What the .... Do I have going on here

I am adding 7 circuits for a kitchen remodel. I figure I have 100 amp service but am not sure. Here is what I have, followed by my questions;

Main panel



Inside

Attachment 29568

Further inside

Attachment 38005

Panel inside garage

Attachment 24139

On door of panel

Attachment 49662

What exactly do I have going on? 90 amp service? Shouldn't the sub have a main breaker?

I Did amperage calculations for my home and came up with around 80 amps. My current sub panel is a 12 slot and is almost full. I want to add a 100 amp 20 slot unit, but realized that between 5 new 20 amp circuits and 2 existing for the ovens, I would have 140 amps worth of breakers before including all the existing and added 15 amp circuits. Is this ok? Can you have more breakers worth of amps than actual service?

Bottom line, based on what you see, can I add a larger sub panel and additional circuits with my current service?

 

It looks to me like you have an old Arrow-Hart Murray 125 amp service provided the wire size coming from the meter will support 125 amps. Was the house built in the late '60s or'70s? What size are the wires on the load side of the meter? Assuming the subpanel is under the meter, that section wasn't shown opened, the 90 amp breaker would be the main for the sub, the sub doesn't need a main installed in it. You mentioned you needed to add seven circuits, what is your existing calculated load and how much load are you adding?

 

Yes, the house was built in the 70's. Not sure what size wire is on the load side, not quite able to look at a wire and tell. The sub panel I showed is the only other panel I have, and it is not under the main that is shown. The only load I am adding is a second oven and a range hood. New Lighting is replacing higher wattage lights which should lower my load, correct? I did not calculate my current load, just anticipated new load of around 80 amps.

 

There is a lot I don't know about your home and loads, but I don't think you need to do much more than just replace the subpanel. The existing subpanel is a 12 space-24 circuit panel. I would recommend a main lug 30 space subpanel. Your anticipated new .load of 80 amps is incorrect. First of all, load is calculated in watts, but that aside, you'll maybe be adding around 30 to 35 amps to your service, but these are not continuous loads. I think you'll be fine.

Just remember, the old A-H Murray meter combo is pretty old and won't last forever. You should be thinking about maybe replacing it in the next 5-10 years. A-H Murray was a very cost effective piece of equipment in the '70s and not known even then for high quality.

 

Thanks for the response. Originally I did my load calcs using wattage and came up with around 80 amps (can't remember exactly). I will redo it to confirm. I just wanted to make sure that I can put a larger subpanel in to accept more circuits and still be up to code. Just to make sure I understand, essentially I could put a 20 space panel in and use every space (40 circuits?) and still be up to code as long as my anticipated load is less that my service?

Good to know about my current main. I will consider replacing it as well.

 

I would use a full size panel, not one like a 20/40 that needs to use tandems. A double pole breaker will eat up 4 of those spaces instead of 2 full size.

 

So I can use a regular panel and make as many circuits I want as long as my anticipated load does not exceed my service load rating?

 

Yes. You don't need a main breaker because the 90 amp breaker provides the overcurrent protection. I would use a main lug panel, but code does not prohibit using a main breaker panel either. The main breaker would just be a disconnect if you choose to use one.

 

Excellent. Thanks! You guys are the best!

 

So something like this would be a good choice?

Square D Homeline 150 Amp 30-Space 30-Circuit Energy and Automation Indoor Main Lug Load Center

 

That would work. I wouldn't recommend it because I prefer a copper bus panel and Square D Homeline panels all come standard with aluminum bus. If you are shopping at a big box homecenetr, ask if the have any copper bus main lug panels.

 

An aluminum bus panel is an economical choice if money is a consideration and should provide years of reliable service. Copper is more conductive, but is also more expensive.