Electrical panel full?

[Ron Bishop]

On an inspection that I did yesterday, 5 knockouts were available at the main electrical panel cover. A 100 amp service breaker was present, and the electrical panel was rated for 125 amps. The buyer claimed that the service panel was full. Due to the presence of the existing circuit breakers, the 100 amp service could not accommodate any more circuits, according to him. Any thoughts?

[Nick Ostrowski]

My thoughts are that he should know his role as the buyer and defer to the professional he hired to inspect the house (you). He doesn't know what he's talking about. Unless those knockouts have verbiage stamped on them by the panel manufacturer stating they cannot be used, they are available breaker slots.

[Ron Bishop]

I agree, but did not want to start a confrontation.

[Rick Cantrell]

I think the question should be;
Will the 100 amp main breaker and service cables be able to safely carry the load of any additional breakers?
If that is the question, then the panel looks like it may be full.

[Jim Luttrall]

Just be honest, "I know of no prohibition on this issue, would you care to share your source for that information?"

[Ted Menelly]

I see six breaker slots and nothing I see would keep one from adding more 15 or 20 amp breakers.

Unless the service is not even wired for a 100 breaker

[neal lewis]

I think the question should be;
Will the 100 amp main breaker and service cables be able to safely carry the load of any additional breakers?
If that is the question, then the panel looks like it may be full.

Do you really think that panel is at capacity? The 2 pole breakers look like 30 Amps. I'd say there's plenty of electrical capacity there.

Was the cover removed to see if breakers could be installed where the knockouts are?

[Jerry Peck]

There is nothing to stop you, or prohibit you, from putting in 6 more single pole breakers, or 3 more double pole breakers, or some combination thereof.

The most which will happen will be that you overload the main by pulling more than the 100 amps the main is rated for.

It is highly unlikely that it is maxed out as it sets, however, the only way to know would be for an electrician to come in and do a complete load calculation of the existing circuits and what they serve, then say 'Yep, you can put in 6 more 15 amp breakers, no problemo.' or something to that effect.

Even then, though, you can still add 6 more breakers, even if the electrician says 'Hmmm ... dunno, that'd be pushing it.' as the only thing which would happen would be you would trip the main if you tried to run too many things at one time.

If the main never trips, not a problem. If the main trips, yep, need to remove a load or two (notice that is not the same as needing to remove a circuit or two - it does not matter how many circuits are on the main, it matters how many loads and what size loads are on the main).

I often thought about, but never remembered to to it, putting some sand in a zip lock bag and carrying it with me ... :) ... so I could hand it to any clients like that and then ask them to pound on it a few times, telling them it was a test to check the amount of hot air present in the area, here is a scale, weigh it first then afterward ... :D

[Ted Menelly]

I think the term pound sand has more written after it and I don't think it is just to hit the sand alone.

[Rick Cantrell]

"Do you really think that panel is at capacity? "
Without knowing more, I would not say that it has room to add any additional loads.

"The 2 pole breakers look like 30 Amps. "
Agreed, plus 10 more 15 / 20 amp breakers

"I'd say there's plenty of electrical capacity there."
For what?
I don't have any idea what the buyer is thinking about adding. He may want to add an Electric stove, A/C or Heat pump, aux heat strips, pool, hot tub, welder, air compressor, or what, could even be everything.
The point is, it is not very likley that you can add much, if anything, to a 100 amp panel.

"I see six breaker slots and nothing I see would keep one from adding more 15 or 20 amp breakers"

Yes there is room to install more breakers.
But how much more load do you think the panel can carry?
15, 20, 30, 50, amps

[Jerry Peck]

I think the term pound sand has more written after it and I don't think it is just to hit the sand alone.


Ah, but that would be a polite way to tell them to "go pound sand". :)

Go pound sand (http://www.phrases.org.uk/meanings/go-pound-sand.html)

[Ted Menelly]

"Do you really think that panel is at capacity? "
Without knowing more, I would not say that it has room to add any additional loads.

"The 2 pole breakers look like 30 Amps. "
Agreed, plus 10 more 15 / 20 amp breakers

"I'd say there's plenty of electrical capacity there."
For what?
I don't have any idea what the buyer is thinking about adding. He may want to add an Electric stove, A/C or Heat pump, aux heat strips, pool, hot tub, welder, air compressor, or what, could even be everything.
The point is, it is not very likley that you can add much, if anything, to a 100 amp panel.

"I see six breaker slots and nothing I see would keep one from adding more 15 or 20 amp breakers"

Yes there is room to install more breakers.
But how much more load do you think the panel can carry?
15, 20, 30, 50, amps




I think Jerry answered that pretty well. I know you know this but the max amp worth of breakers is not figured just by the added breaker amps in the panel.

As fasr as how many, well 5 or 6 15 to 20 amp breakers or more and again I think Jerry answered that pretty well.

