215.2 (A) (b) 3

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The purpose is so that if you have a small service, like a monument lighting, etc, which may only need a 20 amp service because minimal load, you cannot have a 20 amp feeder coming from the meter to your main 20 amp disconnect.

I would imagine a 55 amp limit there is because lots of old services used to be 60 amps in a tiny round can. Could possibly have a max load in a house of 30 or 40 amps. Gonna have to have at least 60 amp feeder to main
 
James L said:
The purpose is so that if you have a small service, like a monument lighting, etc, which may only need a 20 amp service because minimal load, you cannot have a 20 amp feeder coming from the meter to your main 20 amp disconnect.

I would imagine a 55 amp limit there is because lots of old services used to be 60 amps in a tiny round can. Could possibly have a max load in a house of 30 or 40 amps. Gonna have to have at least 60 amp feeder to main
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Wouldn't the feeder be after the main disconnect?
 
I think 55 amps should have nothing to do with it. (although I can see the correlation with older 60 amp minimum service)
If the feeder is carrying the total load of the service, shouldn't the feeder be rated for that load also?

215.2(A)(2) Ampacity Relative to Service Conductors

This may be a little off target with the OP's question but I will present it anyway. I suggest reading art. 310.15(B)(6) very carefully. Here is what I understand it says I can do. Scenario: Single family dwelling--One meter with 2 - 200 amp discos (400 amp service). The disco has feed...
forums.mikeholt.com
 
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Apologize... I don't think that link I posted has anything to do with the question and my edit time has expired.
 
mbrooke said:
So why must it equal the service size?
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It's taking the total load supplied but the service.
And that doesn't make sense because you can have smaller service conductors, then after your main disconnect to a panel would need to be sized larger. (correct?)
 
I just confused myself. Lets say you have 4/0 AL (180-amp) 200 amp service. It goes to a disconnect. From that disconnect to the main panel can it be 180 amp wire or does it need to be 200 amp rated wire? Thought 200 amp but just confused myself with 4/0 SER. Man I made a mess of this post. Calling it a day.
 
Ok, think I fixed my brain burp.

ritelec said:
I just confused myself. Lets say you have 4/0 AL (180-amp) 200 amp service. It goes to a disconnect. From that disconnect to the main panel can it be 180 amp wire or does it need to be 200 amp rated wire? Thought 200 amp but just confused myself with 4/0 SER. Man I made a mess of this post. Calling it a day.
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In this case 4/0 can be use the first panel. After that point, feeder wire size would need to be rated for ocp.


mbrooke said:
Bogus rule if ask me. Nothing wrong with having smaller conductors if you've got an OCPD.
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where the feeder conductors carry the "total load". I would think you could still install lesser feeder sizes for whatever you want (several 30's or what ever), as long as your not installing a feeder that serves the ENTIRE load, which makes sense.

Good night........ Elvis has left the building.
 
mbrooke said:
Bogus rule if ask me. Nothing wrong with having smaller conductors if you've got an OCPD.
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I think you're thinking breakers, but I think the issue was small sized fuses in a main.

If you had a 60 amp service to a meter, then put in 30 amp fuses in the main pullout of a 4-circuit panel, and fed it with #10 from the meter, it could easily have fuses changed to 60 amp

But if you had a 200 amp service to the meter, and had a 100 amp panel, I think those fuses could not be easily changed to larger ones.

I think
 
James L said:
I think you're thinking breakers, but I think the issue was small sized fuses in a main.

If you had a 60 amp service to a meter, then put in 30 amp fuses in the main pullout of a 4-circuit panel, and fed it with #10 from the meter, it could easily have fuses changed to 60 amp

But if you had a 200 amp service to the meter, and had a 100 amp panel, I think those fuses could not be easily changed to larger ones.

I think
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That could be what the code is getting at now that I think about it.
 
mbrooke said:
That could be what the code is getting at now that I think about it.
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For what it's worth, this thread brings back a memory from a while back. I did a service call at a very small older house that had been rehabbed as a rental. I had to get into the panel, and I saw that it was 100-amp - but it was being fed from the meter with 10 gauge wire.

Thinking about it now, I would bet anything it originally had a small fuse box with 30 amp fuses in the pull-out main.
 
James L said:
I think you're thinking breakers, but I think the issue was small sized fuses in a main.

If you had a 60 amp service to a meter, then put in 30 amp fuses in the main pullout of a 4-circuit panel, and fed it with #10 from the meter, it could easily have fuses changed to 60 amp

But if you had a 200 amp service to the meter, and had a 100 amp panel, I think those fuses could not be easily changed to larger ones.

I think
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The feeder carries the load for the service is the statement - simple main disconnect to structure panel that has all the branch circuits of the structure. If your MDP has a buss for branch circuits & you have 1 circuit being fed from that buss along with a feeder then the minimum limit is NA. I'm betting the 55 Amp # is tied to 230.79(D).
 
mwm1752 said:
The feeder carries the load for the service is the statement - simple main disconnect to structure panel that has all the branch circuits of the structure. If your MDP has a buss for branch circuits & you have 1 circuit being fed from that buss along with a feeder then the minimum limit is NA. I'm betting the 55 Amp # is tied to 230.79(D).
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Another dumb rule:

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