Maximum allowable distance a two section panel board can be installed.

[debowceiphus]

I have a situation where I have to maintain safe working clearance in a new electrical room. I have a two section panel and was wondering if the sections had to be mounted together side by side or if they could be mounted separately on adjacent walls. The cans would be approximately four feet apart and connected by a 3.5 in. raceway at the top. The reason for this configuration is there are several conduits roughed in, in the slab and it would be rather difficult to change. I just finished a job where I had seen a similar installation but it was at least 40 years old.

 

[augie47]

I know of no restrictions on distance for the 2nd section. Maintain the proper conductor size and place as needed.

 

[texie]

I have a situation where I have to maintain safe working clearance in a new electrical room. I have a two section panel and was wondering if the sections had to be mounted together side by side or if they could be mounted separately on adjacent walls. The cans would be approximately four feet apart and connected by a 3.5 in. raceway at the top. The reason for this configuration is there are several conduits roughed in, in the slab and it would be rather difficult to change. I just finished a job where I had seen a similar installation but it was at least 40 years old.

Not a problem. The second panel can be anywhere. While not standard practice, it could even in another room.

 

[Smart $]

There is no distance requirement where feed-through conductor ampacity equals or exceeds the panel rating.

 

[m sleem]

There is no distance requirement where feed-through conductor ampacity equals or exceeds the panel rating.

If an OCPD is not required for the other section, can anyone show how will be the connection between these two sections, that of course would help.

 

[Smart $]

If an OCPD is not required for the other section, can anyone show how will be the connection between these two sections, that of course would help.

Typically wire jumpers from feed-through lugs (FTL) on first panel's bus at opposite end from MCB to bus lugs of second panel (MLO or [MLO/]FTL).

 

[infinity]

If an OCPD is not required for the other section, can anyone show how will be the connection between these two sections, that of course would help.

Here's a photo of a 400 amp feed-thru setup. Since every component is rated for 400 amps there would be no maximum distance restriction on the two panels.

 

[Ragin Cajun]

I have seen them on different floors of a dorm building. Still ok code wise if wire sizes are correct.

RC

 

[m sleem]

Here's a photo of a 400 amp feed-thru setup. Since every component is rated for 400 amps there would be no maximum distance restriction on the two panels.

Wow, very nice photo,

A question came to my mind, do we need to increase the wire size (feed thru) due to the voltage drop effect?

Thanks a bunch

 

[Ragin Cajun]

Now that we can have more than 42 ckts in a panel I expect the need for feed through may be less. But - the second panelboard does give more space to get conduits out! All depends.

Regarding wire size, the conductors to the second panel will see reduced load.


RC

 

[m sleem]

Now that we can have more than 42 ckts in a panel I expect the need for feed through may be less. But - the second panelboard does give more space to get conduits out! All depends.

Regarding wire size, the conductors to the second panel will see reduced load.


RC

So can not you see the need to increse the feed thru size when the main cable to breaker is increased due to the voltage drop?

 

[infinity]

So can not you see the need to increse the feed thru size when the main cable to breaker is increased due to the voltage drop?

It's not required by the NEC and since one componet of voltage drop wold be curent it's probably not necessary. The load current on the second panelboard would be only a portion of the entire load so even if the feeder had larger conductors sized for VD the feed through portion wouldn't need the same larger conductors.