[Ted Menelly]

Ah, but that would be a polite way to tell them to "go pound sand". :)

Go pound sand (http://www.phrases.org.uk/meanings/go-pound-sand.html)

I'm sorry........................polite???????? :confused: :p

[John Kogel]

Ron get a load of this :).

This is a Canadian FPE Stab-lok panel with 100 A service.
Breakers are 40A, 30A, 20A, that's the range, dryer and water tank,
5 double 15A and 6 single 15A's, that lighting and outlets,
plus 3 20A heating circuits.

In Canada, only 12 outlets/circuit, so we use a lot of breakers lightly :) .

Now that looks like a maxed out panel. Still room for more. I recommended having an electrician look this over, and we forgive FPE's up here, which is another subject for another thread.

[Richard Moore]

My thoughts are that he should know his role as the buyer and defer to the professional he hired to inspect the house (you). He doesn't know what he's talking about. Unless those knockouts have verbiage stamped on them by the panel manufacturer stating they cannot be used, they are available breaker slots.


I agree, but did not want to start a confrontation.

Ron, with all due respect, when a client (or often an agent) voices an opinion during the inspection that you know is incorrect, you have to step up to the plate and tell them then and there, as politely as possible, that they are wrong. Otherwise, it seems to me that all you have done is postpone the possible confrontation until they get your report.

"I didn't say anything at the time because I thought it might annoy you" is going to sound a bit lame on the phone.

[Matt Fellman]

I'll bet anyone a pitcher of beer that the buyer added up the numbers on the breakers and they totalled over 100.... thus his conclusion.

[Michael Chambers]

I agree with Matt! The best response to the client's comment would be to inform him that capacity isn't cumulative. There's room for several more breakers. If you put a 30 or 50 amp load on all of them (which is not likely), then yes, you're out of capacity, but if the majority of them are 15 amp, then there shouldn't be a problem.

[John Steinke]

The existance of unused knock-outs is no guarantee that you can mount additional breakers.

Several panel makers - GE being one that comes to mind - use the same dead front on several panels. It's quite common for the knock-outs to extend well past the ends of the bussbars.

[Bill Gunther]

If we look at the basics we remember that the size of the service is the lowest common denominator of the size of the wires feeding the box, the rating of the controling breaker and the rating of the panel.
If the wires and the main breaker are rated at 100 amps and the panel is rated at 125 the true rating is 100 Amps.
That being established it is also true that the sum of the amps listed on each of the non-main breakers has nothing to do with the rating or capasity of the box. Only a detailed load calculation which is beyond the scope of a home inspection could determine if the box is overloaded. On many panels the manufacturer limits the number of breakers to be installed and there is no mention of such a violation.
Any assumtion (ass u me) by the home owner or other is not relative to the inspection and should not sway the inspector. Stick to your guns when you are right and don't be afraid to advise the client or other of the facts.

[Rollie Meyers]

That panel I would almost be willing to bet that it has 20 total spaces avail., as C-H was generous w/ their panels because of the lack of a twin breaker being made for them at the time.(But even though they are made now :mad:, the panel pictured is not marked as being able to accept them) Based on the screws for the dead front would say that panel is of 1960's vintage. BTW, why is the main off?

[Matt Fellman]

My standard response to the common question, 'is there more room in the panel?'

There are two parts to that question, physical size and available power. Physical size is the easy one. Often good news when the panel appears full but is a physically small 200A type (2 for 1 breakers). The other side, of course, is how much juice is available. As mentioned by others, that needs a load calc.

[Rollie Meyers]

My standard response to the common question, 'is there more room in the panel?'

There are two parts to that question, physical size and available power. Physical size is the easy one. Often good news when the panel appears full but is a physically small 200A type (2 for 1 breakers). The other side, of course, is how much juice is available. As mentioned by others, that needs a load calc.


That is a 100A service not a 200... I doubt there is that much of a load there, 2- 30A circuits are prob. a clothes dryer & A/C or a water heater, that is speculation on my part, but it's very unlikely that that service is overloaded or close to being so.

[Fred Warner]

For those home inspectors that would be interested, just for the sheer fun of it (and to increase your knowledge in, and familiarity of, the NEC) take a gander at Appendix D for 1 family dwelling calculations, and also Article 220 to get a feel for how ampacity is calculated.

When one figures 3 watts per square foot for lighting (which includes the 180 volt-amperes for general purpose receptacles) and the kitchen and bathroom circuits and a few appliances....100 amperes goes a long ways.

All too often the "circuit capacity" of a panelboard is mixed up with the "circuit ampacity" of a panelboard. :)

[Matt Fellman]

That is a 100A service not a 200... I doubt there is that much of a load there, 2- 30A circuits are prob. a clothes dryer & A/C or a water heater, that is speculation on my part, but it's very unlikely that that service is overloaded or close to being so.


If you read my post you'll see I'm giving an example.... talking about the most common panel I encounter and get questioned about.