# Feed through lugs



## 3D Electric (Mar 24, 2013)

TRurak said:


> I've got an ongoing disagreement with a co-worker. I have a 200 amp main breaker 3 phase 120/208 42 circuit panel. The panel was ordered with feed through lugs on the busses. My co-worker thinks you could feed a 200 amp main lug panel off of the feed through lugs because the main breaker in the first panel protects the second panel. I disagree with this because the main breaker panel is UL listed as a 42 circuit panelboard and you would be essentially extending that by 42 circuits. What do you guys think??


The way that was always explained to me was that load center is rated to have 42 circuit breakers. With it having a factory installed feed through lugs you would be perfectly legal to install a second load center beside it and be protected by the 200 amp main.


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## 3D Electric (Mar 24, 2013)

That's also why the new square d homelines are rated 24/48. They have 24 openings with up to 48 circuits.


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## TRurak (Apr 10, 2016)

This is a bolt-in panelboard. I thought that since it is rated for 42 circuits a feed through wouldn't be legal


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## PlugsAndLights (Jan 19, 2016)

Isn't up to the manufacturer to only sell variants that are properly certified? 
In other words, if the panel is sold with feed through lugs that means they're 
approved to be used. As long as the second panel is rated greater-than-or-
equal-to 200A everything's OK.


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## RePhase277 (Feb 5, 2008)

You are still only putting 42 circuits in the panel. What you do in the other panel fed from it is an entirely different scenario. Interestingly, prior to the 2008 NEC (I think), there was a limit of 42 circuits for any panel. I never knew why. But in the 2008 edition, that limit was dropped and immediately 60 circuit panels hit the market.


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## Nom Deplume (Jul 21, 2013)

TRurak said:


> I've got an ongoing disagreement with a co-worker. I have a 200 amp main breaker 3 phase 120/208 42 circuit panel. The panel was ordered with feed through lugs on the busses. My co-worker thinks you could feed a 200 amp main lug panel off of the feed through lugs because the main breaker in the first panel protects the second panel. I disagree with this because the main breaker panel is UL listed as a 42 circuit panelboard and you would be essentially extending that by 42 circuits. What do you guys think??


Your coworker is correct. You are not extending the capacity of the 42 circuit panelboard, you are just extending the feeder. The 200 amp breaker protects the panelboard buss and whatever is connected to the feed through lugs. 
The panel is UL listed with the feed through lugs and is code compliant.


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## Bad Electrician (May 20, 2014)

TRurak said:


> I've got an ongoing disagreement with a co-worker. I have a 200 amp main breaker 3 phase 120/208 42 circuit panel. The panel was ordered with feed through lugs on the busses. My co-worker thinks you could feed a 200 amp main lug panel off of the feed through lugs because the main breaker in the first panel protects the second panel. I disagree with this because the main breaker panel is UL listed as a 42 circuit panelboard and you would be essentially extending that by 42 circuits. What do you guys think??


Then why would they make a feed through panel? This design is utilized all the time on risers.


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## Dennis Alwon (May 9, 2009)

The feed thru install is perfectly compliant. I hate to say it but you are incorrect.


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## drewsserviceco (Aug 1, 2014)

InPhase277 said:


> You are still only putting 42 circuits in the panel. What you do in the other panel fed from it is an entirely different scenario. Interestingly, prior to the 2008 NEC (I think), there was a limit of 42 circuits for any panel. I never knew why. But in the 2008 edition, that limit was dropped and immediately 60 circuit panels hit the market.



Off topic, sort of: 

As it was explained to me at a CEU course, that rule had to do with the relation of heat dissipation and it's affect on conductor insulation. Heat rising and all, plus the close proximity of conductors/cables in the top of the can. More cables, closer proximity. 

That 42 circuit rule was developed before the quality of conductor insulation could handle the heat that they are capable of today, and it is refreshing to see the CMP recognize the improvements and make changes that make sense.


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## TRurak (Apr 10, 2016)

I guess I stand corrected! Thanks for all the input.


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