Main Lug 6 Breaker 3 Phase (6 hand operations)

electrofelon said:
Hmmm, I would say the demand numbers would be fine. Here is what the relevant sections say:

230.90 Exception No. 3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors.

220.87 Determining Existing Loads. The calculation of a feeder or service load for existing installations shall be permitted to use actual maximum demand to determine the existing load under all of the following conditions:

I don't think anything in 220 has to give us permission to use 220.87, if it did, I dont think we could ever use it.
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You got me on that one. To be fair to myself I was seizing the opportunity to make fun of the NEC and didn't check the relevant code section.
 
Just don't forget that if using 220.87 (meter usage history), you need to add 25% to that to cover the existing load. Then you add any new load (if any) by calculation on top of that. But I think the metered history can replace the calculated load once you add 25%.
 
jim dungar said:
That is wrong.

They have always said a single main OR not more than 6 breakers.
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My observation is ever since they came out with the QOM series mains type back in late 80's or early 90's that information on the label fixed inside of panel has said something to the effect they are suitable for service equipment when a main breaker is used on most or maybe even all of them.

Only panelboards I ever found since about that time that didn't have this wording were certain I line panels. Though most of them have this information on them as well. I discovered this one time when I wanted to use one for the six mains allowance and could only find limited versions that were suitable for it. That install was maybe somewhere around 2012, and I maybe haven't had to check for such suitability since then in an I line panel. QO load centers, I have always had to have a main breaker if used for service equipment. Would be handy for some temporary services with limited number of circuits to use a MLO panel, but never have found one listed for it.
 
Joethemechanic said:
Something like this

View attachment 2579926

Can the sum total amperage of the breakers exceed the amperage of the service?

Using this panel for example, could you install six 25 amp 3 phase breakers for a total of 150 amps? And if so, what are the limitations and can the sum of the amperage exceed the rating of the service conductors also?
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Am I missing something here? how are you going to put Six 3 pole breakers in a box with only 12 spaces? 12divided by 3 equals 4.
 
acrwc10 said:
Am I missing something here? how are you going to put Six 3 pole breakers in a box with only 12 spaces? 12divided by 3 equals 4.
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oops, used the wrong example. Not the box I was planning on anyway. But even if I balance the loads a little differently and have 2 single phase 240 feeders for the lights and receptacles I'm going to need an 18 space because it's an open delta high leg so there will be empty spaces.

This is my own building so I want to put a lot of thought and planning into it. Everything is operating now without a problem, I just want to clean things up a bit and get rid of my 6 fused discos. I don't do credit, I didn't even take out a mortgage to buy the whole place with 3 adjoining properties. The check I write for materials is real dollars from a bank account so I'm trying to do this as inexpensively as possible
 
Joethemechanic said:
This is my own building so I want to put a lot of thought and planning into it.
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Oh its your building, man if it were my building ..
I'd do a 3-phase panelboard with a 200A main and a 200A single phase loadcenter (or panelboard), both tapped off a service gutter or something like that.
Actually if I lived PA and it were my building I'd try to get one of those rare PECO 5-wire two-phase services just to see if I could.
 
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Yeah it's this placeshop 371.jpg314908222_497706815739618_2158925782246720736_n.jpgshop.jpg

Right now it has no main breaker, there is a trough with 6 fused discos. It had 7, but I removed one that fed the craneway because they took the crane to a new building before I bought the place. I'm in PP&L land. I used to be in PECO area and did a lot of 2 phase. My uncles owned a a 3 phase 5 wire commercial building where they made lead acid batteries. There are still some down in Philly but nowhere as many as when I was young
 
jim dungar said:
Here is a link to the SE website

Are QO(single Phase & three phase) and HOMELINE Load Centers Suitable for Use as Service Equipment? | Schneider Electric USA

www.se.com www.se.com
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All QO single and three phase and HOM load centers are marked as "Suitable for use as Service Equipment" if equipped with integral main breaker or when not more than six disconnecting means are provided and the panelboard is not used as a lighting and appliance branch circuit panelboard.

Other problem here is NEC eliminated the "lighting and appliance panelboard" quite some time ago now. I doubt there is any jurisdictions still using an NEC edition that still recognizes that. That factor was mistakenly a part of why I said what I did earlier and for some reason still have it in my mind we need a main breaker, when we no longer do. I mostly only run into this with small temporary services and commonly used a 6-8 QO load center, required using back fed main and hold down clip. Even after no longer required I pretty much always done that without even thinking about it. I have done relatively limited number of permanent services using the six main rule (in one panel), most of them involved I line panels and were usually something like 600-800 amps of service conductor and 150 amps plus main breakers installed.

Back when there still was such a thing, I recall an inspector teaching a CEU class bringing up baseball fields being one place he commonly seen people mis apply this. They would have main lug only panel with five two pole breakers going to each pole with lights on it, then someone would want a 120 volt receptacle at the main panel- that one single pole breaker made it a lighting and appliance branch circuit panelboard.
 
kwired said:
Other problem here is NEC eliminated the "lighting and appliance panelboard" quite some time ago now.
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Why is this a problem? If there is no definition then this exception can't exist.

But some area AHJs may still have this description and thus the proscriotion is still in the FAQ, which was origibally written back in 2014.
 
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