No ground wire!

Status
Not open for further replies.
W

wondervamp

Member
Location
SF Bay Area
Occupation
Shop technician
Hello, this is my first post to this forum. I am a union apprentice. I am installing a new sub panel in a cottage behind the main house. This cottage has it's own main panel outside in the front of the main residence about 60 feet from the cottage. Whoever ran the feeders from the main to the sub panel inside the cottage ran it underground in PVC with no ground wire! It is only being fed with two hots and a neutral.

How do I ground this system? It will be very hard and almost impossible to pull a ground through the existing conduit from the main to the sub panel. There are water pipes and other systems in the ground alongside my electrical raceway. Am I correct in thinking I can drive a ground rod at the cottage and attaching a ground that way?

Please be as specific in details as possible. Also inform if I need to bond the neutral/ground at the sub panel in this case. As I know I should not do that in normal circumstances.

Thank you in advance.

wondervamp
 
I this was done under 2005 or prior code, it is legal as long as there are no other grounded metal paths between the outside disconnect structure and the house structure (hopefully that outside disconnet box is not connected to the water piping). This should fall under NEC 225 for feeders to detached structures.

You'd bond the panel at the house just like a service and sink two ground rods unless there is some other ground electrode available. Also be advised to you need a building disconnect that is Suitable for use as Service Equipment, so hopefully your panel has a main breaker. A main panel fed via a feeder to a detached structure is kind of weird -- has some Service rules and some subpanel rules.

If this is a new cottage, new feeder, and you're under 2008 code, then you have a problem.
 
suemarkp said:
I this was done under 2005 or prior code, it is legal as long as there are no other grounded metal paths between the outside disconnect structure and the house structure (hopefully that outside disconnet box is not connected to the water piping). This should fall under NEC 225 for feeders to detached structures.

You'd bond the panel at the house just like a service and sink two ground rods unless there is some other ground electrode available. Also be advised to you need a building disconnect that is Suitable for use as Service Equipment, so hopefully your panel has a main breaker. A main panel fed via a feeder to a detached structure is kind of weird -- has some Service rules and some subpanel rules.

If this is a new cottage, new feeder, and you're under 2008 code, then you have a problem.
Click to expand...


You're right except, you need the rods whether or not there are other pipes there.
 
mcclary's electrical said:
You're right except, you need the rods whether or not there are other pipes there.
Click to expand...

The NEC never specifically requires rods, any electrode will be OK.

If there happens to be a water pipe that qualifies as an electrode we would have to use it and provide a supplemental electrode of any type to that.
 
iwire said:
The NEC never specifically requires rods, any electrode will be OK.

If there happens to be a water pipe that qualifies as an electrode we would have to use it and provide a supplemental electrode of any type to that.
Click to expand...


You're right, but the "supplemental electrode" is usually rods. I see what you're saying though.
 
RE: No Ground Wire!

RE: No Ground Wire!

Thanks guys for your responses! However, I guess I need to be a little more specific as to my situation and hopefully will be able to convey that below:

Ok, There are two structures on the property. One is the main house with it's main panel outside attached on the side of the house. The other structure is a 400 sq. ft. cottage on the same property in the backyard about 40 feet back.
Both structures are independent of one another, meaning that that have separate meters but share PG&E's drop so when the utility bill comes, each structure gets their own separate bill. These main panels are right next to each other in the front of the main house. They both have main breakers that are used as a disconnecting means.

Whoever ran the service for the cottage in the back ran two hots and one neutral underground in PVC WITHOUT a ground wire. The main panel for this cottage in the front of the MAIN house has no ground wire in the panel, therefore there is no BONDING of the ground/neutral bars in this main panel. ALSO, the main panel for this cottage is not grounded to earth with a ground rod or uffer. So there is NO GROUNDING, except for where this genius decided to tie the branch circuit grounds together at the sub panel inside the cottage.

So to be CLEAR, there are no ground rods in the front main panel or in the back for the sub panel which is supplying the cottage indoors. As I stated earlier, there are other systems running through the ground near the cottage feeders (the plumbing runs beside the cottage feeders).

Where do I pound rods? Which panels get bonded neutral/ground. Do I pound rod in the front at the main and bond the main panel which is currently without rod and bonding situation, or just pound rod in the backyard next to cottage and bond neutral/ground in sub panel, or BOTH.

Thanks,

Wondervamp
 
wondervamp said:
Whoever ran the service for the cottage in the back ran two hots and one neutral underground in PVC WITHOUT a ground wire.
Click to expand...

And THIS CAN BE fine if the rules where in 250.32(B)(2) where followed.

The main panel for this cottage in the front of the MAIN house has no ground wire in the panel, therefore there is no BONDING of the ground/neutral bars in this main panel.
Click to expand...

Where is the service disconnect for this main house?



ALSO, the main panel for this cottage is not grounded to earth with a ground rod or uffer. So there is NO GROUNDING,
Click to expand...

Start using the right terms.

