How can I connect the main breaker to a sub-feed lugs panels?

[Gilf]

Hi,

This is the first time i am designing such a panel, and i am very confused. The first section of the panel will be used to feed the fire pumps only hence it is a MLO panel and I will need to install the breaker on section 2 so that there is not a secondary OPDC between the source and fire pump panel. The two sections of the panel are connected with sub-feed lugs. How do I connect the main breaker on this sub-feed panel?

 

[Gilf]

attaching a clearer image.

 

[Strathead]

Hi,

This is the first time i am designing such a panel, and i am very confused. The first section of the panel will be used to feed the fire pumps only hence it is a MLO panel and I will need to install the breaker on section 2 so that there is not a secondary OPDC between the source and fire pump panel. The two sections of the panel are connected with sub-feed lugs. How do I connect the main breaker on this sub-feed panel?

Two caveats, I am not an engineer and I can't blow up the attachment well enough to read it.

That said, I feel you are overthinking it. If you want you switchgear designed as a single entity then just draw it that way and let the switchgear manufacturer worry about it. If the utility metering is integral to the gear then they will put a separate pull section in with access to the buss. If it is not integral it can be as simple as providing extra lugs where the incoming parallel feeds land, to tap out to the fire pump.

A third option is that you can just run separate conduits from the source straight to the pump. For example, here in Florida, we put CT's in the Utility transformer, run feeders to the MDP and feeders to the fire pump straight from the stabs.

 

[Gilf]

Two caveats, I am not an engineer and I can't blow up the attachment well enough to read it.

That said, I feel you are overthinking it. If you want you switchgear designed as a single entity then just draw it that way and let the switchgear manufacturer worry about it. If the utility metering is integral to the gear then they will put a separate pull section in with access to the buss. If it is not integral it can be as simple as providing extra lugs where the incoming parallel feeds land, to tap out to the fire pump.

A third option is that you can just run separate conduits from the source straight to the pump. For example, here in Florida, we put CT's in the Utility transformer, run feeders to the MDP and feeders to the fire pump straight from the stabs.

So, if i just tap the incoming feeder from the transformer and connect to main circuit I'm done. I was just concerned that there are too many cables for a tap connection as the incoming feeder is 5 sets of (4x185) plus earth accordingly. May be I should use a tap connection ahead of the switchboard not in it then?

 

[dkidd]

You should look through Article 695, and these papers:

http://products.schneider-electric....ail&oid=09008926803d8747&cat=0b008926800ae93f
https://www.nema.org/Standards/Page...-Electric-Fire-Pump-Controllers.aspx#download

 

[Gilf]

You should look through Article 695, and these papers:

http://products.schneider-electric....ail&oid=09008926803d8747&cat=0b008926800ae93f
https://www.nema.org/Standards/Page...-Electric-Fire-Pump-Controllers.aspx#download

Thanks for the information. In this case, yes i am trying to tap ahead of the main service, however as there are many cables to be terminated from one main and one stand-by fire pump controller we decided to use section one of the switchboard as a distribution bus. This section would be a main lugs only panel. Hence, I would have a connection made ahead and not within the same enclosure. Section two will then be connected to this via sub-feed lugs. I just couldn't figure out how I would installed the main circuit of this multi-section panel in section two. Would the sub-feed lugs be connected to the main circuit breaker that is located in section two rather then section two's bus bar? Or would I need to tap the incoming service ahead of the switchboard and feed the main circuit breaker and the sub-feed lugs would just connect the two bus bars in the two sections? but then would i not have double feed into section two?

I think I'm getting even more confused as I read more and more

 

[Strathead]

So, if i just tap the incoming feeder from the transformer and connect to main circuit I'm done. I was just concerned that there are too many cables for a tap connection as the incoming feeder is 5 sets of (4x185) plus earth accordingly. May be I should use a tap connection ahead of the switchboard not in it then?

There are limits to the number of taps at the utility transformer and I believe they are set by the local utility. In the area I just recently had this discussion it was 8 connections. So in your case you would be OK. That is where you should start. Even then there are solutions. In the case I am citing we installed a tap box that had 30 connections. Brought in 8 and sent out 16. I think the box cost about $4,000

 

[Tony S]

Turkey comes under the IEC umbrella not the NEC so the rules for fire pump feeds differ.

The two red switches are off the incoming busbars, the incoming is isolated as you can see.