wire size on split parallels

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electricalist

electricalist

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dallas tx
Meter to 400 amp fused disconnect into bldg 24 x 24 j box to 225 amp rated mlo panel. In 24 x 24 are paralled 4/0 . That have nsi type connectors. 4 space.. 1 set feeds existing 225. So 225 / 230 amps. . I understand from meter to 1st disconnect thewire should be sized accordingly and can be split to multiple panels. Can this be done after the disconnect and Iif so will I need to use 4/0 to feed another panel from the nsi connectors or can idownsize if I use a main breaker new panel.20140926_105648.jpg
 
Couple of points:
Once you tap from your 4/0 (400 amp) circuit to any lesser ampacity you must comply with the 240.21 tap rules.
In that regard, the taps you have to your 225 amp panel must terminate as specified in 240.21. Both the tap rule and 408.36 require that your 225 amp panel be protected by a main over-current device sized by the panel and your tap.
The same will hold true for any other taps you add to your 4/0 feeders.

side notes:
(a)assuming the smaller conductors are equipment grounding conductors, 250.148 requires that you connect them to the j box also
(b) your grounding and grounded conductors need proper identification
(c) From you OP, it appears the panel shown is not a service panel therefore your grounded buss should not be bonded (green screw) to the panel
 
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Also, if that is a horizontally mounted panelboard with opposing breakers (left and right when mounted vertically), you cannot use any of lower spaces... the breaker handle would be up in the open position and down in the closed position. That would be a violation of 404.7.
 
Smart $ said:
Also, if that is a horizontally mounted panelboard with opposing breakers (left and right when mounted vertically), you cannot use any of lower spaces... the breaker handle would be up in the open position and down in the closed position. That would be a violation of 404.7.
Click to expand...

But it is apparently perfectly acceptable in Canada under the CEC. They have a lot more horizontally mounted panelboards there. :)
 
This is existing equipment in a warehouse/ office. The contractor had use look at adding to it. I agree that unless the fuses in the disconnect are 200 amp then this install is corrupt. I agree once feeders are split they will need ocp . My suggestion to my boss is add a panel horizontally above the j box. (Just kidding) to the right and feed it with 4 /0 to main breaker panel based on amps needed.. the price isnt much from 150 to 200. Either way keep the feeders at 400 amps then do our work , load calculation for the system and fuse the disconnect accordingly. Show the insp. And let him know what was existing
 
Smart $ said:
We must not be looking at the same picture... :happyno:
Click to expand...

Well... to use your words from an earlier thread....
"Well that's one viewpoint. Can you cite authoritative documentation that agrees?"
:D
Iwire and I may be laying down while viewing the picture in which case it is vertical.
 
augie47 said:
Well... to use your words from an earlier thread....
"Well that's one viewpoint. Can you cite authoritative documentation that agrees?"
:D
Iwire and I may be laying down while viewing the picture in which case it is vertical.
Click to expand...
Laying down while looking at the picture doesn't change the panel's orientation. But I do concede that the picture may not be oriented as viewed in real world... :p
 
hurk27 said:
Me too, there are two things in the photo that tells me that the left side of the photo is up, a red wire nut in the bottom of the panel and the studs, unless they glued the wire nut to the bottom of that panel and the studs are horizontal:p
Click to expand...
Good catch...
 
augie47 said:
side notes:
(a)assuming the smaller conductors are equipment grounding conductors, 250.148 requires that you connect them to the j box also
Click to expand...

If you look at what should be the top of the J box, you will see a large grounding bar that the three EGC's land on, one from each set of parallel conductors and one to the neutral bar in the ML panel,they are just not marked green at the termination.
 
hurk27 said:
If you look at what should be the top of the J box, you will see a large grounding bar that the three EGC's land on, one from each set of parallel conductors and one to the neutral bar in the ML panel,they are just not marked green at the termination.
Click to expand...

After looking at that bar it looks more like a 4X lug you would put on a buss like in a transformer, also looks like no paint was removed from behind it, and the attachment screw is not one that would be UL listed for a ground bar mounting??
 
fc495291cba00dd7c557fbdb9f6b8350.jpg
 
Man that took a minute to figure out. All of this is existing although I am keeping these corruptions in mind. I also found in the panel neutrals and grounds isolated yet I had ac guy check ahu and its electric heat as well. With #8 green as neutral in unit landed on grounding bar in panel. Why do yhey do this. Is it a easy way for them to say we got a neutral were good because to them they end up bonded anyway at the 1st disconnect
 
I think they should have sanded grounding mech. Lug in the j box. Some inspectors will tag it others are ok as long as the other bonds look good. The disconnect is factory set up to bond enclosure the holes we drilled for feeders to j box and panel and they ran a ground wire. Realistically they could have said the ridged nipples were the the egc
 
hurk27 said:
If you look at what should be the top of the J box, you will see a large grounding bar that the three EGC's land on, one from each set of parallel conductors and one to the neutral bar in the ML panel,they are just not marked green at the termination.
Click to expand...
Point made ! My aged eyes missed that.. saw the lug not the terminations
 
I missed it too. They were seperated to their respective type. Grounds left neutrals right. Although im there to know what I see. We do have someone that the person who did the work inspect it. Trivial sometimes. Helpfull sometimes
 
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