information you've provided.

tl;dr

Contact a local licensed Electrician to determine what's required with installing a hot tub.

  • tldr's go at the top. – Chris Cudmore Jul 11 '14 at 18:56
  • 1
    @ChrisCudmore tl;dr's go at the bottom, so you have to read through the whole post to get to it. – Tester101 Jul 11 '14 at 19:00
  • sort of defeats the purpose then. – Chris Cudmore Jul 11 '14 at 19:09
  • I have only seen tl;dr's at the bottom of posts. Then I found this: meta.stackexchange.com/questions/137120/… One more thing that is weird about this site(s). – Speedy Petey Jul 12 '14 at 0:14
  • @ChrisCudmore that's sort of the point. It's humorous to me, that a user has to read all the way through to get to the "too long; didn't read" section. – Tester101 Jul 12 '14 at 1:55
4

TL;DR: Yes, your panel should accommodate the breaker, provided you have space.

Quick lesson in North American circuitry. The supply to your house is 240 v, split phase. This means that there are 3 wires coming in. One is 120v, one is grounded, and one is 120 v, out of phase with the first.

If we switch our thinking to DC, you could (incorrectly) think of it as +120v, 0v, and -120v.

So a normal household circuit runs from one of the two phase wires, to the grounded conductor (neutral) and gives you 120 v.

If you were to run a circuit, not from Phase 1 to neutral but from phase 1 to phase 2, you get 240 volts.

Now we get into the design of a panel. The panel is designed so that adjacent breaker slots are on different phases. So a 240 v breaker takes advantage of that. It's twice as wide as a 120 v breaker, and takes up two adjacent slots.

See this for pretty pictures. (9 page slide show.) http://homerepair.about.com/od/electricalrepair/ss/anat_elec_pnl.htm

See: http://en.wikipedia.org/wiki/Split-phase_electric_power for a more rigorous description.

  • Great! Thank you for your help. The panel does have 3 adjacent slots at the top without switches. – Kelly Jul 11 '14 at 17:49
  • Get an electrician to do it. – Chris Cudmore Jul 11 '14 at 17:53
  • Yeah, I have called one but wanted to find out ahead of time if I would be looking at a service change or not. – Kelly Jul 11 '14 at 17:57
  • Also, keep in mind that although it might physically fit in your panel, you could still electrically overload it. – Chris Cudmore Jul 11 '14 at 19:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.