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Joined: Jul 2001
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A little update, I asked the electrical instructor at the local tech college, who is very knowledgeable, and he said that because the panels are grouped together they are one service. He said it is in 230-70, which pretains to the six disconnect rule. I am unable to see how this applys, can anyone help? If these were both service panels (i.e. a double tub) then a case could be made for treating them as a single piece of equipment. However, you have stated that this second panel is a feeder from the first panel, because it has its own branch breaker in the main panel. The code says all panels after the service must have their N ang G separated. The code does not give any exception based on distance (or lack of it). You may be confusing the situation by calling this a sub-panel instead of a branch panel. In this part of the world a sub-panel is fed directly off the bus of the upstream panel instead of through a branch breaker.
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"In this part of the world a sub-panel is fed directly off the bus of the upstream panel instead of through a branch breaker."
Wouldn't that be a through fed panel? Isn't a subfed panel one where the tap is made ahead of the first panel's bus, normally at the main lugs or lugs of main breaker.
[This message has been edited by electure (edited 01-17-2007).]
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Generically a subfeed is one panel fed from an upstream panel without its own overcurrent protection (think conductors are subject to tap rules).
Other descriptions I use are:
Thru-feed - connected directly to the bus after the incoming main.
Sub-feed - connected directly to the incoming lugs
And one that is non-confroming:
Sub-feed breaker - a separate breaker connected to the bus but still mounted inside of panel.
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Word has it that the '08 code will require an EGC to all "sub panels" even when they are located ln a second building located on a property when fed from the main building Service. I guess that's a good thing. What do you think Greg? (gfretwell)
George Little
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I believe Ryan Jackson's proposal only removes the 3 wire exception to a sub in another building with no metallic paths.
I never had a problem with the old rule.
I get this conversation to refer to using the raceway for an EGC, that is still allowed to replace the grounded conductor (neutral). There is one main bonding jumper, in the service disconnect enclosure and it will never get bonded again on the load side.
I also read the "objectionable current on grounding conductors" rule to say you can't put neutral wires on a ground bus in a service panel if it is connected to the neutral bar via the main bonding jumper.
IE: you have the green screw in and you have a busbar screwed to the can. That is for grounding only. Otherwise you are putting circuit current through the bonding jumper.
Greg Fretwell
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So from this discussion it appears that there are now only two types of panels: Service-panels and sub-panels. It looks like I need to update my terminology from calling every thing simply a panel and then treating a service as a special case.
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The NEC doesn't recognize the term sub-panel.
You really just have the service disconnect and load side equipment. You can have load side equipment in the same enclosure as the service disconnect like in most residential load centers but it doesn't have to be. The main bonding jumper is always in the enclosure with the service disconnect tho.
Greg Fretwell
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JBD, you are correct. There are only panels (power panelboards or lighting and appliance branch circuit panelboards, see section 408.34).
Service equipment that is also a panel is a special case of one or the other (and such a panel board must be listed as service equipment).
Technically, service equipment ends at the main disconnect.
Bonding of the GEC is allowed to continue to the enclosure that contains the service disconnect. But, may be done anywhere from the weatherhead to the main disconnect enclosure.
All that is required is to bond the neutral to the GEC and the EGC, it is only a matter of our convenience that we use the same bus bar for both neutral and grounding conductors for our branch circuits.
Earl
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Well, the boss maintains that the installation will not have 5 conductors between them, But since he wanted a nipple between them I put a rigid nipple, with double locknuts. I will take a picture and send it to a moderator for posting and comment. Thanks to all, Gary
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Make sure that nipple is bonded well, it's going to be a current-carrying conductor if you hook it up like your boss insists. Remind him of that when he inspects it and asks why you slathered so much corrossion-inhbitor on it.
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