6 throw rule still allowed for dwellings?

[mbrooke]

I have never come across something like this in a new home and thus I am lead to believe its not complaint. The home in question has a main panel right after the meter, but no main breaker. It only has 6 double pole breakers, and my understanding is these are supposed to meet the 6 throw rule in a way the main can be eliminated?

 

[petersonra]

225.33(A)

 

[mbrooke]

225.33(A)

Would the type of load still matter as well?

 

[petersonra]

Would the type of load still matter as well?

why does the type of load matter at all?

 

[augie47]

If it's service, I'd reference 230.71.
Primary problem I would see was having to provide a load calculation IF the sum of your breakers exceeds the service conductor rating or panel rating.

 

[mbrooke]

why does the type of load matter at all?

My understanding (though it probably is false) is that in dwellings a 6 throw main (in the newer NECs) can only feed a lighting and appliance panel board or other panel boards, but can not feed load directly. Otherwise someone could wire a small home in all MWBC and just put 6 handle ties in place skipping the main breaker?

 

[augie47]

If I read 408.36 correctly, there is nothing prohibiting the install in the '11 or earlier NEC Codes.

 

[GoldDigger]

If I read 408.36 correctly, there is nothing prohibiting the install in the '11 or earlier NEC Codes.

Mbrooke may be thinking of the situation where an MLO panelboard is allowed in a residence, with six or fewer disconnect throws, if it is service equipment. And that is then complicated by the labeling information on the MLO panelboard itself which states that it is suitable for use as service equipment IF it has six or fewer breakers and it is not used as a lighting panelboard. The latter provision is supposedly related to earlier code cycles and the labelling just has not caught up.

But, given that and given the way that residences are usually wired, I find it hard to think of a situation in which a panelboard with no main breaker would have both feeder breakers and branch circuit breakers in the first place, even if there are fewer than six total.

I guess that a small, old, house could have only six branch circuits total, in which case you might not need a main under this rule.

 

[mbrooke]

If I read 408.36 correctly, there is nothing prohibiting the install in the '11 or earlier NEC Codes.

From the looks of it seems so.

 

[mbrooke]

Mbrooke may be thinking of the situation where an MLO panelboard is allowed in a residence, with six or fewer disconnect throws, if it is service equipment. And that is then complicated by the labeling information on the MLO panelboard itself which states that it is suitable for use as service equipment IF it has six or fewer breakers and it is not used as a lighting panelboard. The latter provision is supposedly related to earlier code cycles and the labelling just has not caught up.

But, given that and given the way that residences are usually wired, I find it hard to think of a situation in which a panelboard with no main breaker would have both feeder breakers and branch circuit breakers in the first place, even if there are fewer than six total.

I guess that a small, old, house could have only six branch circuits total, in which case you might not need a main under this rule.

Bingo! That's what is throwing me off. My understanding is that if the panel only feeds subpanels, its ok. However, if this panel feeds any equipment, its considered a "lighting panel board"

The panel in question has 6 throws, however only 2 breakers feed a subpanel. The others feed an AC unit, water heater, well pump, and the 6th still has to be determined.

 

[GoldDigger]

I have not found a definition for "lighting panelboard", so perhaps you would have to go to the manufacturer or old NEC books for clarification.
If none of the branch circuits feed lighting outlets, I can see an argument that it is not a lighting panelboard.
Meanwhile look at the instructions and labels on the installed panel.

 

[mbrooke]

I have not found a definition for "lighting panelboard", so perhaps you would have to go to the manufacturer or old NEC books for clarification.
If none of the branch circuits feed lighting outlets, I can see an argument that it is not a lighting panelboard.
Meanwhile look at the instructions and labels on the installed panel.

Thanks! The instructions say listed for use as service equipment. Would a general receptacle be considered a lighting outlet, just incase?

 

[augie47]

To the Code am outlet is" A point on the wiring system at which current is taken to supply utilization equipment"
The Lighting and Appliance panelboard designation was taken out somewhere around the '05 Code.
I think the confusion my surround the wording in 408.36 that prohibits the breakers from feeding another buss in the SAME panelboard as was the case in a once popular "split buss panel".
If you never had the opportunity to meet one it makes the wording a bit odd.

 

[GoldDigger]

T
The Lighting and Appliance panelboard designation was taken out somewhere around the '05 Code.

I guess mbrooke then has a strong argument that his panelboard is not a Lighting and Appliance panelboard, since that beast no longer exists.
Whether it was one or not when installed seems to me to be a moot point. Unless it violated the listing instructions of the board at the time? Can something become compliant retroactively if it was non-compliant when installed? We usually deal with opposite direction.

