408.36(a)

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raider1

Senior Member
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Location
Logan, Utah
I have run into a situation that I would like the members to weight in on.

Here is the situation:

There is a new house with a 200 amp meter panel combo. In the panel section there is no main breaker, just busses from the meter section to the panel section. The contractor then uses the 6 disconnect rule in 230.71(A) and installs 2 100 amp breakers to feed two interior panels. Then they install 2 single pole 20 amp breakers to feed ouside receptacles and one 2 pole 30 amp breaker to feed an A/C unit.

This set up seems to be a lighting and appliance branch-circuit panelboard and therefore must meet the requirements of 408.36(A) and be protected by no more then 2 breakers. Am I missing something?

What is the substantiation for the rule in 408.36(A)?

Has anyone else had issues with this set up?

Thanks, Chris
 

dlhoule

Senior Member
Location
Michigan
It would appear to me that they are saying that there are 5 service disconnects. 2 of which are feeding panelboards and 1 feeding AC unit with other 2 feeding outside plugs/lights?

It seems okay to me.
 

infinity

Moderator
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Location
New Jersey
Occupation
Journeyman Electrician
Then they install 2 single pole 20 amp breakers to feed ouside receptacles and one 2 pole 30 amp breaker to feed an A/C unit.

The inclusion of these circuits eliminates the possibility of this being a Power Panelboard and therefore eliminates the exception to 408.36(B). Unless these circuits are removed the Lighting and Appliance Branch-circuit Panelboard requires a main OCPD.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
infinity said:
The inclusion of these circuits eliminates the possibility of this being a Power Panelboard and therefore eliminates the exception to 408.36(B). Unless these circuits are removed the Lighting and Appliance Branch-circuit Panelboard requires a main OCPD.

That is how I have read this section.

I understand the requirements of 408.36(A), but would like to know what the inherent dangers of this installation are?

If I were to eliminate the 2 single pole 20 amp breakers would this make this installation safer?

Chris
 

jwelectric

Senior Member
Location
North Carolina
raider1 said:
That is how I have read this section.

I understand the requirements of 408.36(A), but would like to know what the inherent dangers of this installation are?

If I were to eliminate the 2 single pole 20 amp breakers would this make this installation safer?

Chris

I won?t debate whether it would be safer or not but it be code compliant.
 

dlhoule

Senior Member
Location
Michigan
Can we tap off of this bus into a 30 A disconnect fused at 20 A? Now we have the same basic situation: all service equipment. I am not saying that a panelboard cannot be used as service equipment (it can), but in Chris's example, it does not meet the qualifications for a panelboard. Why doesn't it meet qualifications as service disconnects? If you were coming out of there with 1 200 amp breaker feeding everything, would it be consided a panelboard or service disconnect?
 

infinity

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Location
New Jersey
Occupation
Journeyman Electrician
Why doesn't it meet qualifications as service disconnects? If you were coming out of there with 1 200 amp breaker feeding everything, would it be consided a panelboard or service disconnect?


It would meet the qualifications of a power panelboard if it did not contain the 2-20 amp circuits which have neutral loads. A power panelboard by the exception in 408.36(B) allows it to be used as service equipment. This means that as a power panelboard it does not require a main. Once you connect the two 20 amp circuits with neutral connections the panelboard now becomes a Lighting and Appliance Branch-circuit Panelboard and that requires a main OCPD.

Here are the definitions of the two panelboards:

408.34 Classification of Panelboards.
Panelboards shall be classified for the purposes of this article as either lighting and appliance branch-circuit panelboards or power panelboards, based on their content. A lighting and appliance branch circuit is a branch circuit that has a connection to the neutral of the panelboard and that has overcurrent protection of 30 amperes or less in one or more conductors.
(A) Lighting and Appliance Branch-Circuit Panelboard. A lighting and appliance branch-circuit panelboard is one having more than 10 percent of its overcurrent devices protecting lighting and appliance branch circuits.
(B) Power Panelboard. A power panelboard is one having 10 percent or fewer of its overcurrent devices protecting lighting and appliance branch circuits.

