Metered and unmetered conductors

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hvelghe

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My company as well as many others that I have researched on the internet does not allow metered and unmetered conductors in a common raceway. I have been asked several times why that is. I can find nothing very definitive in either the NEC or NESC to explain the reason for the policy. I don't like having to tell people "I don't know why, that's just our policy." Anyone ever dealt with this?
 
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You won't find anything in the NEC that addresses "Metered and Unmetered" conductors in a common raceway, but you will find where "Service Conuductors" as in "Unfused" can not be in a raceway with any other coductors as in "Fused".

230.7 Other Conductors in Raceway or Cable
Conductors other than service conductors shall not be installed in the same service raceway or service cable.

Exception No. 1: Grounding conductors and bonding jumpers.

Exception No. 2: Load management control conductors having overcurrent protection.
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Roger
 
hvelghe said:
My company as well as many others that I have researched on the internet does not allow metered and unmetered conductors in a common raceway. I have been asked several times why that is. I can find nothing very definitive in either the NEC or NESC to explain the reason for the policy. I don't like having to tell people "I don't know why, that's just our policy." Anyone ever dealt with this?
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I've seen many examples of unfused/fused in the same raceway. I'll see if I can dig up a picture I have of a local convenience store that has a 400 ampere riser terminating in an outdoor meter channel and the load-side meter channel conductors (still service conductors) going in conduit into a trough and thru the trough to emerge out the far end to a 400 ampere fused main service disconnect. Then, from the disconnect, the now-called Feeders return to the trough, and lay up against the service conductors within the trough before going out in conduits to mlo panelboards within the store. This condition would allow a bypass of the ocpd device entirely if a connection was made (by the insulation failing or some other accident) between the service conductors and feeders within the same trough. :) Not a good hook-up at all. I even brought it to the poco's attention and they did nothing....:confused:
 
Funny you should ask. For the past few days I've been reading the various "green books" for the different PoCo's here in New England and some of them prohibit unmetered power sharing the same raceway/trough/enclosure as metered power.

The bottom line is that you need to consult your "Green Book" from your local PoCo.
 
peter d said:
Funny you should ask. For the past few days I've been reading the various "green books" for the different PoCo's here in New England and some of them prohibit unmetered power sharing the same raceway/trough/enclosure as metered power.

The bottom line is that you need to consult your "Green Book" from your local PoCo.
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The local poco here prohibits it in their "Green Book", too, but they don't enforce it when push comes to shove. :mad:
 
roger said:
. . . but you will find where "Service Conuductors" as in "Unfused" can not be in a raceway with any other coductors as in "Fused".
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Doesn't this happen in every main-breaker panel?
 
LarryFine said:
Doesn't this happen in every main-breaker panel?
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Yes it does, but that is not prohibited.

Take note of the wording in the article, it doesn't prohibit fused and unfused wires in a cabinet, box, or panel, only raceways and cables.

Roger
 
roger said:
Yes it does, but that is not prohibited.

Take note of the wording in the article, it doesn't prohibit fused and unfused wires in a cabinet, box, or panel, only raceways and cables.
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Then why can I not feed panel B through panel A?

I am doing a service with a 1-ph 200a MB panel (A) and a 3-ph 125a ML panel (B). The service is a 200a 3-ph, 4-wire hi-leg Delta. The only load on the 3-ph panel is the existing roof-top AC unit. I will use two 3/0's for the 200a with a 1/0 neutral, and three #4's for panel B.

When I wanted to feed panel B by tapping A and C phases from the conductors supplying panel A in that panel, and running the hi-leg straight through panel A unbroken, I was told that the tapping was okay, but the unbroken conductor could not pass through the MB panel.

I had intended to nipple the two panels together, but I was told that it is not permissable to use a panel as a raceway for service conductors. The only solution was to either double-lug the meter (not allowed by POCO in less than a 320a meter) or use a trough/gutter/box to make joints in.


Added: The load demands are 117a for panel A and 18a for panel B. This is a retail space.
 
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Larry, it sounds as though you need to ask whoever told you you can't do this to show you where this is prohibited.

Personally, I would build a gutter service for this installation.

Roger
 
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