Maxed-out MOCP to 100%

[stuartdmc]

Is it true that you may max out the main circuit breaker to 100% if the LCL and LML are taken in account?
For example: I have a 200a 1 phase 120/240v 42 space panel the connected loads total 140 amps with all LCL and LML taken in account, being a restaurant I?ve taken the demand factor for cooking equipment and now the total 1phase load is 109 amps. The main circuit breaker feding the panels is 125 amps. Is this allowed?
Is the 125 amp main adequate?

 

[stuartdmc]

I would like to add;
The building has an existing 600A service. There is a taped 125 amp meter main allocated for this little 1000sq. ft. space. If I must enlarge the main then I?ll have to enlarge the existing 600 amp and that is going to be VERY expensive for the owner. This is why I must be correct and buy as much Code allowance as possible.

Thanks for you feedback

 

[stuartdmc]

Is it true that you may max out the main circuit breaker to 100% if the LCL and LML are taken in account?
For example: I have a 200a 1 phase 120/240v 42 space panel the connected loads total 140 amps with all LCL and LML taken in account, being a restaurant I?ve taken the demand factor for cooking equipment and now the total 1phase load is 109 amps. The main circuit breaker feding the panels is 125 amps. Is this allowed?
Is the 125 amp main adequate?

I would like to add;
The building has an existing 600A service. There is a taped 125 amp meter main allocated for this little 1000sq. ft. space. If I must enlarge the main then I?ll have to enlarge the existing 600 amp and that is going to be VERY expensive for the owner. This is why I must be correct and buy as much Code allowance as possible.

 

[wawireguy]

LCL, LCM? Huh? Do your load calculation, that'll tell you everything you need to know.

 

[skeshesh]

I'm think what he means to ask is can he exceed the rating of a %80 breaker if it is used as a main, and I believe that answer is no.

 

[DARUSA]

It is breaker out there that is marked for ,100% rating!!
But I thing your wire have to be sized at not lest of 125%

 

[iwire]

Is it true that you may max out the main circuit breaker to 100% if the LCL and LML are taken in account?
For example: I have a 200a 1 phase 120/240v 42 space panel the connected loads total 140 amps with all LCL and LML taken in account, being a restaurant I?ve taken the demand factor for cooking equipment and now the total 1phase load is 109 amps. The main circuit breaker feding the panels is 125 amps. Is this allowed?
Is the 125 amp main adequate?

Can you clear up your terms?

I have never heard of LCL and LML.

 

[iwire]

Now I know we usually calculate in VA but for this example I used current to keep things simple.

In the above example what is the minimum size standard breaker, panel and copper THHN conductor (based on 310.16) that I can use?

 

[skeshesh]

Can you clear up your terms?

I have never heard of LCL and LML.

LCL = Long Continuous Load which is what you correctly referred to as continuous load

LML = Largest Motor Load

 

[stuartdmc]

LCL = Long Continuous Load which is what you correctly referred to as continuous load

LML = Largest Motor Load

Thank you Thats is correct.

Now does this make sense?
When implementing into your panel schedule calculations all continuous loads that run for 3 hours or more at +.25%, and all non continues loads that does not apply to the 80% rule, then the main OCPD can be maxed-out to 100%.

This if correct it will save my client a $36,000.00 service change.

 

[skeshesh]

I believe that makes sense. Make sure your feeder is sized properly as well. Also if for some reason the calculated load did exceed the ratings in a way that was marginal you could buy a %100 rated breaker to avoid using the continuous %25 multiplier for your feeder calculations. I think you could find something in the 125A range for $2000 or so, the more hands on guys can probably correct me if the price is lower or higher.

 

[skeshesh]

...%100 rated breaker to avoid using the continuous %25 multiplier for your feeder calculations...

I forgot to add that the enclosure/equip has to be rated for the %100 breaker but again I doubt that replacement would cost as much has upsizing the service (I could be wrong, someone with a better grasp of a real price of installation may chime in).

 

[stuartdmc]

I forgot to add that the enclosure/equip has to be rated for the %100 breaker but again I doubt that replacement would cost as much has upsizing the service (I could be wrong, someone with a better grasp of a real price of installation may chime in).

Thanks for your Post.
The existing meter main is rated for a maximum of 125 amp main circuit breaker, I don't know if it states it's rated at 100 or 80% of the 125 amp. I'll certainly check in to it.