ampacity of split bus panel

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Greg1707

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Location
Alexandria, VA
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Business owner Electrical contractor
I will be replacing a split bus panel at a residence. There is no main breaker on the panel and there is no main breaker at the meter. Can anyone make a guess at the ampacity of the current panel?

It has the following breakers: 70 amp/furnace, 40 amp/range, 30 amp/water heater, 30 amp/AC unit, 60 amp "main lighting."
 
Greg1707 said:
I will be replacing a split bus panel at a residence. There is no main breaker on the panel and there is no main breaker at the meter. Can anyone make a guess at the ampacity of the current panel?

It has the following breakers: 70 amp/furnace, 40 amp/range, 30 amp/water heater, 30 amp/AC unit, 60 amp "main lighting."
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I would have guessed 200amps but the feeder or service conductors look too small. The panel is probably rated 200 amp but the only way to tell is by the size of the cable in the upper right hand corner. If it's copper then I would guess it is a #2 which means 125 amps.

Is there no panel outside near the meter? This service appears to be undersized.
 
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Doh, of course it is an aluminum se cable. It certainly looks no bigger than a 1/0 which would keep it at 125 and I hope it is not smaller than that.
 
cable size

cable size

I can't check the cable markings until I remove the panel. I wanted to buy the panel before arriving on the job, therefore my question. I did a load calculation based on 1,500 square feet and assuming that the electric furnace is 56 amps? Is that a reasonable assumption.

Based on those numbers and using the calculator on this website I came up with a load of 163 amps.
 
Greg1707 said:
I can't check the cable markings until I remove the panel. I wanted to buy the panel before arriving on the job, therefore my question. I did a load calculation based on 1,500 square feet and assuming that the electric furnace is 56 amps? Is that a reasonable assumption.

Based on those numbers and using the calculator on this website I came up with a load of 163 amps.
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Greg it seems you need to do a service change. Just get a 200 amp panel. Will the AHJ allow the panel location where it is now without OCP on the outside? It is hard to tell but if that panel is right at the exterior wall then I would guess you are okay but I still think you need an upgrade.
 
service

service

The meter is on the other side of the wall so it is close by. The meter is fed by an underground lateral. This is a townhouse community. Should I be concerned about the POCO's wiring to the meter or can I just increase the size of the service entrance conductors and the panel?
 
Greg1707 said:
The meter is on the other side of the wall so it is close by. The meter is fed by an underground lateral. This is a townhouse community. Should I be concerned about the POCO's wiring to the meter or can I just increase the size of the service entrance conductors and the panel?
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If you don't have 200 amp service conductors coming in to the panel and have to change them the meter base will also have to be changed. And that will bring the POCO in to do a disconnect for you so you can change the base out.

Edit:
After looking closer at the picture the grounded service conductor appears to be 4/0 aluminum. But make sure of it.
If it is I'd say you're good to go.
 
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Greg1707 said:
The meter is on the other side of the wall so it is close by. The meter is fed by an underground lateral. This is a townhouse community. Should I be concerned about the POCO's wiring to the meter or can I just increase the size of the service entrance conductors and the panel?
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Greg the underground from the poco is not your concern. They have there own rules.

As far as the meter base-- if it is an underground from the poco then I would bet the meter is 200 amp rated. I have never seen a 100 amp meter base that was allowed by the poco for underground.

If those se conductors are 4/0 I'll eat my shirt. Seriously they look much smaller to me-- compare them to the 60 amp wire used for the split buss feed-- Maybe it's right-- the size should be written on the cable jacket. You will not find it on the conductors themselves.
 
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3/0 sec

3/0 sec

I replaced the panel yesterday. The incoming SEC was 3/0. Thanks to all of your advice. This forum is very helpful.
 
Greg1707 said:
I replaced the panel yesterday. The incoming SEC was 3/0. Thanks to all of your advice. This forum is very helpful.
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Boy, my judgement is off, at least I don't have to eat my shirt. :grin:

What size panel did you go back with? 3/0 alum is an odd size
 
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