pattenp
Well-known member
The NEC four wire requirement is for branch feeders after the service disconnecting means, not the service conductors. So what the power company does is a mute point.
Do I need a ground rod at the shop?
- Thread starter Atcnick
- Start date
The NEC four wire requirement is for branch feeders after the service disconnecting means, not the service conductors. So what the power company does is a mute point.
I understand the rules and why they are there, just trying to put things into perspective.
There will always be problems with neutral current on metal lines between houses and buildings. There is only so much we as electricians can do about it unless the utility starts running 4 wire from the transformer, which I doubt will ever happen.
This thread is going downhill, I doubt the OP knows which direction to go after all this...
Your right this guy was a hack. I doubt most amateurs have a clue WHY they need to do these things though, other than some guy on the internet told me to. That's what I would expect out of a pro.
wyliesdiesels
Well-known member
The correct way to wire it up and the direction he should go has been said by several people...
Yes it has and I'm not saying my suggestion was "correct". All the **** on the second page is a lot to sift through.
outdoorspace
Banned
- Joined
- Jan 28, 2014
- Messages
- 356
Lolno need to spell it for me. I understand it perfectly.
It doesnt come directly from the meter base. It comes from the disconnect which is the service equipment.
Ugh... Right now the wire is not hooked to anything! What I am saying is that if the wire were connected to the meter base (and not the disconnect) then it would comply with current code. You must understand this? You keep disagreeing with an argument that I am not making; you might not even realize it but you are acting out a "straw man fallacy."
Look, there is no inspection. I think we've all established that a separate ground is a better idea. I would certainly say a separate ground is necessary if there are other wires connecting the buildings. But in reality there will be no problems if the ground wire is left out. Do you have a single example of when you have seen that this is an actual problem? Anyone?
wyliesdiesels
Well-known member
Except you did not explain as much in your previous comment.
Regardless, having that much unfused wire is not a good idea...
And the absence of an inspection doesnt matter if the AHJ or fire department requires disconnects...
Also, i will reiterate that the Op needs to address the bonding issue on the subpanel in the house...
wyliesdiesels
Well-known member
Every single AHJ has different rules.
You could call your county building department and ask them.
Back to the original question, "Do I need a ground rod at the shop?". I have almost an identical situation with a 400a service split in 2 200a services for my house and shop except it appears to be wired correctly with 4 conductors going to my shop with neutral & grnd seperated and the same in the house. I only have one ground rod at the house, none at the shop. The shop is about 150' from the house. Do I need a ground rod at the shop? Would it be be beneficial?
wyliesdiesels
Well-known member
alfredeneuman
Well-known member
That is unless you can prove that is 25 ohms or less to ground...and the test equipment price for buying or even renting the equipment is mega$$ so in essence you need to drive 2 of them, unless you enjoy wasting money to prove a point.
sberry
Banned
Lightning strikes to a neutral can't be a good idea. I got no idea how many actual problems it causes but have seen current flow where there should be none. I can't believe they went to all the trouble world wide just on a brain fart, included it in national codes of several similar countries.
I like to fancy myself as having a little,,, rudimentary understanding of how and why this works and when I visualize the system that looks like a tree and a spiderweb depending on my perspective it makes sense.
The other half of grounding,, the rest of the story is insulated current carring conductors which include neutral or maybe more acurately grounded conductors.
wyliesdiesels
Well-known member
bmwpowere36m3
Well-known member
- Joined
- Nov 8, 2012
- Messages
- 1,125
When doing my father's shop I was under the impression to separate the neutral and ground [at shop panel feeding off home main panel] and install two ground rods... turns out the AHJ didn't want it (something about lightning). I forget how is corrected it, but he abandoned the rods at the shop.
^^^^^^^That seems like what I saw 10+ years ago when it was wired and it did not get a separate ground rod. I didnt worry to much about it since there was no other "conductors" back to the house. But I recently ran a Cat6 cable and a coax TV cable to the shop from the house and thought I should check in to it.
wyliesdiesels
Well-known member
*sigh* more confusion added to the mix
Lightning and bonding of neutral are different issues that have nothing to do with each other. Same with bonding of neutral and grounding electrodes. The 2 have nothing to do with each other.
Unless your AHJ was under pre2008 code cycle, an isolated neutral was required.
And grounding electrodes have been required for many decades...grounding electrodes are for grounding lightning and isolated neutral is for keeping current from flowing on pathways that it shouldnt be flowing on....
2 separate issues here....
Separate ground rods were required 10 plus years ago...theyve been required long before that.
The presence or absence of "other conductors" has nothing to do with ground rods being required.
again 2 separate issues here.
Grounding electrodes are required even if "there are no other conductors" as you put it. Grounding electrodes are for grounding lightning.
