I have two seperate circuits, one for four recessed lights and another for a chandelier lift. I thought I needed more power for expansion but has turned out not to be the case. I no longer need these two circuits to be seperate and would like to combine them into one. I have ran out of room in my panel and was wondering if I could combine these two circuits by putting the two wires into one circuit breaker? Or, should I use a junction box two combine the two lines and a cable from the panel to feed the junction box?
Is there advantage to using one method over another? Or, is it even permitted to combine two circuits at a circuit breaker?
I guess it depends on the code. I don't think you can typically tie two circuits into the same breaker at the terminal post of the breaker. Though I see the white and ground wire posts sometimes have 2 wires in them.
One option would be to get one of those breakers that has two circuits on one breaker. No junction boxes, no double-wiring, and one free slot in the breaker box.
No need to do that. NEC allows you to combine the two circuits in the panel. Remove them from the breakers and wirenut them together with a pigtail to a breaker. If you have a SQ. D QO panel you can take both circuit wires to the breaker.
Only if the breaker terminals are designed to accept two wires (such as a SQ.D QO).
The UL listing for a lot of residential breakers allows for 2 conductors OF THE SAME SIZE, like volts500 said. Since it is approved by UL just how is this a fire hazard?
The simple answer is, "Yes you can" - though the method may vary.
Some breakers are designed so that two wires may be attached to the terminal. Square D QO type breakers for 15A and 20A circuits are designed this way.
If the breaker is not designed for two wires to attach, you could run a short pigtail off the breaker and wirenut the two branch circuit wires to the pigtail.
It is best to avoid such junctions in the panel, but not against code (I am speaking with knowledge of the CEC, but I don't believe the NEC has such a prohibition).
In new work, two home runs to a breaker suggests poor planning and, by extension, sloppy work. However, in an existing panel where limited space may be an issue, combining two home runs on one breaker (or adding a new home run and tying it on an existing breaker) is perfectly fine IF:
- there is no restriction on either of the circuits being put on the one breaker (e.g.: a refrigerator must be on its own circuit), and - a simple load analysis shows there is the capacity
For a simple load analysis, I add up the wattage of the devices on the circuit and as long as they don't exceed 80% of the breaker rating, you are fine. A 15 amp breaker has an 80% rating of 12 amps, which is 1440 watts (assuming 120 volts). For ease of estimating, 1500 watts is the limit for 15 amps, 2000 watts for 20 amps.
In some specific cases, the actual wattage may be used (e.g.: a double 4' flourescent fixture counts as 80 watts for this calculation, though with newer 34 watt tubes, that value is on the high side).
For "general" fixtures, I use 100 watts for light fixtures and 200 watts for duplex receptacles.
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