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Author Topic: Subpanel disconnect?  (Read 4165 times)

frank kayser

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Re: Subpanel disconnect?
« Reply #10 on: February 09, 2017, 06:26:33 pm »

You have me going, describing this service as 220v and then as 3 phase.  220v is not a typically specified voltage for either split phase or 3 phase services.

A 3 phase Delta service would have no neutral (unless it's a "high leg" delta or corner-tapped delta service).  Motor loads, resistance heaters, etc need no neutral.  It sounds like that's the kind of applications intended for this new service in the cafe.

I take it this is a non-profit venture that somehow thinks kluging together such things is acceptable?  No permit or inspections?  OY VEY.  After what you found (open hot wires) the board should be petrified of the potential for a fire or personal injury lawsuit and be more concerned about getting it fixed legal and right.  Saving money doesn't help when the building burns down or the dish washing person is electrocuted.


I'm having a deja vu moment here... I think I posted almost those same, exact words in this forum a few months ago....


Trust me.  When you, Stephen, and TJ talk about electric, I treat it as gospel.  Most of this is beyond my current understanding and experience. 


Tim, if you think for a moment I do not know what I'm talking about, then you're absolutely correct.  I'm clueless, but sometimes I can spot someone more clueless than I.
What I KNOW for SURE: we have three 100amp three phase main panels. (expanded into separate storefronts)
The new subpanel was described as a "220 only" panel, whatever that is.  I'm too ignorant to know, but it sounded... off.  It sounded to me like "don't worry your pretty little head - us professionals know best".  Couldn't have been talking to me, cause no one will accuse me of having a "pretty little...anything"


Again, you're also absolutely correct:  this is not a 501(c) (3) organization, but they do consider themselves non-profit.  Most of the work until now has been non-permit (poor quality) kludging.  This subpanel was put in by a licensed electrician, though, and it was after that work and rewiring the dishwasher when the live 220 showed up under the sink.  That's what scares me to death.  What else did he miss?


I think my electrician and I have the attention of most of the board.  We're meeting with my electrician for expanding, properly, with permitted, inspected work by a master electrician with commercial experience.  Tomorrow will be a requirements meeting.  We have a builder with his own business on the board that has done a lot, but also thinks he can do it all, and being a board member, throws his weight around a bit.  Getting him to back down on anything is a major issue right now.  Management is phrasing this as "well, we need a backup electrician in the case the other is too busy".  So his guy is not being replaced, just a second, just in case.  That appeases the builder.


As I said, not on my agenda to kill anyone.  This has to be right. 


Again, thank you all.


frank



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Jonathan Johnson

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Re: Subpanel disconnect?
« Reply #11 on: February 09, 2017, 07:54:49 pm »

DISCLAIMER: I'm not an electrician. I'll defer to those who are.

Service entrances (where electricity enters the building) and subpanels have different rules w/ respect to disconnects and grounding.

The length of unfused wire -- no upstream OCPD -- between where it enters the building and service disconnect is limited (I'm not sure what that limit is). And I think the service disconnect is limited to "6 handles" -- but I don't remember if that's in total, or per service entrance panel. So you could have a service entrance panel with no "main" breaker but up to 6 single- or double-pole breakers -- that don't add up to more than the current capacity of the incoming wire. Practically, I would think that this would eliminate a panel with more than 12 spaces, as someone could add breakers so there's more than 6 handles. (Sure, they *could* use duplex breakers and get more, but if the panel already has 6 standard double-pole breakers, it's full and not easy to add more.)

As long as there's an upstream overcurrent protective device (OCPD) acting as the service entrance or in another upstream subpanel, you don't need a "main" breaker in a subpanel, and the subpanel isn't limited to 6 handles.

As for grounding, the neutral and ground can only be bonded in the service entrance. Also at the service entrance will be a Grounding Electrode Conductor (GEC) that leads to the grounding electrode system, which may include ground rods, rebar in concrete, building steel, piping, an intersystem bonding point (where CATV, phone, etc. tie in to the grounding system),etc. The GEC is supposed to be continuous (no splices) between the service entrance and each ground rod or bonding point.

