Home Electricity
New Electrical Work
Modification of Old Electrical Work

What is involved in installing a new 240V breaker in the main breaker box so you can add a 240V receptacle?


Top Answer
User Avatar
Wiki User
2012-11-03 12:52:17
2012-11-03 12:52:17
for USA, Canada and other countries running a 60 Hz supply service.You are going to need a number of things:

* A 240V double-pole breaker of the right size for your load, (Don't try and use two single-pole 120V breakers!) and the right type for your box (SquareD breakers for SquareD boxes, GE for GE, etc.)

* A length of 4 conductor wire to run from the breaker panel to the outlet that is the right size for the breaker! Rule of thumb for wire runs under 50ft: 14 gauge for 15A, 12 gauge for 20A, 10 gauge for 30A, 8 gauge for 40A, 6 gauge for 50A, etc. Get 4 conductor wire even if you only want 240 (and not 120) for futureproofing.

* A new outlet and box to mount it in.

* Clamps to secure the wire to the box and breaker panel.

Then you need to:

* run the wire from the panel to the outlet. Leave slack at the panel, you need a couple feet inside it.

* Wire the 240V outlet. Remember the color code: the black/red/brass screws are for the black and red hot wires, the white/silver screw is for the white neutral, the bare/green screw is for the bare or green-covered ground wire.

* One slip and you're dead. So always shut the breaker panel main switch to OFF.

* Connect the wires into the panel. Which bus is which should be obvious by the existing wiring. Remember to get your connections good and tight.

* Put the covers back on everything, switch everything on and enjoy.

If anything I said above wasn't obvious, buy a book. It will explain everything better than I can in text and serve as a handy reference on the job. If you are still not confident, hire a professional licensed electrician.

Negligence with electricity is fatal.


Some things to remember are:

A - You must kill the whole box before jumping in it. KILL IT.

B - never grab more than one wire - or contact - at a time!

C - Try not to ground yourself out.

D - always use the right size wire for amperage needed.

E - You do not have to be a brain surgeon to wire in a circuit. If you are not totally confident with what you are doing definitely consult someone who will be nice enough to give you life saving tips instead of telling you to take a hike.


As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.





Related Questions

if i have a breaker that has a 120/240v and my dryer has a 240v plug can i change the receptacle to a 240v

A 100 amp breaker is too large for the average range. If you meant 100 amp service panel then the following installation will work. The most common size breaker used in North America for an electric range is a two pole 40 amp breaker. The feeder to the range receptacle will be a #8 conductor.

Yes you plug a 240v appliance into 220v receptacle.

You can using a transformer, but you won't have as many amps available. 5000 watt generator @ 120v = 41.66 amps 5000 watts / 240v = 20.83 amps

Using a box that is hire voltage than what you need can cause a short, and even a fire. So using a 240V box, when all you need is a 110v receptacle, wouldn't be a good idea.

Answer for USA, Canada and countries running a 60 Hertz supply service.One 240 volt receptacle fed from a two pole breaker from the distribution panel. The size of the breaker is determined by the load current and the wire sized accordingly.

For a 7000watts or 7kw a 240V then it is 30 Amp

If the 2 hot wires are connected to either side of a receptacle, you have a 240v receptacle (assuming it's in the US). This is typically done for window air conditioners. But code requires that the receptacle have a different configuration than other receptacles in the building so you don't run the risk of plugging in a 120v device into a 240v receptacle.

I suspect you mean GFIC breaker. The dryer will not cause the breaker to fail.

You can't. I'm not sure exactly what you're trying to do, but the way it is written is not possible. It seems you might want to use half of a duplex receptacle for 120 and half for 240. This would not be code compliant, nor would it make sense. A plug designed for 240v will not even fit into a 120v receptacle. You need a 240 volt receptacle rated for the amperage you will need. Also, an existing 120v receptacle has nothing to do with your 240v receptacle. For a 240 volt receptacle, you'll need to run 2 new 120v lines (in the same cable). The existing 120v circuit cannot be used here, even if you added another 120v circuit, because when a load uses 240v, both 120v circuits supplying the 240v must be controlled by a common disconnect (a 2 pole breaker designed for 240v circuit). My advice would be to show an electrician what you want done. I'm sure they can tell you how to make that happen.

In America, a 2-pole breaker is controlling 240V. 120V per leg.

The voltage is correct, BUT, Your welder is going to draw more current than the pool pump did. The breaker, wiring, and the receptacle will have to be upgraded. In my opinion I have never seen a "temporary" connection!! ...pkazsr

Assuming a power factor of 0.85, at 240V 3 phase, 15KW load would draw a full load of 42.5 Amps. 50 Amp rating breaker will be suitable.

The 30 A breaker you seem to be describing is a 240V breaker. There should be two black wires or perhaps a black and red wire connected to the two screws on the breaker. So the breaker would trip if more than 30A was demanded by the load with 240V across the load. What you have connected to the breaker should be sized such that the total current is no more than 80% of the 30 A.

A single pole 15 amp breaker can only be setup for 120v. You need a double pole 15 amp breaker, which looks like two 15a breakers attached with a bar across the two actuators. Each leg provides 120v, or in the case of your breaker, 240v across the two legs.

Bare wires!?!?!?! For 240V you need 3 wires plus ground. Red and Black are hot, white is neutral. Don't mess with 240V if you have no idea what you're doing. It's not safe at all.

30 amp using AWG #10 wire.

Buy a new receptacle that your plug fits in. You probably need one with a neutral so look for 125/240v.

Don't understand this question. If the breaker is on, then the dryer would function normally, if the breaker your are referring to is the one for the dryer. If the breaker is off then no function. A dryer runs on 220.

For safety reasons ( and the National Electric Code) never put more than 75% load on a breaker, so for you case, 20 amp breaker x 75% = 15 amps 15 amps x 240 volts = 3600 watts 3600 watts

Copyright ยฉ 2020 Multiply Media, LLC. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.