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Old 06-23-2010, 04:16 PM   #1
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Service Entrance Question


I have a GE service entrance box (with the power company meter module attached) that is outside house (of course). It has a side breaker panel that says it is 125 Amp. Inside is space for 2 breakers which are present. One is 125A and presumably for inside breaker box for house service. Second breaker is 50A that runs outside hot tub.

Question: Can the 50A be "pulled" and replaced with 125A breaker for larger conductor service to a new subpanel to a new barn. At that point, put in a 50A circuit for the hot tub and other lesser circuits for lighting and a 30A 240 line for table saw?

I guess the bottom line question is...is the 125A outside box "limited" in the number of 125A circuits (except by condutor sizes and/or number of "spaces" availble) in the box?

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Old 06-23-2010, 04:31 PM   #2
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Service Entrance Question


Along with verifying the ampacity of the panel as 125 amps, the next thing to do would be to perform a demand load calculation to see if the existing service can support any additional load.

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Old 06-24-2010, 08:29 AM   #3
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thanks Jim...

so presumably, if service able to support, the change of the breaker capacity COULD theoretically be changed/increased, correct?

What is best way for non electrician (planning on calling one out when ready) to do the "computations" for the load demands analysis you mentioned?
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Old 06-24-2010, 10:30 AM   #4
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Quote:
Originally Posted by Jim Port View Post
Along with verifying the ampacity of the panel as 125 amps, the next thing to do would be to perform a demand load calculation to see if the existing service can support any additional load.
Jim, I'm asking this mainly so I know but the OP may need this too.
If this breaker panel currently has one 125A and one 50A double pole breaker and the intent is to have two 125A breaker, the ampacity of the panel needs to be 250A. - yes?
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Old 06-24-2010, 10:51 AM   #5
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The panel will have a maximum rating that it can handle safely. However, that does not mean that the wires feeding that panel are capable of the maximum of the panel. For example a 100 amp panel fed by 60 amp conductors.
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Old 06-24-2010, 12:35 PM   #6
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Hmmmmmmmmm... understood about safe capacity of conductors statement. however, than based upon your comment and corsair's the 125A and 50A breaker presently installed is BEYOND capacity for the panel and 1) I cannot change 50A to 125A (presuming load and conductor allowability) and 2) I need to have panel including power meter unit switched out to higher amp rating. is that correct?
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Old 06-24-2010, 01:44 PM   #7
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Could you post the model number of your panel?
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Old 06-24-2010, 02:19 PM   #8
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GE TL412RMC
125A

type 3
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Old 06-24-2010, 11:28 PM   #9
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Is maybe the 125 the main, and the 50 the breaker, and the box has nothing to do with you house feed?

when you flick the 125, does the house go dark or not?
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Old 06-25-2010, 12:45 AM   #10
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Originally Posted by MeanGene View Post
GE TL412RMC
125A

type 3

That is 12 space 125 amp load centre and if the M is right spot that is main breaker the R is rainproof so the type 3 is raintite box.

and I will have to double check with GE master catlog book to make sure the info is correct.

Merci,
Marc
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Old 06-25-2010, 02:46 AM   #11
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Quote:
Originally Posted by MeanGene View Post
... based upon your comment and corsair's the 125A and 50A breaker presently installed is BEYOND capacity for the panel and 1) I cannot change 50A to 125A (presuming load and conductor allowability) and 2) I need to have panel including power meter unit switched out to higher amp rating. is that correct?
This is something alot of people get wrong - confusing demand load calculation with the amp size and number of breakers.

On a service panel, there are two kinds of breakers - 1 = the main breaker, and 2 = all the other breakers.

The main breaker is what caps your entire system. It ensures that on a 200 amp service panel, no more than 200 amps total can be run from the feeders though the panel. If more than 200 amps try to sneak thru - snick - it's lights out.

Now, that 200 amp panel can feed a 125amp subpanel, 6 20amp circuits, and 6 15amp circuits. But wait, you say... 125+20+20+20+20+20+20+15+15+15+15+15+15 ... that equals 335amps! How is that possible!?!

That 125amp, 20amp, and 15amp breakser belong in the catagory "all the other breakers" It doesn't matter how many I have, all they are doing is protecting the wire that is attached to them from drawing more than 125, 20, or 15amps. Right now in my house the 125 amp subpanel circuit is actually drawing about 3 or 4 amps running two refrigerators, most of the 20 amp circuits have about 1 amp going through them total, and I have maybe 2 amps going through the 15 amp circuits at the moment. So while all my breakers running at peak capacity could flow 335 amps if allowed (they're not, remember they are fed by a 200 amp breaker), they are only flowing about 7 amps through my house at the moment.

Breaker capacity does not equal current flow! This is why you need to do a load calculation, to figure out how much power you will normally use. From that calculation, you can figure out what size panel you need, as well as sizing any subpanels correctly.

Fun fact: When I installed my new 200 amp service panel and cut over circuits from my old panel, I ran my whole house for months off a single 40 amp circuit!

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