This one slipped by me. Situation: 200A Meter/Panel combo on post next to Xformer which is 100 feet from the house. They used to call that outdoor panel a "courtesy" disconnect. Not anymore. That is now the service so I need to run a ground wire. I'll burn up the last 2000ft I have of 3W 4/O URD and run a #4 cu with it. I'm guessing there's got to be a 4/O-4/O-2/O-#2 URD out there. Is there? Not to mention I'll need a 4W 250kcmil for my 200A heating panels. Rats!
4 wire URD
- Thread starter DPDT
- Start date
- Status
tryinghard
Senior Member
- Location
- California
DPDT said:
Sounds like a service disconnect, is the transformer utility owned?
What was the problem with the previous ?05 NEC code rule allowing the first disconnecting means to be at the building before requiring separation of the grounded and grounding conductors?
Was there evidence of a large body count or massive property damage from issues pertaining to this practice?
Does having the fourth wire from a remote disconnect to the building prevent me from having to ?voluntarily? bail out Wall Street with my tax dollars?
I?ve never really heard of any issues because of this.
Was there evidence of a large body count or massive property damage from issues pertaining to this practice?
Does having the fourth wire from a remote disconnect to the building prevent me from having to ?voluntarily? bail out Wall Street with my tax dollars?
I?ve never really heard of any issues because of this.
tryinghard
Senior Member
- Location
- California
KJay said:
I?m not sure if I?m following you but if the neutral is incorrectly bonded to equipment grounding this will enable a parallel neutral return path.
Bad ju-jues!
Nor have I. There must be something to it though. Just seems sort of ridiculous. Wonder what a 4/O URD 4W 1000' spool weighs
In answer to the other question, yes it is a poco xformer. After reading again today it seems a little unclear what to bond that EGC to. And do I take my #4cu from the rebar in the footing all the way out to the Disco? If someone could help me to understand this, it would be great.
In answer to the other question, yes it is a poco xformer. After reading again today it seems a little unclear what to bond that EGC to. And do I take my #4cu from the rebar in the footing all the way out to the Disco? If someone could help me to understand this, it would be great.
tryinghard
Senior Member
- Location
- California
DPDT said:
If the 200A Meter/Panel combo is the service disconnect (or first disconnect past the source) then the house requires an additional disconnect if it has more than six throws for circuits.
If this is your case and your permit is 08 you only common the neutral at the service disconnect. If this is your case and your permit is 05 or older you only have to keep separation if there is no other common conductive path from service to sub panel, no metallic water pipe, coaxial cable, phone line…Chack out 250.32(B)(2)
Last edited:
tryinghard
Senior Member
- Location
- California
KJay said:
Check out 250.24(A)(5), 250.142(B), & of course 250.30(A)(1)
tryinghard
Senior Member
- Location
- California
DPDT said:
The EGC and GEC and neutral (grounded conductor) are all common at the service disconnect because of the bonding jumper.
Past the service disconnect (downstream) the EGC remains separate from the neutral; it terminates to all panel enclosures and non current carrying items like case frames. The GEC terminates at the ground bus (not neutral).
Shorts are not trying to return to earth they are trying to return to source. If you have a short the fault path (effective ground fault path) will travel an intentional route to the service disconnect then on the neutral (grounded) conductor to source XO on the transformer. The bonding jumper completes the circuit for a ground fault.
Again if the neutral is incorrectly bonded downstream this will cause a parallel neutral return path, this current will not just travel the path of least resistance but all paths according to the level of resistance.
steelersman
Senior Member
- Location
- Lake Ridge, VA
depends on his AHJ and what code it's currently enforcing, based on his permit.tryinghard said:
tryinghard
Senior Member
- Location
- California
steelersman said:
Correct but if in doubt don't bond the neutral downstream.
tryinghard
Senior Member
- Location
- California
DPDT said:
At the service disconnect the neutral really has duel purpose 1) return path 2) ground fault path for shorts. Past the service disconnect these remain separate.
steelersman
Senior Member
- Location
- Lake Ridge, VA
when he says he has a meter/panel combo 100' away I take it he means a meter/disconnect, not a panel with OCPD's in it, right? Cause if it was a panel then all your branch circuit conductors would need to be run underground into your house and that would seem silly, but based on what I've learned here about some diffrerent types of installs depending on what part of the country you're in I wouldn't be too surprised.tryinghard said:
tryinghard
Senior Member
- Location
- California
steelersman said:
Correct, this would be the service disconnect.
Last edited:
tryinghard
Senior Member
- Location
- California
DPDT said:
Yes at each building (or structure). The purpose of the electrode connection to earth is explained in 250.4(A)(1).
SiddMartin
Senior Member
- Location
- PA
4/0 URD 4W is some big stuff, they come on 1000' reels that our bigger then my kitchen table. I think they call it Sweetbriar or Wakeforest, Wakeforest is the bigger one, that may be the 4W and Sweetbriar is a 3W I think. Thats all I got on the issue
tryinghard
Senior Member
- Location
- California
Maybe you can conduit more cost effectively?
frizbeedog
Senior Member
- Location
- Oregon
DPDT said:
There is. :smile:
Wrong pic, but it works. There is the one you describe available, except the ground is #4.
Manufactured by Southwire.
I don't know or have ever dealt with this company, but they have the stuff.
:smile:
- Status