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.
Use the junction box.
"Then said I, Wisdom [is] better than strength: nevertheless the poor
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 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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