Any subpanels have to have neutral and ground isolated, which implies that you'll have to run separate neutral and ground (Equipment Grounding Conductor, EGC) wires. In the subpanel, the neutral busbar cannot be jumpered to the grounding busbar, or bonded to the cabinet. The cabinet must be bonded in some manner to the EGC -- possibly to the grounding busbar. Some jurisdictions may allow metallic conduit between the service entrance and the subpanel, but it's safer practice to leave the conduit a "passive" ground and have a separate EGC in the conduit to bond your panels.

In the case of a subpanel with no neutral, if it's equipped with both neutral and grounding busbars, they could both be utilized as grounding busbars if they are properly bonded. The panel should be clearly labeled as having no neutral.

If the subpanel is in an outbuilding protected by an OCPD in the primary building, it could must be treated as either a subpanel grounded through the panel in the main building and having separate neutral and grounding conductors, OR it could be treated as another service entrance, in which case it can and it could have a "main" breaker, a neutral/ground bond, and it must have its own EGC leading to its own grounding system. (Edited; thanks to Stephen Swaffer. I hope I made those edits correctly.)

A service entrance could consist of a panel with a single "main" breaker, and the ground and neutral are bonded in this panel (with the appropriate GEC to a ground rod), and a feeder with both neutral and ground goes to a subpanel which includes breakers for all of the branch circuits. Other systems (plumbing, structural steel, telephone, etc.) may be bonded in the subpanel rather than the service entrance. This is how manufactured homes and modular buildings are typically wired; the service entrance is in a pedestal or pole outside and not attached to the building. The panel in the building is effectively a subpanel, and neutral and ground aren't bonded there.

I don't know if that sheds any light onto your question or if I just took you down an irrelevant rabbit trail! That's my understanding, anyway. It's worth every penny you paid for it.
« Last Edit: February 10, 2017, 01:25:04 pm by Jonathan Johnson »
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Jonathan Johnson

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Re: Subpanel disconnect?
« Reply #12 on: February 09, 2017, 07:57:45 pm »

Question: is it true that according to the NEC, if a breaker is installed so the handle moves vertically, OFF must be DOWN?
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Stephen Swaffer

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Re: Subpanel disconnect?
« Reply #13 on: February 09, 2017, 10:16:31 pm »


If the subpanel is in an outbuilding protected by an OCPD in the primary building, it could be treated as either a subpanel grounded through the panel in the main building and having separate neutral and grounding conductors, OR it could be treated as another service entrance, in which case it can have a "main" breaker, a neutral/ground bond, and its own EGC leading to its own grounding system.


Code defines "service" as equipment coming from the serving utility-so it is really not up to the electrician to define how you treat it.  If it is a subpanel, it is a "feeder" and as such must have a seperate neutral and ground.  250.52 also requires a building supplied by a feeder or branch circuit to have its own grounding electrode system.

Yes, down must be off for circuit breakers  NEC 240.81  This was not always so-you will occasionally find an old panel where one row of breakers is "upside" down.
« Last Edit: February 10, 2017, 08:06:29 pm by Stephen Swaffer »
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Steve Swaffer

Jonathan Johnson

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Re: Subpanel disconnect?
« Reply #14 on: February 10, 2017, 01:26:22 pm »

Code defines "service" as equipment coming from the serving utility-so it is really not up to the electrician to define how you treat it.  If it is a supanel, it is a "feeder" and as such must have a seperate neutral and ground.  250.52 also requires a building supplied by a feeder or branch circuit to have its own grounding electrode system.

Yes, down must be off for circuit breakers  NEC 240.81  This was not always so-you will occasionally find an old panel where one row of breakers is "upside" down.

Thanks for the corrections and clarifications!
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ProSoundWeb Community

Re: Subpanel disconnect?
« Reply #14 on: February 10, 2017, 01:26:22 pm »


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