Breaker panel box question.

[Okie_Bob]

Hey all, good to be back, been away for awhile.
I have a main breaker box rated for 200 amps. I have 16 10amp breakers and 2 50amp and 2 40 amp for a total of 340amps.
The 50 amp are the AC equip and the 40 amps are for stove/oven.
Can someone tell me what the code says about this? Is it a code violation to have more amp capability for a given size box?
I realize I would probably never come close to using the full rated amperage for every breaker at any one time and in fact have never tripped the main breaker in the box which is 200amps. I have been in this house for 10 years and never tripped the main breaker.

The problem came up yesterday from an inspection performed by my buyers inspector. He says this is against code. I don't believe it
but, I'm not sure. Can anyone answer this with authority? I have a really good contract with a well qualified buyer and sure don't want to lose this deal.
Okie Bob...selling out in town and heading to the lake!!!

[bayview]

   

   It's a common misconception that the sum total of the amps of all the circuit breakers installed must not exceed the service panel's indicated amp rating. This is false-- capacity is determined by load calculations, not the size or number of its breakers.

[MountainDon]

bayviewps is exactly right.

[Okie_Bob]

Thanks guys, I do appreciate the help.

[cfabien]

Remind your buyer that home inspectors are not electricians or electrical inspectors. Reiterate to them that the box is up to code and suggest they hire an electrician to inspect it if they wish.

[glenn kangiser]

I would also complain about the unqualified inspector.

[Okie_Bob]

Glenn, you are right on this and I plan to do just that. This inspector is a totally unqualified idiot. I could list a dozen other things he/she did that prove it. As far as I can tell, there are no requirements to become a home inspector and yet, they can make or break a deal. I believe most buyers just go along with their realtors recommendation on an inspector as they don't know the people or their qualifications. It's nothing but a total ripoff. Had the buyer asked, I would have gladly walked him through my house and pointed out each and every flaw I knew about. Instead, he got a report, which is literally reams of boilerplate and so far from reality as to have been made without ever seeing the house.
Ok, I'm finished with my rant. Thanks for letting me get it off my mind, Glenn.

[glenn kangiser]

Give 'em hell, BoB.

[cfabien]

You're 100% right that there is really no education or experience requirement to call yourself a home inspector. There are a couple of industry associations who try to regulate them but it's hit or miss and not mandatory. I've bought two homes and used a private home inspector both times. Even though I consider myself fairly knowledgable about homes, both inspectors pointed out at least one thing that I failed to notice. I also taught both inspectors a thing or two, usually about electrical systems/code. I am not sure I would spend the money on another one if I ever purchase another home but for most people I think they serve a useful purpose, if they're a good inspector anyway. There are certianly some out there who are totally unqualified or write unwarranted negative reports to try to get the buyer some extra cash from the seller.

[MountainDon]

If you do use an inspector at least use one that carries proper insurance so if he/she does miss something significant you have a fall back.

[PEG688]

   

   It's a common misconception that the sum total of the amps of all the circuit breakers installed must not exceed the service panel's indicated amp rating. This is false-- capacity is determined by load calculations, not the size or number of its breakers.

I asked our electricians today at lunch, to go along with bayview it's not sum total , but a sum total formula based in part on square footage , what the breakers feed also ties into the calculation , if you have thermostatically controlled electric heaters , and a couple of other things.


So IF your home insp. just took a quick look and said "Your over drawn due to to many amps" ,  on a quick add up , he is at least jumping the gun on that call.


 


   

[bayview]

   Okie-Bob - Hope this is of help . . .

   Here is a example of an electric load for a breaker box . . .

   According to the NEC, all househould wiring must have a capacity of 3 watts per sq. ft.  Included in this figure are lights and receptacles for small appliances such as, radio, tv, stereo, computer, vacuum cleaner, etc . . .

The code also requires at least two small appliance circuits.  And a special purpose circuit for the washing machine.  All other major appliances are entered into the calculations.
   
   It is highly unlikely that all the appliances and all the lights will be on at the same time.  The code derates part of the load.  Use 100 percent of the first 10,000 watts and 40 percent of the remainder.  Then add the greater of the heating or air conditioning load.

   This particular example indicates that the total load is 137.25 amps.  Even though a 150 amp box would be sufficient, I would go with a 200 amp box in case I wanted to add circuits at a later time . . .

[Okie_Bob]

Bayview, thanks for your help. A quick glance raises a few questions. Why would you have 65% heat and 100% AC as you would never have both running at those levels at the same time would you? And why would you divide by 240 vs 120V? I know P=I/E and would think you would add up the KW for the 240V loads and the KW for the 120V loads and calculate separately and add them together to get the total??? What am I missing?

[cfabien]

It looks like the list has both the heating and a/c listed, but they are not added into the total 43100 line. Rather, whichever of the two is larger is added on after the derating is done. I would presume that the 65% for the heating is applicable when the house is using point heat sources like baseboard heating and they assume they will not all be on at the same time. But for a/c since it's a single unit it is a 100% load. That's a guess anyway.

Since the service is delivering power at 240v the load calculation is divided by 240 to determine the amps in each phase. This does assume that the 120v load will be reasonably balanced between the two 120v phases, which it should be in a normal house. If you did what you proposed and added up the 120v and 240v loads seperately, then allocated the 120 loads seperately to one of the two phases, you'd end up with the same result. There is enough safety margin in the design and calculations that even if the 120v loads aren't perfectly balanced the system still works fine, so it's just sizes as if it were perfectly balanced to make the calcs easier.