Taps in a service panel

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mjc1060

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I was called to inspect a 100A 240V single phase residential service. In this panel attached to the bus where two lugs that had two more conductors feeding a second 100A panel. This second panel has no OCPD on the feeder conductors(these are 2' long). Both panels have 100A 2 pole main breakers. The service conductors from the meter are #3 and they feed the first panel. This seems to me a bad installation at best. Is this also a code violation and if it is where would I find it in the NEC?
 
As suggested above, you may have termination problems 110.14(A) and you may be overloading your #3 but you need a load calculation to determine that.
 
mjc1060 said:
I was called to inspect a 100A 240V single phase residential service. In this panel attached to the bus where two lugs that had two more conductors feeding a second 100A panel. This second panel has no OCPD on the feeder conductors(these are 2' long). Both panels have 100A 2 pole main breakers. The service conductors from the meter are #3 and they feed the first panel. This seems to me a bad installation at best. Is this also a code violation and if it is where would I find it in the NEC?
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Are you questioning attaching these lugs to the bus, or how they are attached?

they make panels with feed through lugs, but you could have issues with some makeshift method and listing/instructions depending on what was done.
 
Nothing that has been mentioned is a clear violation without further clarification.

First, are the conductors to the second panel tapped on the line side or load side of a service disconnecting means?

Second, what is the calculated load on the service? It is not a violation to have two panels with 100A breakers unless the calculated load exceeds the rating of the service conductors.
 
Sounds like these are connected on the line side of the SEC's which means that these are SEC's and not tap conductors. To determine if the #3 AWG conductors from the meter are of adequate size you would need to do a load calculation.
 
infinity said:
Sounds like these are connected on the line side of the SEC's which means that these are SEC's and not tap conductors. To determine if the #3 AWG conductors from the meter are of adequate size you would need to do a load calculation.
Click to expand...

seems like I heard that somewhere before :D
 
Is the issue how the wires are terminated or whether the # 3's are right size wires or both ? Would it be any different if the SEC's entered a trough first and then split off utilizing insulated Polaris bugs into the two MBP's ? I've seen it done many times for 2 family houses. Granted a load calculation should be done (echo) but what are the chances that either or both of those panels are going to draw that much current ? But, then again, we don't know the whole story.
 
Zinsco Panel Board

Zinsco Panel Board

This is a Zinsco panel board and I don't know if it is listed for the taps on the bus. I did not do a load calculation but it is a single family home and I don't think the load exceeds 100A on both panels. My question would be can you attach lugs to the panel board.
 
mjc1060 said:
This is a Zinsco panel board and I don't know if it is listed for the taps on the bus. I did not do a load calculation but it is a single family home and I don't think the load exceeds 100A on both panels. My question would be can you attach lugs to the panel board.
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Depends on the instructions for the panelboard. I would say for a residential scale panelboard, especially a Zinsco, unless there's an original label that clearly indicates that lugs can be installed in the position where they exist, then it's a violation of 110.3(B).
 
mjc1060 said:
I was called to inspect a 100A 240V single phase residential service. In this panel attached to the bus where two lugs that had two more conductors feeding a second 100A panel. This second panel has no OCPD on the feeder conductors(these are 2' long). Both panels have 100A 2 pole main breakers. The service conductors from the meter are #3 and they feed the first panel. This seems to me a bad installation at best. Is this also a code violation and if it is where would I find it in the NEC?
Click to expand...

> This second panel has no OCPD on the feeder conductors

> Both panels have 100A 2 pole main breakers

Where do the feeder conductors go in the second panel if not to the main breaker?

In the first panel is the feeder tap after the service disconnect, on the bus feed by
the main breaker?
 
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