Here is the exception to 408.36(B):

(B) Power Panelboard Protection. In addition to the requirements of 408.30, a power panelboard with supply conductors that include a neutral, and having more than 10 percent of its overcurrent devices protecting branch circuits rated 30 amperes or less, shall be protected by an overcurrent protective device having a rating not greater than that of the panelboard. This overcurrent protective device shall be located within or at any point on the supply side of the panelboard.
Exception: This individual protection shall not be required for a power panelboard used as service equipment with multiple disconnecting means in accordance with 230.71.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
So I guess what I am saying is maybe there should be the same exception to 408.36(A) as there is to 408.36(B) for panels used as service equipment.

Exception No 2 to 408.36(A) eliminates the need for individual protection of a lighting and appliance panelboard in existing panelboards, where such panelboards are used as service equipment in supplying an individual residential occupancy. Maybe this needs to be expanded to include new installations as well as existing.

I might have to submit a proposal for the 2011 code.

Chris
 

jwelectric

Senior Member
Location
North Carolina
Chris

Have you ever worked on an old split bus panel?

Have you ever seen an old split bus panel with the top filled with single pole breakers?

Here in lies a lot of the answers to your questions.
 

RB1

Senior Member
My guess at the theory

My guess at the theory

I think the rationale for this code requirement is based on the fact that lighting and appliance branch circuits could be arranged in the panelboard so that the bus of the equipment could be overloaded. Small blocks of neutral conected load could be "stacked " on one bus.
 

dlhoule

Senior Member
Location
Michigan
Can we put a 200A breaker in and come off that breaker into a gutter and feed 2 100A disconnects along with 2 30A disconnects with one of the 30As fused at 20A? Does a service disconnect have to be classified as a panelboard?

If the 30A AC breaker is using the neutral, it would still fit definition of Lighting and Appliance branch circuit panelboard even with 1p breakers removed.

If you used 2p 20A and fed fused disconnect for outside outlets, would that be acceptable?

Where does it say that service disconnects have to also be panelboards?
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
I think you have it backwards. Service equipment must be listed as Suitable for Use as Service Equipment. It can be a single disconnect, or a panelboard, or a combination of those. The problem with panelboards is if they are lighting and appliance panelboards, they must have only one or two main breakers.

If you put a 200A breaker in this system, that becomes your disconnect and from that point on none of the lighting and appliance panelboards are required to have a main.

If you keep the meter and bus panel that has 6 double pole slots as is and decide to extend that bus (unfused) to a separate 30A disconnect box, I think you could do that. But, you have to meet the following restrictions:
* The disconnect would have to be listed as Suitable for use as Service Equipment.
* If that disconnect has room for only 2 breakers, it could probably have two 20A single pole breakers and be OK.
* You'd have to make sure no more than 4 breaker were installed in the 200A meter panel because you can't have more than six total.

If you tried to do the same thing by putting a double pole 20A or 30A breaker in the meter panel, this wouldn't be allowed because the meter panel becomes a lighting and appliance panelboard in this case. Why one is safer than the other, I can't answer... I don't like working in live service panels whether the breakers are over or under 30A.
 

M. D.

Senior Member
Where are the two 100 amp breakers mounted?? In the combo meter socket?
if the are why would they not serve as a main disconnect?
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
Yes, they could be the disconnect. You could have up to six breakers in that panel acting as your disconnects. You could have two 100A breakers, a 40A range breaker, a 30A AC breaker, a 30A water heater breaker, and be OK. But put a breaker that is 30A or less that has a neutral in its circuit and now you have a violation of lighting and appliance panelboard rules.
 

M. D.

Senior Member
Mark , I'm still unclear as to how many panels we have in this example. In other words if the 2 - 100 amp brks are in a meter combo and they feed two remote panel boards , is there an issue?
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
No. The disconnect is the meter panel. It can have one or two brekaers if its a Lighting and Appliance panelboard. If its a power panelboard, you can have up to 6 breakers. The other panels don't matter and you could have more of them as long as the feeders are over 30A for this meter with no single main.

How this meter panel is classified (Lighting & Appliance, or Power) depends on what size of breakers you put in it and whether they have neutrals or not.
 
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