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#7181 01/25/02 09:58 AM
Joined: Jun 2001
Posts: 196
C
Cindy Offline OP
Member
why can't you use 3w seu with a separate 4awg egc from a service to a subpanel [with an isolated gc]? the egc shouldn't be current carrying so there shouldn't be a problem with impedance or inductive heating... that's why we keep them in the same 4w ser cable, right?

#7182 01/25/02 12:47 PM
Joined: Mar 2001
Posts: 2,056
R
Member
It isn't carrying current under normal conditions. However, in the event of a fault, the fault current may be limited by the reactance of the single conductor, if it is not in close proximity to the conductor feeding the fault. The OCPD might not open in such a case.

#7183 01/25/02 08:55 PM
Joined: Jun 2001
Posts: 196
C
Cindy Offline OP
Member
thank you redsy

#7184 01/25/02 10:34 PM
Joined: Dec 2001
Posts: 440
Likes: 3
Member
Miss Cindy,
If I may ask, where is the subpanel located?


The Watt Doctor
Altura Cogen
Channelview, TX
#7185 01/26/02 12:24 AM
Joined: Jun 2001
Posts: 196
C
Cindy Offline OP
Member
this was in a new house i walked through a few days ago, the meter and 200amp disconnect combo were surface mounted on the side of the garage, and the seu and 4awg cu were run across the garage in the joist bay above, and came down the wall to the 200amp loadcenter, with the isolated gc. it wasn't my job, and i didn't want to stir anything up, so didn't say anything to the contractor.... but i didn't think it was right. if i thought it was real dangerous then i would have said something, thats why i asked here, cause i wouldn't have been able to explain to him why it was a bad idea

#7186 01/26/02 10:54 AM
Joined: Aug 2001
Posts: 335
S
Member
This is 300-3(b)(1999) Notice it says 'and all EGCs'. I haven't seen your installation but it sounds like this would cover your situation.


(b) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, trench, cable, or cord, unless otherwise permitted in accordance with (1) through (4).

#7187 01/26/02 09:28 PM
Joined: Dec 2001
Posts: 270
E
Member
Aside from the code issue, it seems like a commonsensical thing to do,'til you get to the point of putting the wiring into the boxes. Doesn't seem likely that they could ever adequately close off the box opening, or adequately clamp the cable, with that extra conductor added to the cable. Of course, I'm sure UL hasn't tested such a set-up, so there's no way to be assured that the connection would work.

#7188 01/26/02 10:25 PM
Joined: Oct 2000
Posts: 4,116
Likes: 4
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Cindy,

Aside from other considerations, with SEU cable they don't have an insulated grounded (Neutral) conductor.

Bill


Bill
#7189 01/28/02 12:12 AM
Joined: Dec 2001
Posts: 440
Likes: 3
Member
Cindy,
Well, I will agree with Steve on this one. The reason that I asked the question above was to get a clear picture of the situation.


The Watt Doctor
Altura Cogen
Channelview, TX

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