 

[hurk27]

My understanding (though it probably is false) is that in dwellings a 6 throw main (in the newer NECs) can only feed a lighting and appliance panel board or other panel boards, but can not feed load directly. Otherwise someone could wire a small home in all MWBC and just put 6 handle ties in place skipping the main breaker?

This is from the 1999 NEC:

384-16. Overcurrent Protection

(a) Lighting and Appliance Branch-Circuit Panelboard Individually Protected. Each lighting and appliance branch-circuit panelboard shall be individually protected on the supply side by not more than two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard.

Exception No. 1: Individual protection for a lighting and appliance panelboard shall not be required if the panelboard feeder has overcurrent protection not greater than the rating of the panelboard.

Exception No. 2: For existing installations, individual protection for lighting and appliance branch-circuit panelboards shall not be required where such panelboards are used as service equipment in supplying an individual residential occupancy.

(b) Power Panelboard Protection. In addition to the requirements of Section 384-13, 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 on the supply side by an overcurrent protective device having a rating not greater than that 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 Section 230-71.

So at one time it was dependent upon the percentage of circuits 30 amps and less, or for existing installations above in 384-16(A) exception 2, this is where we find a few dwelling services without a main breaker.

If I read 408.36 correctly, there is nothing prohibiting the install in the '11 or earlier NEC Codes.

In 2002 384 was changed to 408 but the 10% rule was still in place until 2008 when they eliminated the wording "Lighting and Appliance Branch-Circuit Panelboard" and "power panelboard" which also removed the allowance of split buss panelboards, exception 3 still allowed existing services to not have a main panelboard protection, as does the 2011 same exception, not sure if the 2014 still allows it?

 

[mbrooke]

I guess mbrooke then has a strong argument that his panelboard is not a Lighting and Appliance panelboard, since that beast no longer exists.
Whether it was one or not when installed seems to me to be a moot point. Unless it violated the listing instructions of the board at the time? Can something become compliant retroactively if it was non-compliant when installed? We usually deal with opposite direction.

I think that's that case on this one:lol:

 

[hurk27]

I have not found a definition for "lighting panelboard", so perhaps you would have to go to the manufacturer or old NEC books for clarification.
If none of the branch circuits feed lighting outlets, I can see an argument that it is not a lighting panelboard.
Meanwhile look at the instructions and labels on the installed panel.

From the 2002 NEC:

408.14 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.

It was 384-14 in the 1999 NEC, and 408.34 in the 2005 NEC it was all eliminated in 2008 as now they are just called panelboards.

 

[mbrooke]

From the 2002 NEC:

I guess only 1 breaker can feed something like a dryer, while the rest must be subpanels. At least that's how 10% reads to me. It could be this no longer holds true in any case.

 

[hurk27]

To the Code am outlet is" A point on the wiring system at which current is taken to supply utilization equipment"
The Lighting and Appliance panelboard designation was taken out somewhere around the '05 Code.
I think the confusion my surround the wording in 408.36 that prohibits the breakers from feeding another buss in the SAME panelboard as was the case in a once popular "split buss panel".
If you never had the opportunity to meet one it makes the wording a bit odd.

Split buss panels had dual rolls, in one it was a way to provide a way to separate heating and lighting loads in a dual rate service where the utility charged less for the heating loads so the top buss was fed directly from a separate lower rate meter and the jumpers and two pole main breaker in the top buss was removed and the top buss was used to serve the heating loads, the main removed from the top would be put in the bottom buss which was for lighting loads was fed from the normal rate meter.

In a normal install the top buss would be directly fed from the meter with 6 two pole breakers (one being the main to feed the bottom buss) and the bottom buss would serve the lighting and receptacle loads, 2008 removed the allowance of these panelboards.

 

[hurk27]

I guess only 1 breaker can feed something like a dryer, while the rest must be subpanels. At least that's how 10% reads to me. It could be this no longer holds true in any case.

there were no limit on breakers spaces in a power panelboard, the allowance was for OCPD protecting the panelboard you still had to have a disconnect ahead of it just no OCPDs was required.

A Lighting and Appliance Branch-Circuit Panelboard had a limit of 42 spaces and had to have OCPD protection.

So you could have had a 42 space panel serving 19 two pole breakers and 4 line to neutral loads with a disconnect but no OCPD.

The exception 3 allows for a existing Lighting and Appliance Branch-Circuit Panelboard used as service equipment without OCPDs:

Exception No. 3: For existing panelboards, individual protection
shall not be required for a panelboard used as service
equipment for an individual residential occupancy.

The question is does this allow for it to also not have a disconnect ahead of it or just no OCPD's? I think the latter as the six hand rule has been in the NEC a very long time.

Although it was very common to see a 12 to 20 space panel without any means of disconnect or OCPD's between it and the meter, I think it was just a mis-interpretation and allowed back in the 40,50-60's but without having a code book from that time period, who knows??