Clarification on Detached Building

[Kenny Rigler]

Hey Guys-

I need some help on clarifying this one. Service comes down utility pole in the alley to the meter then to the disconnect directly below it. From the disconnect, it goes back up the pole, then overhead to the house about 100'. At the house it comes down the wall, to a "junction box" where it connects to the conductor that finally makes connects it to the panel in the house.

Is the 3-wire feeder okay in this situation? The house panel is still the distribution panel, right, and therefore would need the grounded and grounding conductors separated?

It doesn't appear to me that the distribution panel is bonded or grounded correctly, but wanted to make sure I communicated it correctly in the report. Thanks.

Kenny

[Kenny Rigler]

A few more of the inside panel...

[Jim Port]

The disconnect below the meter would be the service panel where the neutral would be bonded to ground. Any panel remote from this should have been a 4 wire feeder if any other metallic paths ran to the house like a phone, CATV line. Perhaps they were using the exception which allowed for a 3 wire feed and the re-bonding at the remote panel. If so they forgot the bond jumper.

I guess they do not have enough conduit to run into the top of the Cutler-Hammer panel?

[Joshua L. Frederick]

Originally Posted by Jim Port

Perhaps they were using the exception which allowed for a 3 wire feed and the re-bonding at the remote panel.

Can you elaborate on this?
So if there is 3 wires coming from the main service disconnect, the distribution panels don't have to follow the isolation & separation practices?

[Robert Meier]

Is there a total of 4 conductors in the over span to the house? It appears that they ran a separate EGC along with the 3 feeder conductors. There's no connectors on the NM cables entering the top of the panel. What year was this installed?

[Kenny Rigler]

Originally Posted by Jim Port

I guess they do not have enough conduit to run into the top of the Cutler-Hammer panel?

Hey Jim. The distribution panel service entered at the bottom of the panel not the top.

[Kenny Rigler]

Originally Posted by Robert Meier

Is there a total of 4 conductors in the over span to the house? It appears that they ran a separate EGC along with the 3 feeder conductors. There's no connectors on the NM cables entering the top of the panel. What year was this installed?

Hey Robert. There were only 3 wires from the service panel to the mast on the house. The other 2 wires you see connected below on the mast run to a tool shed. I haven't received the exact year on the house yet but I would say early 1980s.

[Robert Meier]

Originally Posted by krigler

Hey Robert. There were only 3 wires from the service panel to the mast on the house. The other 2 wires you see connected below on the mast run to a tool shed. I haven't received the exact year on the house yet but I would say early 1980s.

If this were installed prior to the 2008 NEC then a 3-wire feeder was permitted as long as there are no metallic common paths between the two structures. The neutral at the panel would be permitted to be bonded to the enclosure just like at a regular service. Each structure should have it's own grounding electrode system.

[Jim Port]

Robert, if you look in the one pic you can see they forgot the bond strap. It is just hanging loose on the screw.

[Jim Port]

Originally Posted by jfrederick

Can you elaborate on this?
So if there is 3 wires coming from the main service disconnect, the distribution panels don't have to follow the isolation & separation practices?

See RMs reply in post 8. With no other metallic paths between structures prior to the 2008 NEC you were allowed a 3 wire feeder and you again bonded neutrals and grounds the same as a service.

[Joshua L. Frederick]

Originally Posted by Jim Port

With no other metallic paths between structures

Metallic paths, such as??

Originally Posted by Jim Port

prior to the 2008 NEC you were allowed a 3 wire feeder and you again bonded neutrals and grounds the same as a service.

So before 2008 and if the distribution panel wires are only 3, then you don't have to isolate neutral and separate grounds & neutrals?
I am totally confused on this. Every post I see regarding distribution panels say that the isolation/separation applies & they must always follow this installation no matter how many wires.

[Robert Meier]

So prior to the 2008 NEC you could use the neutral for grounding a panel (bonding the neutral to the enclosure) in a remote structure providing a few conditions were met. One being that there is no parallel metallic paths between the two structures that would allow current to flow on it. In the 2008 and 2011 the new wording is an exception listed for existing installations only. Here's the wording in the NEC prior to the 2008:

Prior to 2008:

250.32(B) Grounded Systems For a grounded system at the separate building or structure, the connection to the grounding electrode and grounding or bonding of equipment, structures, or frames required to be grounded or bonded shall comply with either 250.32(B)(1) or (B)(2).
(1) Equipment Grounding Conductor.
An equipment grounding conductor as described in 250.118 shall be run with the supply conductors and connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
(2) Grounded Conductor. Where (1) an equipment grounding conductor is not run with the supply to the building or structure, (2) there are no continuous metallic paths bonded to the grounding system in each building or structure involved, and (3) ground-fault protection of equipment has not been installed on the supply side of the feeder(s),the grounded conductor run with the supply to the building or structure shall be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The size of the grounded conductor shall not be smaller than the larger of either of the following:
(1) That required by 220.61
(2) That required by 250.122

2008 NEC:

(B) Grounded Systems. For a grounded system at the separate building or structure, an equipment grounding conductor as described in 250.118 shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
Exception: For existing premises wiring systems only, the grounded conductor run with the supply to the building or structure shall be permitted to be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded where all the requirements of (1), (2), and (3) are met:
(1) An equipment grounding conductor is not run with the supply to the building or structure.
(2) There are no continuous metallic paths bonded to the grounding system in each building or structure involved.
(3) Ground-fault protection of equipment has not been installed on the supply side of the feeder(s).
Where the grounded conductor is used for grounding in accordance with the provision of this exception, the size of the grounded conductor shall not be smaller than the larger of either of the following:
(1) That required by 220.61
(2) That required by 250.122

Metallic paths could be a water pipe or phone line etc.

[Joe Funderburk, CMI]

http://www.nachi.org/forum/f19/3-wir...ildings-56130/

[Robert J. OConnor]

These posts have some information and diagrams concerning 3-wire and 4-wire remote panel feeders ...

http://www.nachi.org/forum/f19/overh...earance-61807/
http://www.nachi.org/forum/f19/suita...uipment-61984/

Also since that is a main lug only distribution panel, where is the SE rated main disconnect switch//breaker at the house? This should be present, in addition to the one on the pole below the meter. I see a smaller closed box on the outside of the house just before the feeder enters the building, but dont see a disconnect switch/breaker as it looks to just be a splice box.