42 circuit limit?

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Dennis Alwon

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I don't particular care one way or the other. If I have that many circuits then I prefer many subs to one main box anyway.
 

bphgravity

Senior Member
Location
Florida
The rule once served a purpose but no longer is of concern. And really, the substantiation used to get the rule in the code orignialy was not all that sound:


quote:
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According to Anthony Montuori, Chief Inspector for the NY Board of Fire Underwriters, a lighting panel was restricted to 42 circuits as the result of a 1928 fire at the Waldorf Astoria. The cause of that fire was determined to be from an electric panel wired with type "R" cable whose overall heat load caused the fire. The electrical apparatus of the time could safely handle a 42 circuit panel while a larger panel could not.
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Keep in mind that 42+ circuit panelboards have been used Canada in for quite awhile now with no reported problems.

See Proposal 9-117, Log #2643 to see a full report on the rule and its reason for being removed from the code.
 

micromind

Senior Member
I think this rule is one of the most idiotic I've ever seen anywhere.

Why 42? That's got to be the dumbest number to limit circuits in a panel. If it's single phase, it has a built in imbalance. Maybe that's why they're usually 40. If it's 3PH, it isn't much better. All 3 pole breakers gives you 7 per side. Wouldn't an even number make more sense? If it's all 2 pole breakers (common in parking lot and warehouse panels), you have an imbalance. 1 pole breakers are ok, but it can be hard to arrange a mix.

I understand the reasoning behind it, but its repeal comes about 30 years too late. It's obvious to me that present code making committees have learned absolutely nothing from this, considering some of the ridiculous things they've rammed on us recently.

Sorry for the rant, I've about had it with idiots in authority.
 

iwire

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Location
Massachusetts
micromind said:
If it's 3PH, it isn't much better. All 3 pole breakers gives you 7 per side.

To me 42 works perfectly with 3 phase, 21 on each side or 7 groups of 3. But the change should be made as it was an arbitrary number.
 
With the requirement for AFCI's on most circuits, and since all AFCI breakers I've seen are full size, it would seem to be necessary to allow the panels to be made larger.

I use dozens of the Square D Homeline 20/40 meter combo panels, and was wondering what I was going to do about all the full size AFCI's. Most panel replacements require something 14 1/4" wide. We're going to need larger panels to accomplish this task.
 

Dennis Alwon

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electricmanscott said:
I could use a 50+ circuit panel on a remodel job right now. Does such an animal exist?

I don't believe any manufacturers have made them yet. The GE rep says he expects that they will probably make a 50 or 60 circuit panel.
 

iwire

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Location
Massachusetts
Square D has been making them for years as Canada never had a 42 circuit limit, all Square D has to do is ship them this way.

I think CH was the company that asked for the code change, I wonder if they are already selling them?

I actually work at a factory that has a Square D NQOB 225 amp 54 circuit panel being used as a lighting and appliance branch circuit panel, it has been there since the 80s. I have no idea how or way it ended up there. :confused:
 

Dennis Alwon

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iwire said:
I actually work at a factory that has a Square D NQOB 225 amp 54 circuit panel being used as a lighting and appliance branch circuit panel, it has been there since the 80s. I have no idea how or way it ended up there. :confused:
Is it 3 phase or single phase??? I have never seen a single phase over 40 circuits
 

iwire

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Location
Massachusetts
Dennis Alwon said:
Is it 3 phase or single phase???

The 54 is three phase.

I was standing in front of it one day thinking 'Gee something looks odd here' sure enough 54 full size spaces, all filled....couple of minis as well for that little bit extra.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
iwire said:
Check out this pdf, it shows indoor single phase load centers with up to 60 full size spaces or up to 80 poles using minis. :smile:
There's a 40-space/80-circuit panel, too. Everything that doesn't meet our present limitations begins with a C in the model number. Obviously, it stands for Canada. I wonder if it means we can't order one at all.

Yet.
 

don_resqcapt19

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Location
Illinois
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retired electrician
I actually work at a factory that has a Square D NQOB 225 amp 54 circuit panel being used as a lighting and appliance branch circuit panel, it has been there since the 80s. I have no idea how or way it ended up there.
I have installed a number of the 54 circuit Square D panels. My use was for heat trace panels where we use breakers with an "bell alarm" option. (a bell alarm option closes a set of contacts when the breaker trips but not when it is turned off) That takes up a full space but does not count as an overcurrent device so my use was still in compliance with the NEC. These panels were readily available from the local Square D distributor.
Don
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
The NEC hasn't prohibited installing 54 space panels for 3 phase "power panels", although I've been a little reluctant to spec those since I think Square D's catalog says their 54 space panels aren't UL listed.

Just think how many tandem breakers we can fit in on of those 70 space panels. :grin:
 
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