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# What is the max amps for a 4 gauge wire--can 4 gauge feed a 100A breaker box?

###### Wiki User

###### June 12, 2007 8:31PM

No number four is only good for seventy-five amps. I am pulling that out of my head, my book is in the truck. I think for a one hundred amp service you need at least number two. I will check for sure tomorrow and post it on my message board. Remember the length of the run is a factor. A quick web search will give you some calculators to help you figure this out for your application.

## Related Questions

###### Asked in Home Electricity, New Electrical Work, Modification of Old Electrical Work

### Is the amperage of a breaker for total amps combined or on each leg?

Answer for USA, Canada and countries running a 60 Hertz supply
service.
Combined. A two-pole 100A breaker will draw 50A on each leg. A
three-pole 100A breaker will draw 33A on each leg.
<<>>
People have funny concepts about electricity , the above is
totally false. A two pole 100A breaker will draw 100A on each leg.
A three pole 100A breaker will draw 100A on each leg. The number
that is marked on every breaker is the amperage that the breaker is
designed to trip at. Sheer reason should tell you that if you
wanted to protect a 240 volt load at 50 amps you would not install
a breaker that has 100 amps marked on it.

###### Asked in Home Electricity, New Electrical Work, Modification of Old Electrical Work

### Can you have 12 gauge wire that was 14 gauge wire to the light switches?

12 gauge wire is nominally sized for 20 amps and 14 gauge is
sized for 15 amps. The breaker protecting any situation where there
are mixed sizes, must protect the smallest capacity wire. So if you
have a 15 amp breaker you can mix 12 and 14 gauge wire. If you have
a 20 amp breaker you can't.
Additional
information
Using a 14 gauge wire on a 20 amp circuit is a fire hazard and is
in violation of all local building codes in the USA.

###### Asked in Home Electricity, New Electrical Work, Modification of Old Electrical Work

### What 120 volt circuit breaker can hold up to 15 amps?

A circuit breaker is designed to "trip" when more than its rated
current passes through the breaker. The current is caused by the
120V across a load of a certain resistance. The wire conducting the
current must be sized to the current. For 15 amps you need 14 gauge
wire. The breaker will be labeled and will have a current and
voltage rating printed on the breaker.

###### Asked in Home Electricity

### How do you calculate the number of breakers and their amp ratings when some are 120V and some are 240V for a given main service of 100A?

add the amps from each breaker reguardless of voltage. If the
total exceeds 80 amps, it means you cannot use all breakers at full
amp. For example: If the total equals 90, then you will have to
make sure ten amps are not being used at that time. Yes, you do
have 100 amps, however it is safest to run eighty percent of your
total amps., at one time. The number of breakers has noting to do
with the amps. You can use one breaker rated at 80 amps, or you can
use four twenty amp breakers.

###### Asked in Home Electricity, New Electrical Work

### What size wire and breaker do you need for a 5000 watt garage heater?

Look on the heater and see what amps it is pulling. That will
determine the wire size and breaker size. It must be on a dedicated
circuit.
15 amps = AWG # 14 wire with 15 amp breaker
20 amps = AWG # 12 wire with 20 amp breaker
30 amps = AWG # 10 wire with 30 amp breaker
40 amps = AWG # 8 wire with 40 amp breaker

###### Asked in Home Electricity, New Electrical Work, Modification of Old Electrical Work

### Is a two pole 30 amp breaker good for 30 amps per circuit for a total of 60 amps?

Good question. A 30 amp two pole breaker allows up to 30 amps
per leg or phase to conduct in fact provided a "total" of 60 amps.
However, 220 volt devices require the rated amperage for each leg.
So a device which requires 220 volt and 60 amps requires a two pole
60 amp breaker and the correct wire size to feed it. (# 6 gauge
wire)

###### Asked in New Electrical Work

### Can you join a 12 gauge wire to a 10 gauge wire?

Yes but there are two stipulations, one that the join or splice
must be made in a junction box that is accessible and has a
removable cover and the second stipulation is that the breaker that
is supplying the power can not be larger that the smallest
conductor. In this case no breaker larger that a 20 amp breaker as
#12 wire is only rated at 20 amps..