EGC, GEC, bonding etc, it is very difficult to tell what you mean when you just say 'grounding'.


except for where this genius decided to tie the branch circuit grounds together at the sub panel inside the cottage.
Click to expand...

That would be correct with just a three wire feeder.

So to be CLEAR, there are no ground rods in the front main panel or in the back for the sub panel which is supplying the cottage indoors. As I stated earlier, there are other systems running through the ground near the cottage feeders (the plumbing runs beside the cottage feeders).

Where do I pound rods? Which panels get bonded neutral/ground. Do I pound rod in the front at the main and bond the main panel which is currently without rod and bonding situation, or just pound rod in the backyard next to cottage and bond neutral/ground in sub panel, or BOTH.
Click to expand...

Your not going to like this but I think this has to be said, you do not appear to have the experience to do this job without some on site help.

You say your a union apprentice, what type of work do you normally do?

Commercial, industrial?
 
wondervamp said:
Thanks guys for your responses! However, I guess I need to be a little more specific as to my situation and hopefully will be able to convey that below:

Ok, There are two structures on the property. One is the main house with it's main panel outside attached on the side of the house. The other structure is a 400 sq. ft. cottage on the same property in the backyard about 40 feet back.
Both structures are independent of one another, meaning that that have separate meters but share PG&E's drop so when the utility bill comes, each structure gets their own separate bill. These main panels are right next to each other in the front of the main house. They both have main breakers that are used as a disconnecting means.

Whoever ran the service for the cottage in the back ran two hots and one neutral underground in PVC WITHOUT a ground wire. The main panel for this cottage in the front of the MAIN house has no ground wire in the panel, therefore there is no BONDING of the ground/neutral bars in this main panel. ALSO, the main panel for this cottage is not grounded to earth with a ground rod or uffer. So there is NO GROUNDING, except for where this genius decided to tie the branch circuit grounds together at the sub panel inside the cottage.

So to be CLEAR, there are no ground rods in the front main panel or in the back for the sub panel which is supplying the cottage indoors. As I stated earlier, there are other systems running through the ground near the cottage feeders (the plumbing runs beside the cottage feeders).

Where do I pound rods? Which panels get bonded neutral/ground. Do I pound rod in the front at the main and bond the main panel which is currently without rod and bonding situation, or just pound rod in the backyard next to cottage and bond neutral/ground in sub panel, or BOTH.

Thanks,

Wondervamp
Click to expand...


The bond will take place at the service panel.
When at subpanel, rods come to can/ground bar.
 
RE: No Ground Wire!

RE: No Ground Wire!

Uh Bob,

Your right I do not have any RESIDENTIAL experience because as Union Electrician's, we do about 90% commercial, industrial work and as an apprentice I have not obviously had as much experience as you. We do practice using the code book in school, however, as you well may know the code book is like reading hieroglyphics sometimes and I thought I might get some quick brotherly advice on this site so I didn't have to spend all day researching the code book on the RIGHT way to do this.

Commercial electrical and residential electrical is like comparing apples to oranges!

However, it is not rocket science and I do have other friendly resources of advice. I clearly stated that the main's for the two structures were outside in the front of the main house serving as the disconnecting means.

Wvamp
 
wondervamp said:
Commercial electrical and residential electrical is like comparing apples to oranges!
Click to expand...

Wvamp, easy now this site really is the best place to dialog about our trade. :) The safe use of electricity is the same regardless of application. You?re questioning an item that confuses many in the trade. Best advise I can give on this specific topic is don't allow parallel returning current - at all! Contain all returning current on an intentional conductor and nothing else ? ever - regardless of commercial, industrial, or residential.
 
wondervamp said:
As I stated earlier, there are other systems running through the ground near the cottage feeders (the plumbing runs beside the cottage feeders).
Click to expand...
If any of these systems are metallic, such as metal water or sewage, or other wiring, such as cable or phone, you're not okay even pre-2005. Could be an issue, but it has worked all these years. ;)

The grounding at the house and at the cottage would each be done just like a service. The electrodes at both places are okay, since the earth isn't considered to be a parallel conductive pathway.
 
tryinghard said:
Wvamp, easy now this site really is the best place to dialog about our trade. :)
Click to expand...
That's true. You can be assured of receiving a wide variety of opinions here.

Our collective motto should be "Not always right, but never in doubt!" :grin:
 
wondervamp said:
Uh Bob,

Commercial electrical and residential electrical is like comparing apples to oranges!


Wvamp
Click to expand...

Not really, if you were wiring houses in Chicago you would be running emt and regardless, the rules for grounding and bonding of services is the same for all.


Roger
 
Re: no ground wire

Re: no ground wire

Apples to oranges in the way that as a union elctrician we are mostly bending EMT all day and mostly spend our day as mechanics installing EMT and the supporting means for our raceways, building electrical rooms etc.
Then we pull wire through these systems. All I'm saying is that In the 5 years as an apprentice we may not ever get any residential experience. If so, maybe 3 mos. Got my answers from the code book after all. Thanks
 
Status
Not open for further replies.
Top