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#99182 - 07/28/06 01:50 PM Clearances  
bman  Offline
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Joined: Jul 2006
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Got a 75KVA 480V xfmr needing to go in a tight spot. Q- clearance in 110.26 151-600v . Got my xfmr sitting across an aisle from a branch panel, the top of xfmr housing is some distance lower elevation than the bottom of branch panel with nothing on wall below panel , therefore this would not be a condition 3?(exposed on both sides) I’m supposing the key phase in 110.26 (1) is "in the direction of live parts" Also is there anything to prohibit mounting a disconnect on side of Xfmr if disc is supplied by said xfmr and meets clearance requirements?


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#99183 - 07/31/06 04:33 AM Re: Clearances  
bman  Offline
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guess everbody lost their tape measures.


#99184 - 07/31/06 01:21 PM Re: Clearances  
gfretwell  Online Content


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Posts: 9,056
Estero,Fl,usa
It sounded like you answered your own question ... or maybe I didn't understand the question.


Greg Fretwell

#99185 - 07/31/06 02:08 PM Re: Clearances  
George Little  Offline
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Joined: Jan 2004
Posts: 1,489
Michigan USA
Okay bman- I've got my ruler by my side. What do you want me to measure???
Are we talking equipment that is required to be serviced while energized? In other words if you can turn the power of and service the transformer then the clearances of Table 110.26 don't apply. See 110.26(A)
How wide is the isle?
Did you maintain the distance specified by the manufacturer of the transformer?

The only question you've posed that I can see is- Can I mount the disconnect on the transformer? My answer would be probably so as long as it would not be on a panel that has to be removed for servicing the transformer and as long as it didn't block any ventilation holes for the transformer.


George Little

#99186 - 08/01/06 02:46 AM Re: Clearances  
bman  Offline
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Ok now were rollin. "likely to require", yep, that’s one of those phrases whose meaning changes with the AHJ mood for the particular day of the week. Always try and schedule inspection for Friday. Branch panel to me is a "likely", the xfmr ...naa, But AHJ strolls onto the job Monday morning after having shot crap on 18 holes yesterday afternoon and is gonna use me as his whippin boy, "No I don’t think so!" says he "What if you lose a phase, pop the front cover and hit the breaker to see if ya got a bad windin whilst juniors landin a #12thhn on that branch panel across the way! Haa, now you got yur self a condition 3!, move that tranny boy!" But I in my wisdom have received council from the boys at ECN, and point out that the branch panel is mounted above the horizontal plane that extends across the aisle from the top of the tranny housing so it is therefore not "in the direction of live parts" you see. Ah but wait, does "in the direction of" refer to a horizontal plane? or is it any plane, irregardless of direction? Now do you see my question?


#99187 - 08/01/06 06:59 PM Re: Clearances  
energy7  Offline
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Posts: 58
Oxnard, CA, USA
Isn't 110.26 about providing a safe working space? And it defines the height and width of the working space. Then the table defines the depth of the working space (not a portion of it).
This one's clear, to me. 480v. is 277v to ground, and condition 3. 4 feet clear from the bottom to the top of the working space.
By the way, we're all getting panic hardware on the exit doors of our 1200A+ rooms, right?


#99188 - 08/02/06 02:39 AM Re: Clearances  
bman  Offline
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Nope. Height only refers to "service equip., switchbds, panelbds, or MCC.


#99189 - 08/02/06 06:44 AM Re: Clearances  
George Little  Offline
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Joined: Jan 2004
Posts: 1,489
Michigan USA
bman- If I read correctly your original post said you were dealing with a panelboard:
Quote
Got a 75KVA 480V xfmr needing to go in a tight spot. Q- clearance in 110.26 151-600v . Got my xfmr sitting across an aisle from a branch panel, the top of xfmr housing is some distance lower elevation than the bottom of branch panel with nothing on wall below panel , therefore this would not be a condition 3?(exposed on both sides) I’m supposing the key phase in 110.26 (1) is "in the direction of live parts" Also is there anything to prohibit mounting a disconnect on side of Xfmr if disc is supplied by said xfmr and meets clearance requirements?
so the work space of the panelboard must be provided including the depth. The transformer only needs to have clearances specified by the manufacturer and is not required to meet 110.26. I would expect that there should be access to the transformer for servicing however.

[This message has been edited by George Little (edited 08-02-2006).]


George Little

#99190 - 08/02/06 11:20 AM Re: Clearances  
bman  Offline
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We'll leave it stand there.



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