My main breaker is 100A at 240 volts. I've always been confused about
this. Does that mean I can use up to 100amps at 240volts, OR up to 200
amps at 120 volts?

Or does is the limit 100amps at either voltage?

On Wednesday, July 17, 2013 3:41:15 AM UTC-4, wrote:
My main breaker is 100A at 240 volts. I've always been confused about

this. Does that mean I can use up to 100amps at 240volts, OR up to 200

amps at 120 volts?



Or does is the limit 100amps at either voltage?


Physically there is never more than 100 amps flowing in
the service. However, if the 120V loads are balanced, meaning
there is an equal load on both hot legs, then you can have
100 amps flowing through each of those loads, making it
appear like it's 200 amps at 120V.

For a simplified version, think of a 240V voltage source
connected to two 1.2 ohm resistors that are in series.
There is 100 amps flowing in the circuit, with 120V
appearing across each resistor. So, each of those resistor
loads has 100 amps going through it, with 120V appearing
across each.

For you to get 200 amps at 120V out of your service, 100
amps of load must be on each leg. If you put all the 120V load
on one leg, you'd only get 100 amps. That 100 amps would be
coming in on the one hot and going back on the neutral.
If you put say 70 amps on one leg, 50 amps on the other,
then you'd have the difference, 20 amps, flowing back in the neutral.
But there is never more than 100 amps of total current.

On 7/17/2013 3:41 AM, wrote:
My main breaker is 100A at 240 volts. I've always been confused about
this. Does that mean I can use up to 100amps at 240volts, OR up to 200
amps at 120 volts?

Or does is the limit 100amps at either voltage?

You have a 100 amp main breaker.
You have a 120/240 volt single phase 3 wire service
Your main breaker limits the amperage to 100 for each of the two
ungrounded legs
This service will allow either a total of 200 amps @ 120 volt or
100 amps @ 240 volt.
What you have is considered a 100 amp service

"RBM" wrote in message ...
On 7/17/2013 3:41 AM, wrote:
My main breaker is 100A at 240 volts. I've always been confused about
this. Does that mean I can use up to 100amps at 240volts, OR up to 200
amps at 120 volts?

Or does is the limit 100amps at either voltage?

You have a 100 amp main breaker.
You have a 120/240 volt single phase 3 wire service
Your main breaker limits the amperage to 100 for each of the two
ungrounded legs
This service will allow either a total of 200 amps @ 120 volt or
100 amps @ 240 volt.
What you have is considered a 100 amp service

Nicely said! I get it.

Tomsic

On Wednesday, July 17, 2013 7:08:34 AM UTC-4, RBM wrote:
On 7/17/2013 3:41 AM, wrote:

My main breaker is 100A at 240 volts. I've always been confused about

this. Does that mean I can use up to 100amps at 240volts, OR up to 200

amps at 120 volts?



Or does is the limit 100amps at either voltage?



You have a 100 amp main breaker.

You have a 120/240 volt single phase 3 wire service

Your main breaker limits the amperage to 100 for each of the two

ungrounded legs

This service will allow either a total of 200 amps @ 120 volt or

100 amps @ 240 volt.

I'd add the caveat that it only allows 200 amps @ 120V
if the loads are exactly balanced on both legs, ie you
have 100 amps of load on one leg, 100 amp on the other.
If you had a bunch of large loads all on one leg and
tried to pull 110A @ 120V, it would exceed the circuit
and breaker capacity.





What you have is considered a 100 amp service

On 7/17/2013 9:09 AM, wrote:
On Wednesday, July 17, 2013 7:08:34 AM UTC-4, RBM wrote:
On 7/17/2013 3:41 AM, wrote:

My main breaker is 100A at 240 volts. I've always been confused about
this. Does that mean I can use up to 100amps at 240volts, OR up to 200
amps at 120 volts?
Or does is the limit 100amps at either voltage?
You have a 100 amp main breaker.

You have a 120/240 volt single phase 3 wire service

Your main breaker limits the amperage to 100 for each of the two

ungrounded legs

This service will allow either a total of 200 amps @ 120 volt or

100 amps @ 240 volt.
I'd add the caveat that it only allows 200 amps @ 120V
if the loads are exactly balanced on both legs, ie you
have 100 amps of load on one leg, 100 amp on the other.
If you had a bunch of large loads all on one leg and
tried to pull 110A @ 120V, it would exceed the circuit
and breaker capacity.


True, it would be really hard in a residential application, with random circuits of resistive and inductive loads, to balance it enough to get close to the limit of both legs

my neighbor has a 200 amp service and some years ago he was tripping his main during christmas outdoor light season. he was a true grizwald

turned out his main was very unbalanced, a few minutes with my clamp on ampmeter fixed his all up......

Do you think Griswold was unbalanced?

Double entendre, cue the drummer.
..
Christopher A. Young
Learn more about Jesus
www.lds.org
..
..
"bob haller" wrote in message ...
my neighbor has a 200 amp service and some years ago he was tripping his main during christmas outdoor light season. he was a true grizwald

turned out his main was very unbalanced, a few minutes with my clamp on ampmeter fixed his all up......

On Wednesday, July 17, 2013 8:14:05 PM UTC-4, Stormin Mormon wrote:
Do you think Griswold was unbalanced?



Double entendre, cue the drummer.

That's who I figured Bob's neighbor must be too. LOL
That was a great movie.




.

Christopher A. Young

Learn more about Jesus

www.lds.org

.

.

"bob haller" wrote in message ...

my neighbor has a 200 amp service and some years ago he was tripping his main during christmas outdoor light season. he was a true grizwald



turned out his main was very unbalanced, a few minutes with my clamp on ampmeter fixed his all up......

(Family trudging through the snow.)
"Dad! I can't feel my legs...."
"That's all part of the experience, Rusty."

http://www.imdb.com/title/tt0097958/

..
Christopher A. Young
Learn more about Jesus
www.lds.org
..
..
wrote in message ...
On Wednesday, July 17, 2013 8:14:05 PM UTC-4, Stormin Mormon wrote:
Do you think Griswold was unbalanced?



Double entendre, cue the drummer.

That's who I figured Bob's neighbor must be too. LOL
That was a great movie.