200 Amp Breaker serving as the shutoff???

[Slowmo079]

Hi everyone; I haven't posted before, hope this is the correct spot. Anyway, I was wondering if you could help me out with something that could potentially be obvious to everyone except me.

Say we are eliminating an old 60a service - fuses to breakers. We are re-doing everything, moving the meter to outside from inside etc.. Calculated load on the existing home is much less than 100 amps. Customer opts to upgrade to a 100 amp service instead of a 200 amp service because the price difference is significant due to what is needed for the mast and feeder piping etc.

So, will NEC allow me to use a 200 amp MCB (with the 8 space panel and feed thru lugs) as the emergency shut off on the exterior and jump off the feed thru lugs with my 4 AWG so long as I land immediately inside the house into a 100 MCB load center? Seems legal per 240 outside tap rule, but I also feel like I am missing something obvious here.... P.S. I'm aware this isn't ideal, a 100 amp version of this meter main combo is not available to me in this scenario.. Thanks in advance

 

[hillbilly1]

Why not 200 amp or 150 amp mast, 100 amp breaker to feed the panel inside, MLO or MB? Price difference between a 200 amp mast and 100 amp should only be wire, unless mast is not supporting the drop. Aluminum or Copper?

 

[mopowr steve]

Feeder tap rules are ok to use in your situation from meter/disco to inside panel. But your conductors in the mast must be sized for the 200 amp main breaker. So at this point you might as well install a 200 amp panel and feeder conductors inside and give them plenty of expansion for future loads.

 

[winnie]

But the point here is that you have a 100A service with a 100A main breaker but a 200A breaker serving as the emergency disconnect.

Is there any way to make thus kosher sizing the service per the 100A main.

Jon

 

[Slowmo079]

Hey, thanks for the reply.

I get what you are saying. Sometimes a 200 amp mast here can be very cost prohibitive. The picture I attached is a hypothetical situation based around the fact that I cannot find a meter combo unit that has 100a main circuit breaker with the 8 space panel, feed through lugs and a lever bypass. Can only find this arrangement with a 200a main.

My question is, can a 200amp breaker serve as the emergency shutoff for a 100amp service in the described situation? thanks again

 

[Slowmo079]

Feeder tap rules are ok to use in your situation from meter/disco to inside panel. But your conductors in the mast must be sized for the 200 amp main breaker. So at this point you might as well install a 200 amp panel and feeder conductors inside and give them plenty of expansion for future loads.

Ya, thats what I'm wondering - you happen to have a code ref for that by chance?

 

[mopowr steve]

Except you have no control over what other loads he may add to the breaker spaces just after the 200 amp main disconnect breaker. Therefore, I believe in this situation you have a 200 amp service with a 100 amp feeder tap to an inside ( sub panel ).
If there were no additional breaker spaces between the service/emergency disconnect and sub-panel and there was a 100 amp main breaker in the sub-panel one could argue that what is proposed would be compliant.

 

[Slowmo079]

Except you have no control over what other loads he may add to the breaker spaces just after the 200 amp main disconnect breaker. Therefore, I believe in this situation you have a 200 amp service with a 100 amp feeder tap to an inside ( sub panel ).
If there were no additional breaker spaces between the service/emergency disconnect and sub-panel and there was a 100 amp main breaker in the sub-panel one could argue that what is proposed would be compliant.
[/QUOTE

Thanks, that's what I was missing and it makes sense. Damned if I can't find that code reference though. Anyhow, thanks

 

[mopowr steve]

Because the “service” ends at the load side terminals of the service/emergency disconnect breaker. That main breaker is the size of your service.
The extra breaker spaces themselves are just some of the “feeders” under tap conductor rules as well as the load side lugs for your connection to a sub panel.
In order to to say your service is 100 amp you must be able to say that the feeder controls 100% of the dwelling load. You can’t positively confirm this to be true when someone can come along and sock another feeder breaker in the disconnect.
Therefore, adding load to your calculation. And causing you use proper sizing of feeder conductors because you will not be able to use the 83% rule for dwelling service/feeder conductors.

 

[Slowmo079]

Because the “service” ends at the load side terminals of the service/emergency disconnect breaker. That main breaker is the size of your service.
The extra breaker spaces themselves are just some of the “feeders” under tap conductor rules as well as the load side lugs for your connection to a sub panel.
In order to to say your service is 100 amp you must be able to say that the feeder controls 100% of the dwelling load. You can’t positively confirm this to be true when someone can come along and sock another feeder breaker in the disconnect.
Therefore, adding load to your calculation. And causing you use proper sizing of feeder conductors because you will not be able to use the 83% rule for dwelling service/feeder conductors.

YES! Thanks for helping work through it. I couldn't get there, now I can. Much appreciated

 

[norcal]

Can the 200A breaker be changed to 125A? That is usually the smallest breaker that a 200A loadcenter will accept,125A service would not have a much higher cost unless there are local or PoCo rules and regulations that nix that idea.

 

[hillbilly1]

Can the 200A breaker be changed to 125A? That is usually the smallest breaker that a 200A loadcenter will accept,125A service would not have a much higher cost unless there are local or PoCo rules and regulations that nix that idea.

By the time you bought the 125 amp breaker and installed it, probably would have been cheaper to just do a 200 amp mast, unless it’s an unusually tall mast.

 

[JGinIndy]

Ya, thats what I'm wondering - you happen to have a code ref for that by chance?
[/QUOT

 

[JGinIndy]

I came in late on this are you looking for 230.42(B) ?

 

[Slowmo079]

I came in late on this are you looking for 230.42(B) ?

Hey, thanks for the reply. I came up with a possible violation of 230.90 A... I'm still looking at it though.

I don't believe 230.42(B) applies because the #4 meets the requirements in 230.79