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You should not use any wire smaller than 8 AWG COPPER in a 40 amp breaker. If you have any questions about your application, you should contact a local electrical contractor for your own safety.

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13y ago
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2w ago

For a 40 amp breaker, you typically use 8-gauge wire for 120-volt circuits and 6-gauge wire for 240-volt circuits. Ensure to consult local electrical codes and guidelines as they may vary.

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Q: What is the largest wire that will fit in a 40 amp breaker?
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Will it hurt to use a 40 amp breaker on a water heater the wire I was sold will not fit into the 30 amp on a sq. D circuit breaker?

Using a higher amp breaker than recommended can create a safety hazard. It is not recommended to use a 40 amp breaker on a water heater that requires a 30 amp breaker. You should consult with a licensed electrician to properly address the wiring issue.


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.


Would you use a 6 or 8 size cable for an electric range and will that size wire fit in a new 50 amp double pole GE breaker or would a sub panel have to be added for that size wire?

== == === === Gauge #6 wires are best for this application. The breaker and wire should fit in your main panel unless it is already overloaded. Get advice from an electrician. ----- See Discussion for additional information 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.IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS.


Can you use 8 ga wire with 35 amp breaker?

If the wire will fit into the breakers terminal without cutting off any strands from the #8 conductor, then it is OK to use that size. This situation usually happens when a larger size wire has to be used to overcome voltage drop when the load is quite a distance away.


Will a 2 pole 60 amp ITE Gould or Westinghouse breaker replace a 2 pole 60 amp T and B unit?

Yes, a 2 pole 60 amp ITE Gould or Westinghouse breaker can replace a 2 pole 60 amp T and B unit as long as they have the same voltage rating and fit properly in the panel. It is important to make sure that the replacement breaker is compatible with your specific panel model.

Related questions

Will it hurt to use a 40 amp breaker on a water heater the wire I was sold will not fit into the 30 amp on a sq. D circuit breaker?

Using a higher amp breaker than recommended can create a safety hazard. It is not recommended to use a 40 amp breaker on a water heater that requires a 30 amp breaker. You should consult with a licensed electrician to properly address the wiring issue.


Is the 30 amp breaker for a motorhome the same as for a house?

Yes, a 30 amp breaker is a 30 amp breaker. It must however be able to fit the box it is installed in.


What is wrong with using eighty amp wire on twenty amp breaker?

It will work, but the draw backs are that the larger diameter wire is more expensive and it may not fit the 20 A devices well such as the breaker itself and any branch outlets or switches. It is also harder to run because of its bigger size. The voltage drop will be less across the larger wire, so that is likely the biggest advantage if you have a long run.


Can you run 14 gauge wire off 12 gauge 20 amp breaker?

You could if it fit properly in the connector, but it would be massive overkill since you only need 12 AWG wire. You also have to make sure the load can physically accommodate that larger size wire. Every so often someone will replace an electric cooktop witha gas one. All of the new gas cooktops require a 110v outlet. The old electric cooktop may have been run with a 50 amp breaker (and probably 6 gauge wire) In order to convert this 220 v circuit to a 110v circuit we change to a 20amp breaker. Depending upon the brand of breaker sometimes the wire will fit into it. If not, we splice on a short piece of 12 gauge wire and then connect to the breaker.


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.


Would you use a 6 or 8 size cable for an electric range and will that size wire fit in a new 50 amp double pole GE breaker or would a sub panel have to be added for that size wire?

== == === === Gauge #6 wires are best for this application. The breaker and wire should fit in your main panel unless it is already overloaded. Get advice from an electrician. ----- See Discussion for additional information 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.IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS.


Can you use 8 ga wire with 35 amp breaker?

If the wire will fit into the breakers terminal without cutting off any strands from the #8 conductor, then it is OK to use that size. This situation usually happens when a larger size wire has to be used to overcome voltage drop when the load is quite a distance away.


Can you use 50 amp wire and receptacle on dyer?

It's necessary to look at the dyer to see how much current it uses, which should be on the maker's plate near where the cable enters the appliance. If it uses less than 50 amps, a 50 amp cable is all right.


Do they make a 30-40 amp two pole breaker compatible with a square d breaker?

No, if you have a Square D distribution panel only Square D breakers will fit in it.


Will a 2 pole 60 amp ITE Gould or Westinghouse breaker replace a 2 pole 60 amp T and B unit?

Yes, a 2 pole 60 amp ITE Gould or Westinghouse breaker can replace a 2 pole 60 amp T and B unit as long as they have the same voltage rating and fit properly in the panel. It is important to make sure that the replacement breaker is compatible with your specific panel model.


What circuit breaker to install for 10 amp 250 volt circuit?

For a 10 amp, 250 volt circuit, you should install a circuit breaker rated for at least 10 amps and 250 volts. A common option would be a single-pole, 10 amp circuit breaker designed for 240-250 volt applications. Be sure to check the specifications and compatibility with your specific electrical panel.


Can I replace a 15 amps fuse with a 15 amps breaker?

I believe that the wires supplying a 30 amp circuit must be at least 10 gauge. If you have 14 or 12 gauge wires going to or from your 15 amp breaker, then drawing 30 amps over it could cause a fire hazard. It's like using those cheapo non-UL certified extension cords to plug a MILLION X-mas lights into (drawing more power than the wires can handle). You also have to make sure this GFI outlet you refered to is rated for 30 amps. Do not simply swap out breakers. Overloading the wires in the circuit protected by that breaker will cause a fire. If you need a 30 amp circuit you must run #10 gauge wire.