Sub panel size? Is 60 amp enough?

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ritelec

ritelec

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Jersey
I will be installing a sub panel to a Square D 200 QO residential panel.
I pretty sure the buss stabs are rated for 100 Amp (actually reading around I think they may even be rated for 225 amp)

I'm freeing up some circuits to gain space in the main panel and move them to a sub panel, I figure 7 to 10 single pole circuits (maybe also room for future circuits which I VERY MUCH think unlikely in this house).

How would I size the panel? How would you size the panel? I see many of 60 amp sub panels around like 20 circ. Also, there are probably still hundreds of thousand 60 amp services on houses.
I figure just install a 100 amp panel and be done with it, but if I can do a 60 or 70 or 80 I would rather.
I think some 100's would have to take up 4 spaces.? Yet I vaguely remember installing a 2 pole two space 100 amp at my old house years ago.

The panel is tight and crowded and if I can use smaller conductors would help out.

Thank you
 
You size the panel by doing a load calc for the circuits moved. If there are general circuits, how much square footage is covered by thise circuits. If kitchen or small appliance circuits, those are 1500 va each. Nameplate for other fixed appliances. It will be more difficult to reach thresholds that allow demand factors on a feeder with few circuits. Conversely, some circuits have a load value of zero, such as outside receptacles and bathroom receptacles.
 
A 2 pole 100 amp breaker that only takes up two slots is very common.

Are you talking about setting a panel beside a main panel because you need more spaces?
 
ritelec said:
I'm freeing up some circuits to gain space in the main panel and move them to a sub panel, I figure 7 to 10 single pole circuits (maybe also room for future circuits which I VERY MUCH think unlikely in this house).
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There should be no problem supplying ten 15a 1p circuits on a 60a 2p feeder.
 
Keep in mind a 60A 240 v panel is potentially 120 Amps worth of 120v circuitry. That's a lot of power potential, didn't read what the panel is for though.
 
If you went only by breaker handle and 80% you could figure 16 amps x 3 = 48 amps on each pole of a 60 amp breaker.

That would be (6) 20 amp circuits if they were completely maxed out. I would feel real comfortable doubling that.

For what it's worth, I'm wiring a kitchen (and more) right now in which I added a 100 amp subpanel. In it I have (20) 20 amp kitchen circuits, (2) 15 amp circuits for garage lights and bonus room, and a dual fuel range
 
Long time ago QO breakers 70 amp and up took up 4 pole spaces or 6 for three pole units, and it was across both "sides" of the panel and not 4 -6 positions on just one side.

They stopped making them maybe early to mid 1980's and they go to 125 amps with units that take up two spaces, and only to 100 amp with three pole units - taking up three spaces.

If you want over those values there is still larger frame units that take up two spaces (vertically) per pole though. They may not work so well in some older panels that might have narrower cabinet dimensions.
 
ritelec said:
I will be installing a sub panel to a Square D 200 QO residential panel.
I pretty sure the buss stabs are rated for 100 Amp (actually reading around I think they may even be rated for 225 amp)

I'm freeing up some circuits to gain space in the main panel and move them to a sub panel, I figure 7 to 10 single pole circuits (maybe also room for future circuits which I VERY MUCH think unlikely in this house).

How would I size the panel? How would you size the panel? I see many of 60 amp sub panels around like 20 circ. Also, there are probably still hundreds of thousand 60 amp services on houses.
I figure just install a 100 amp panel and be done with it, but if I can do a 60 or 70 or 80 I would rather.
I think some 100's would have to take up 4 spaces.? Yet I vaguely remember installing a 2 pole two space 100 amp at my old house years ago.

The panel is tight and crowded and if I can use smaller conductors would help out.

Thank you
Click to expand...
Still might hold true but year ago a 70, 80, 90 or a 100 amp two pole 250 volt plug in circuit breakers were always the same price so never installed a 70 to 90 amp sub panel but went to a 100 amp panel. I see no problems with installing 7 to 10 single pole breakers on a 60 amp sub panel. I would make sure that none of the kitchen, laundry,or other high drawing circuits were in sub panel. I installed a 60 amp sub panel in one car garage years ago. Have a 30 amp 240 volt receptacle for a large heater and four 20 amp circuits for receptacles & central vac. If sub panel was right next to main service panel I would try to talk the homeowner into going with a 100 amp sub panel. Suggest that it would come in handy if he ever purchases an EV car. ( Would move more circuits into a least a 20 circuit sub panel ) and install the 60 amp or what ever size needed breaker in service panel for EV charger.
 
garbo said:
Suggest that it would come in handy if he ever purchases an EV car. ( Would move more circuits into a least a 20 circuit sub panel ) and install the 60 amp or what ever size needed breaker in service panel for EV charger.
Click to expand...
That is why I need to clear out the tandems in the main panel and also acquire space for the 60 2 pole.
Thank you all.
 
There is QO 125A breaker you can put in and run that to the sub and that will be future proof.
 
garbo said:
Still might hold true but year ago a 70, 80, 90 or a 100 amp two pole 250 volt plug in circuit breakers were always the same price so never installed a 70 to 90 amp sub panel but went to a 100 amp panel. I see no problems with installing 7 to 10 single pole breakers on a 60 amp sub panel. I would make sure that none of the kitchen, laundry,or other high drawing circuits were in sub panel. I installed a 60 amp sub panel in one car garage years ago. Have a 30 amp 240 volt receptacle for a large heater and four 20 amp circuits for receptacles & central vac. If sub panel was right next to main service panel I would try to talk the homeowner into going with a 100 amp sub panel. Suggest that it would come in handy if he ever purchases an EV car. ( Would move more circuits into a least a 20 circuit sub panel ) and install the 60 amp or what ever size needed breaker in service panel for EV charger.
Click to expand...
QO used to be 15-60 amp were all same price, 70 was higher, 80,90,100 were all same price but higher than the 70, then 110 and 125 were even higher yet. Not sure how it is right now, most those I have purchased more recently were already included in small job order and a lump sum price for the entire order.
 
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