Downsizing

[Energy-Miser]

Greetings,
I need to downsize main breaker in a resi from 200 amps to 175. Do I need to calculate the load, to make sure 175 amp is adequate? I am pretty sure I do. But for existing loads, where in the NEC would I look? Thanks, E/M.

 

[iwire]

Greetings,
I need to downsize main breaker in a resi from 200 amps to 175. Do I need to calculate the load, to make sure 175 amp is adequate? I am pretty sure I do. But for existing loads, where in the NEC would I look? Thanks, E/M.

Yes you will have to do a load calc or use recording meter or if you could get info from the power company.


Can I take a guess that your adding a PV system and your trying to back feed a 200 amp panel with more then 120%?

 

[Energy-Miser]

Yes you will have to do a load calc or use recording meter or if you could get info from the power company.


Can I take a guess that your adding a PV system and your trying to back feed a 200 amp panel with more then 120%?

Yes, exactly. We are adding roughly 46 amps at 240 volts, which will exeed the 120%. I looked to see if I could find something closer to 200 (because clearly I don't need to downsize to 175), but could not find anything. Do you know of any brand that makes larger main breaker?

 

[iwire]

Yes, exactly. We are adding roughly 46 amps at 240 volts, which will exeed the 120%. I looked to see if I could find something closer to 200 (because clearly I don't need to downsize to 175), but could not find anything. Do you know of any brand that makes larger main breaker?

Ah .. your not adding 46 amps, your adding the amperage of the breaker delivering that 46 amps. So that will likely be a 60. And no I do not think you will find anything closer to 200 than 175. See 240.6 for a list of standard sizes.

Oher options are replacing panel with higher rated or a line side tap for the PV.

 

[Energy-Miser]

Ah .. your not adding 46 amps, your adding the amperage of the breaker delivering that 46 amps. So that will likely be a 60. And no I do not think you will find anything closer to 200 than 175. See 240.6 for a list of standard sizes.

Oher options are replacing panel with higher rated or a line side tap for the PV.

Thanks. We are planning on two circuits, a 20 and a 30. On the suggestion to use power company records, do they keep track of maximum wattage used, or just energy usage on a monthly basis?