Too many breaker in load center

Originally Posted By: mcotten
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Inspected a 200 amp load center that had 26 mini breakers and 6 30amp 220 breakers. It also had a 100 amp breaker that was for a subpanel. The subpanel has 16 15amp breakers and 3 30amp 220 breakers. I know this is too much for a 200 amp service. I need a source to quote to back up my findings. I called GE help center for the information, but they have not responded yet. Thank you for the help


Originally Posted By: bking
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Some panels actually have the limits posted on the label. I saw a Murray 200A panel that said “no more than 200A total circuit breakers per stab”


Added with edit:
See post made below on 12-27-05

It appears that GE at least, did not intend to refer to a bus bar as a "stab"


Originally Posted By: brian winkle
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Quote:
I know this is too much for a 200 amp service.


You cannot determine the load on a service by counting the breakers. The only way to determine if the service is adequate for the load is by doing a LOAD CALCULATION.

As far as the number of breakers allowed see 384-15. As stated by another poster, the panel will usually contain information on it's maximum allowed.


Originally Posted By: bking
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I emailed GE Industrial about their label on new panels that states


" combined marked rating of circuit breakers on any one stab not to exceed 220Amps"


this was their answer:

The TM3220CCU you referenced in the case notes has 32 stabs that allow the breakers to connect to the bus bar. This is the connection of concern in the statement listed above. A single stab out of the 32 stabs in the loadcenter cannot exceed marked rating of 220A.


Originally Posted By: pabernathy
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I also believe that the NEC states that no panel shall have more than 42 switches ( ie: disconnects ) in a service panel. each one of those tandoms count as (2) breakers… so as mr.winkle has already stated…without doing the math we can’t determine the load…but we can site the fact that a panel is beyond the allowed amount of breakers per NEC if that is what you are looking for.



Paul W. Abernathy- NACHI Certified


Electrical Service Specialists


Licensed Master Electrician


Electrical Contractor


President of NACHI Central Virginia Chapter


NEC Instructor


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Visit our website- www.electrical-ess.com

Originally Posted By: pdickerson
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Michael,


I didn't see anything in your post that would indicate that there were too many breakers. If you are conerned, recommend that a licensed electrician perform a load calc (it is beyond the scope of a HI to do this). If you have any photos, maybe you could post them.


Originally Posted By: pabernathy
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Just for reference-


Art 408.15 Number of Overcurrent Devices on One Panelboard

Not more than 42 overcurrent devices ( other than those provided for in the mains ) of a lighting and appliance branch circuit panelboard SHALL BE installed in any one cabinet or cutout box.

A lighting and appliance branch circuit panelboard SHALL BE provided with physical means to prevent the installation of more overcurrent devices than that number for which the panelboard was designed, rated and approved.


Ok....Long story short.......30/40 panels are designed for max 40, 42 circuit panels are designed for 42 circuits.....If the panel label tells you the number allowed it should not be extended beyond that. Now, we know ways around that with subs and so on....However the key is ONE enclosure...Now the rating is harder to surpass unless a load calculation is done..which is outside of the scope....but in many cases a panel that is crammed packed....loaded with tandoms and so on would more than likely exceed the design factor and approved number of OCPD devices listed for the panel in question.

Hope this helps.....IN all cases when you have a panel that is expanded beyond the scope listed above...always suggest evaluation by a licensed electrical contractor. ( better for HI's to be safe than sorry )


--
Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com

Originally Posted By: dvalley
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General Lighting

Take the square footage of the house times 3va (volt-amperes)= __________ then add that number to 4500, which would be 2 small appliances and 1 laundry load.

******************************************************

Take this subtotal and determine the *total general lighting load & small appliance as follows:

Take the first 3000 at 100% 3000

Take the remainder at 35% _____
(Total general lighting load
and small appliance minus 3000)

Then add those two together to
obtain the *total general
lighting load & small appliance _____

******************************************************

Now determine the following and add them to the *general lighting load & small appliance:

Dishwasher 1200 va

Disposal 1200 va

Dryer 5500 va

Oven 8000-12000

(On the oven check the breaker size. If it is a 40 amp breaker it is 8000. If it is a 50 amp breaker it is 12000.)

Air Conditioner 5500-12000

(On the air conditioner, 700 sq ft requires 1 ton of air conditioning. A house of 2800 sq ft would require 12000 va whereas a house of 700 sq ft would only require 5500 va.)

Swimming pool 1500

Hot Tub 9000

(On the hot tub if the breaker is a 50 amp it would require 9000. If it is a 30 amp, it would require 6000.)

Electric Heaters, well pumps, and compressors would be figured out by taking the breaker size times the voltage required to use the breaker, and then times 35%. ( A single pole 20 amp breaker would result in 840 va [120 x 20 x .35=840]. A 20 amp two pole would be 1680 va [240 x 20 x .35=1680].)

******************************************************

Take the total of the above and divide it by 240 volts. The result will be the total amount of amperes needed by the house.

A house at 80 amperes or less is good for a 100 amp panel and service.

A house at 81 amperes to 90 amperes is marginal for 100 amp panel and service.

Anything over 90 amperes should be upgraded to at least a 150 amp panel and service.

A house at 160 amperes or less is good for a 200 amp panel and service.

A house at 161 amperes to 180 amperes is marginal for a 200 amp panel and service.

Anything over 180 amperes should be upgraded to a higher than 200 amp service and panel.



Here is an example of a load calculation:

The house is 2000 sq ft, therefore 2000 x 3va =6000

6000 + 4500= 10500

The 1st 3000 is at 100% 3000
The remainder of 7500 is at 35% 2625

The sum of these two is: 5625

This number is the general lighting load and small appliance.

The house has a disposal 1200
A dishwasher 1200
A electric dryer 5500
A electric oven at 50 amps 12000
A air conditioner 10000

The sum of all these appliances plus the general lighting load and small appliance is: 35525

Take 35525 and divide it by 240 volts = 148 amps

This house would require a panel and service upgrade to at least 200 amps.


--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."

Originally Posted By: Greg Fretwell
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A quick computation for the general lighting load is 3525va plus 1va per square foot (really 1.05va so round up).


That takes care of the small appliance circuits (3000va @100%) plus the laundry (1500@35%) that gives you 3525 and that never changes.
Then you are left with square footage @ 35% of 3va.

In a multifamily without the laundry start with 3000va and the 1.05 per square foot.


Originally Posted By: pabernathy
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However…we do not need HI’s trying to compute this load issue. Once you attempt to do it for your client you overstep your boundaries as a generalist…and could cause you issues.


Just wanted to say that....

I teach apprentices this weekly during the winter but would not want to have a HI attempt to do this not because they can't....but because it really goes beyond the SOP in most part.


--
Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com