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Yes, you can use a 40 amp breaker to feed a sub panel. The wire from the 40 amp breaker must be #8 or larger. If you intend to use the full 40 amps a larger conductor must be used. Conductors can only be loaded to 80% capacity in continuous load conditions. A #8 wire is rated at 45 amps x 80% = 36 amps. The suggested size would be a #6 rated at 65 amps x 80% = 52 amps.

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Q: Can you use a 40 amp breaker to feed a sub panel?
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Can you feed a 60 amp sub panel from another 60 amp sub panel?

Yes


What would happen if a 200 amp breaker is used in a 100 amp sub panel?

There are two things to think about here. First of all a 200 amp breaker will not physically fit into a 100 amp panel. This is so designed because the panel buss is not designed to conduct 200 amps before the current is cut off. A 100 amp rating on the panel is the maximum amount of current that the manufacturer states, that can be handled safely. Second if the 200 amp breaker is in the main panel then everything downstream from that breaker has to be rated for 200 amp conductivity. The wire size will have to be 3/0 from the breaker to the first over current device in the sub panel which will be the sub panel's main breaker. The sub panel can not be a load center but will have to be a combination panel. I doubt that the 100 amp sub panel's main breaker lugs would be large enough to connect the 3/0 cable.


Can you had a 20 amp breaker on your 70 amp sub-panel that has already 70 amp total on it that consist of one 50 and two 15 amp breakers and the panel has 4 available spaces out of 8?

SeeIf_a_100A_breaker_panel_has_five_15A_breakers_and_four_20A_breakers_could_this_overload_the_panel


Can a sub panel from a 15 amp breaker be used with a branch circuit with 20 amp breaker?

Answer for USA, Canada and countries running a 60 Hz power supply service. Yes you can add these two breakers to the sub panel. You will have to keep in mind the fact that if the total loading of the two breakers exceeds 30 amps the 30 amp sub panel breaker will trip. If you use the 20 amp and the 15 amp loads individually then you will be under the 30 amp feeder sub panel breaker and good to go. With feeders of 3 conductor #8 the 30 amp breaker can be increased to 40 amp. If there are large motor loads involved this answer will change as starting current has to be calculated into the equation. View discussion page for additional information.SAFETY ADVICE 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-energizedIF YOU ARE NOT REALLY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS.


Can you use 10 2 wire to come off a 60A double throw and run it to a sub panel with 2 spaces 20A each and be up to residential code?

No. the 10/2 must never be fed from anything more than a 30 A breaker. If you're planning to feed a sub-panel using 10/2, use a 30 Amp double breaker.

Related questions

What size breaker do you use for a 100 amp sub panel?

A 100-A sub-panel would be fed from a 100-A breaker.


Can you feed a 60 amp sub panel from another 60 amp sub panel?

Yes


What would happen if a 200 amp breaker is used in a 100 amp sub panel?

There are two things to think about here. First of all a 200 amp breaker will not physically fit into a 100 amp panel. This is so designed because the panel buss is not designed to conduct 200 amps before the current is cut off. A 100 amp rating on the panel is the maximum amount of current that the manufacturer states, that can be handled safely. Second if the 200 amp breaker is in the main panel then everything downstream from that breaker has to be rated for 200 amp conductivity. The wire size will have to be 3/0 from the breaker to the first over current device in the sub panel which will be the sub panel's main breaker. The sub panel can not be a load center but will have to be a combination panel. I doubt that the 100 amp sub panel's main breaker lugs would be large enough to connect the 3/0 cable.


I have a Transformer 480 primary 208 secondary feeding 1 200amp mb 42 space panel I need to feed a subpanel 6 ft away I'm thinkin feed through lug at top of bus or at feed through MB suggestions?

The sub-panel need to be fed from the main panel, by way of a circuit breaker connected to one of the breaker locations. Or if your sub-panel has a main breaker installed you can feed from the main panel with a sub-feed lug kit. This looks like a breaker, but is only a point where you can branch off the sub panel.


How do you wire a garage sub panel box from a 100 amp breaker in the house main panel?

you propaly can't sub panel from 100 amp panel. Just not enough amperage to be worth while. i had to up grade t a 200 amp main first and then I was able to take a 60 sub panel from that.


Can you put a 60amp breaker and a 50amp breaker on a 60amp subpanel just as long as they are not being used at the same time?

You can. Using these size breakers in a 60 amp sub panel might be pushing the limit for breaking the sub panels feeder breaker. The breaker feeding the sub panel will have to be no bigger than 60 amps because of the main bus bar capacity of the sub panel. It would be better to install a 100 amp sub panel and then there would be a bit of a buffer and you will have the ability to add additional small load circuits.


Can you had a 20 amp breaker on your 70 amp sub-panel that has already 70 amp total on it that consist of one 50 and two 15 amp breakers and the panel has 4 available spaces out of 8?

SeeIf_a_100A_breaker_panel_has_five_15A_breakers_and_four_20A_breakers_could_this_overload_the_panel


Can a sub panel from a 15 amp breaker be used with a branch circuit with 20 amp breaker?

Answer for USA, Canada and countries running a 60 Hz power supply service. Yes you can add these two breakers to the sub panel. You will have to keep in mind the fact that if the total loading of the two breakers exceeds 30 amps the 30 amp sub panel breaker will trip. If you use the 20 amp and the 15 amp loads individually then you will be under the 30 amp feeder sub panel breaker and good to go. With feeders of 3 conductor #8 the 30 amp breaker can be increased to 40 amp. If there are large motor loads involved this answer will change as starting current has to be calculated into the equation. View discussion page for additional information.SAFETY ADVICE 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-energizedIF YOU ARE NOT REALLY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS.


Can you use 10 2 wire to come off a 60A double throw and run it to a sub panel with 2 spaces 20A each and be up to residential code?

No. the 10/2 must never be fed from anything more than a 30 A breaker. If you're planning to feed a sub-panel using 10/2, use a 30 Amp double breaker.


Can a 60 amp main breaker be used to supply a 100 amp subpanel power so that I can take advantage of the extra curcits provided by the larger panel I'll only be using 45 amp at any time?

You can certainly use the larger breaker panel provided that you sub-feed the panel using breakers that do not exceed the rating of any down-stream device. If you have any concerns or do not thoroughly understand what you are doing, contact a qualified electrical contractor in your area.


Is a 12 gauge wire on 20 amp breaker safe for a sub panel?

Yes, if you are running it no farther than 100 feet. If you are going over 100 feet use AWG # 10 wire on the 20 amp breaker.


What size breaker do I need on the main panel to run a 2-60 amp breakers and 2-40 amp breakers on a sub panel?

You need to calculate how much the total current is likely to be at any moment. It's probable that the total load will be less than the sum of the individual breakers, 200 amps, but how much less depends on local conditions.