Total Amps and missing AC breaker

  1. I just wanted to get clarification on calculating total amps if there is no main disconnect. The service to the house is 200amps at the meter, but there were only 2 breakers at the main panel a 100 amp to the subpanel and a 20 amp breaker for the Garage. Does this indicate that the service at the house is only 120 amps.

  2. The main panel and the subpanel did not have a breaking for the AC. But the disconnect at the unit looked to be a 60amp breaker by the marking on it’s side that indicated 60A. This it ok that there is no breaker at the main panel or sub?

A resource for you to review.

That is a non fused AC disconnect, Square D. It is rated for 60 amps but that is NOT a circuit breaker, it is just a switch, for service disconnecting means. Your picture is too fuzzy to read but it should state the on the side. If it were an overcurrent protective device, the rating would be stamped on the handle.

There should be a circuit breaker ahead of this disco, but I don’t really see on in your pics.

OK David I just got one from my shed. The label on the front next to the handle says “Caution: Provides No Overcurrent Protection”

The label on the side says “Molded Case Switch QO 200 60A …Requires Overcurrent Protection of equivalent rating”

Since there doesn’t appear to be a breaker anywhere for it or for another sub panel, when you opened the panels did you see a double tap on the mains?

You can’t add-up the breaker ratings to determine the service capacity. The service capacity is determined by the lowest rated component of the service equipment, such as the panel rating, SEC size, etc. Mike gave you a good link.

It’s a good practice to read the information provided on equipment. As Brian stated, the AC “breaker” is in fact, just a switch. It provides no over-current protection to the system.

As you can see in my original photos there is not label that indicates an AC unit. I have also attached a photo to show that were are no apparent double taps. This is a newer home built in 2005. Should I recommend that it appear that the AC unit does not have any overcurrent protection and needs future evaluation by an electriciton.


I have read over the information provided in that link and I understand that to determine the service rating I need to determine the lowest rated component. So here is my question is if the The Panel, the meter , SEC size, etc. are all rated 200amp, but there is not service disconnect and there are 2 breakers one rated 100 amp for a sub and the other is 20 amp for that garage GFI. Is the service 120 amps. I understand that if I had 4 breakers that totaled 250 amps that the service amps would only be 200amps because of the lowest rated component. I hope that this clarifies my true question.

David, the label on the main service panel(with the 100 and 20) will determine your service size assuming you have correctly identified the meter and SE cable to be 200A.

That may be a 150A main panel but I can’t read the label.

You still can’t add breakers to determine service size.

Michael, thank you for the clarification and the web link.

You also haven’t determined where the over current protection is for the AC unit which should also be noted in your report.

If the meter, panel, and subpanel are rated 200 amps then the next step is to determine the wire size to the main panel. If the wire size is 2/0 cu or 4/0 alum it is a 200 service, if the wire size is #1 cu or 2/0 alum it is a 150 amp service (see Table 310.15(B)(6) NEC) for other wire sizes and amps. The breakers in the main panel do not determine the service size in this case. You could add 4 more breakers to the main panel giving it 6 throws as long as the connected load does not exced the total calculated load.
As for the A/C If it is a split unit it could be a non coincidental load Ex. Electric Heat strip does not run when the cooling is called for and compressor does not run when the electric heat is called for. Therefore The breaker for the air handler could be feeding the air handler and then to the compressor. But I would need more info to determine that. There could even be a small panel at the air handler. Just a possibility, but like i said more info is needed.

This is a Gas fired Heater with an air handler that is plunged into an outlet that is protected by a fuse and there was not small panel in the attic were the unit was located (i double checked by reviewing my pictures).

The A/C breaker seems to be a mystery since the heat is gas. Good luck on this one.

The panel directory could be mis-labeled?

I bet the 25 amp 2 pole breaker is for the ac.
Turn the breaker off, then test the ac.

I don’t even see a 25A 2pole. I see a 20 amp 2 pole, with #12’s attached to it. The wires in the AC disco look to be #6 SEU, or #8 at the least.

If anything, I would guess the oven is gas and that 50A is really for the AC. But from here it’s just a crap shoot.

I was also thinking that the 50A labeled oven may have been for the AC, because the kitchen had a gas range. Still you would think that a house that is only 3 years old would have both options. I called out that I was unable to locate the overcurrent protection for the AC unit and it needs further evaluation by a electrician or HVAC tech.

No. When we wire houses, we wire to what is in the plan. We don’t throw in extra stuff at our expense just to be nice, especially something as expensive as a 50 amp circuit. Being only 3 years old means nothing.

Now, if you had said it was a high end custom home, that might be different. Although, I’ve still noticed that a million dollar home and a $100K home still get the same $9 fart fan in the bathroom.

It’s kind of like buying a car, you want more options, you pay for them.

It would be an easy mistake to label the 50 amp circuit “Range” since 90% of the time that’s what it is for.