Since you have other electrical pathways running out to the detached structure you need to make sure you have an isolated neutral in your subpanel and a 4-wire feeder in addition to ground rods...
Lightning and bonding of neutral are different issues that have nothing to do with each other. Same with bonding of neutral and grounding electrodes. The 2 have nothing to do with each other.
Unless your AHJ was under pre2008 code cycle, an isolated neutral was required.
And grounding electrodes have been required for many decades...grounding electrodes are for grounding lightning and isolated neutral is for keeping current from flowing on pathways that it shouldnt be flowing on....
2 separate issues here....
Separate ground rods were required 10 plus years ago...theyve been required long before that.
The presence or absence of "other conductors" has nothing to do with ground rods being required.
again 2 separate issues here.
Grounding electrodes are required even if "there are no other conductors" as you put it. Grounding electrodes are for grounding lightning.
Since you have other electrical pathways running out to the detached structure you need to make sure you have an isolated neutral in your subpanel and a 4-wire feeder in addition to ground rods...
bmwpowere36m3
Well-known member
- Joined
- Nov 8, 2012
- Messages
- 1,125
I guess my point was check with your local AHJ first... I thought I was being "smarter" and he didn't approve. Now I'm curious, but I believe we only ran a 3 conductor wire out to the shop... so the neutral/ground must be connected and relying on the grounding rods at the house.
He did make a comment regarding lighting and NOT having separate grounding rods at the detached structure... who knows.
sberry
Banned
It needs rods. You want the neutral or any wire to carry a strike back to the main??? No, ideally it would be sent to the rods at the first point. This isn't so thing new, there is a right way to do it. An inspector should know it.
Last edited:
ard
Well-known member
OP-
Somewhere above you commented about 'its all buried'... but it sounds like you have conduit with individual conductors- GOOD NEWS. If there is enough room, pull the 3 wires out, add a ground wire (this can be TWO sizes smalller, IIRC) and pull them back into place. No digging.
IMO, even if something doesnt require inspection, the work still needs to meet code. Just because a county has no inspections, it is no excuse for builders and their subcontractors to do ****.
Also, be careful with your builder. If he is like most, he is trying to cover his a$$. While he may sound like he is on your side, if the electrician is his sub, he is almost surely conflicted. Make sure your inspector is working for you.
and yeah, two rods out at the shop. Thats gonna be the easiest part of this!
Somewhere above you commented about 'its all buried'... but it sounds like you have conduit with individual conductors- GOOD NEWS. If there is enough room, pull the 3 wires out, add a ground wire (this can be TWO sizes smalller, IIRC) and pull them back into place. No digging.
IMO, even if something doesnt require inspection, the work still needs to meet code. Just because a county has no inspections, it is no excuse for builders and their subcontractors to do ****.
Also, be careful with your builder. If he is like most, he is trying to cover his a$$. While he may sound like he is on your side, if the electrician is his sub, he is almost surely conflicted. Make sure your inspector is working for you.
and yeah, two rods out at the shop. Thats gonna be the easiest part of this!
wyliesdiesels
Well-known member
There is no need to ask the AHJ as the NEC is very clear on how to do this.
4-wire with isolated neutral and grounding electrodes....
And he didn't approve what?
And as said by Sberry, you dont want a lightning strike traveling back to your main in search of a path to earth.
This is why every building needs grounding electrodes.
If the inspector from your AHJ told you otherwise, then he doesnt know basic concepts nor code and needs to take some classes....
I definitely have 4 conductors to my shop with separated/isolated grounds and neutrals in the shop panel. Same in my house panel. How many actual ground rods do I need at the shop? And at the house? The house was built in 1981 and only has one. I see ard says "two rods at the shop"
Was the shop built then also? If yes, it predates the the requirement and is fine.
Do you know which edition of the NEC was in effect when it was built?
No I sure dont. I am not necessarily looking to "beat" the code, but more interested in what the correct method is. If adding 1 ground rod at the shop is sufficient and will improve the safety factor then thats what I will do. If there is an added benefit to having 2 I will consider that as well. Thanks
acer66
Well-known member
As said before, you can get away with one but you would need expensive equipment to verify that it meets the code requirment, that is why most people, myself included, just put two spaced at least 6’ apart in.
sberry
Banned
Where are you? Some places you can pound a rod in standing water and some so dry they probably don't do much. Lots of them in the world with a single rod,,, more is better and cant hurt.
ard
Well-known member
So no matter the voltage drop or distance, #4 is always good for a ground on a 200A sub?
(and I qualified it IIRC for a reason!
)alfredeneuman
Well-known member
If the conductor sizes are increased for the voltage drop, the ground need to be as well