I had a red iron building built back earlier this year. Looked at getting some of the electrical done and was wondering about grounds. The building has a 4 wire feeder ran to an inside panel at the shop. It is fed from the house that has two ground rods to my service up there. I know there needs to be two ground rods placed at the shop, but what about the building itself? Should it be ran to same ground rods or have a bare ground ran from it to a separate set of grounds rods? Or will it be tied back to the panel? Little lost here and just want to make sure it's done right. Thanks for your help.
Grounding building
- Thread starter Jwbfx4
- Start date
sberry
Banned
It should have an available connection to rebar in the footer. But, the building should be connected to the ground bar = to the ground wire back to the panel or better and a couple rods wont hurt and can act as backup to any other uffer, underground steel lines etc.
FWIW, a mobile or mod home with steel frame is an example, needs a ground bond to the frame with a visible connection. 6 for 200 and 8 for 100 and there may even be a couple circumstances for number 4 to electrodes.
My panels are entrance, at the neutral main have a scrap of 2 to lug bonding them to the steel.
All the grounds will be connected to the 4th wire back to service main. Neutrals (whites) will be insulated conductors. Everything metal, the floor to some extent, all equipment should be tied together via 4 wire as to be at the same potential. No difference between a grounded tool you are holding and the frame of the building all hooked together as 1.
No potential difference and any fault or short to itself or ungrounded conductors goes to service main.
FWIW, a mobile or mod home with steel frame is an example, needs a ground bond to the frame with a visible connection. 6 for 200 and 8 for 100 and there may even be a couple circumstances for number 4 to electrodes.
My panels are entrance, at the neutral main have a scrap of 2 to lug bonding them to the steel.
All the grounds will be connected to the 4th wire back to service main. Neutrals (whites) will be insulated conductors. Everything metal, the floor to some extent, all equipment should be tied together via 4 wire as to be at the same potential. No difference between a grounded tool you are holding and the frame of the building all hooked together as 1.
No potential difference and any fault or short to itself or ungrounded conductors goes to service main.
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Thanks. I'm in the county so not inspected, but want it done right. Just trying to make sure it gets done the right way. When the concrete guys poured I was absent, and they didn't leave a way to connect to the rebar. I don't have any metal lines coming into the building. Just some pex and pvc from the power. Thought maybe I could just come from one of the beams.
Thanks for the information.
Thanks for the information.
colomboj
Active member
Yes the building steel should be bonded. It can be bonded at the panel, and that is the most common location. The size of the wire you need to use to bond the steel is dependent on the size of your service. #6 for 100 amp or #3 thhn feeders and #4 for 200 amp 3/0 feeders (source table 250.66) After the building steel is bonded you can actually use that to connect other grounding electrodes to the panel. I.E. you can connect those two ground rods to the steel and the water pipe, ring, rebar... all that can go right to steel (source 250.68 c 2)
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wyliesdiesels
Well-known member
As said above, bond building steel to panel ground bar.
Yes you need 2 ground rods that go to ground bar as well.
Dont add 2 addl rods(4 total) for the building steel. That wont accomplish anything.
Yes you need 2 ground rods that go to ground bar as well.
Dont add 2 addl rods(4 total) for the building steel. That wont accomplish anything.
sberry
Banned
It doesn't hurt the building steel. Having a steel building well grounded is a good thing. I never have issues, mine has a loading dock footer and a rod under it pounded right in to the water table.
wcp0611
Well-known member
Good for you. Most people seem to want to cheap out on the wiring side and whine about codes, etc. They are there for a reason. You think they care if you wire it right? It isn't going to affect them if lightning hits your building. They are there to hopefully deter your life ending early.
Toomanytools?
Well-known member
Old post here, but same question.
I have a pole building with metal siding, it needs to be bonded per inspector. I have a 200 amp panel. So I understand the need to run a #4 stranded wire from panel ground to exterior metal. What do I use to attach wire to siding? Same type of lug used in panel https://www.lowes.com/pd/Blackburn-2-Count-Copper-Lugs/4580085 ?
Does it need to be in something like (Type-LB Nonmetallic Conduit Body 90 degree fitting)? Or just screwed in with a grounding screw?
jjtrou2072
Well-known member
Didn't want to start a new thread since my question is very similar to OP's.
I have a Pre-Engineered Steel Building (my current living quarters) with 200amp 4 wire feed from Power Company. This feeds goes from meter combo box on outside of building to a flush mount breaker panel installed in a 2x4 wall. I have 2 ground rods outside of building. No connection to Rebar.
QUESTIONS
1. It sounds like I need a #4 solid copper from ground bar in breaker panel to one of the Rigid Frame's of the building. If this is correct, what fitting do people use to connect #4 copper to a steel rigid frame? Do I need to sand Primer off? Not sure I've seen this at my local Home Depot.....
2. Incoming water line is PEX so I'm assuming no grounding requirement there. However I have a 1/2inch copper propane line that comes up side of building and transitions to Black Iron at the regulator/ low pressure manifold. I'm assuming I need to run a ground from the black iron assembly to the ground bus in the panel? Can someone confirm this?
Any feedback is appreciated!
I have a Pre-Engineered Steel Building (my current living quarters) with 200amp 4 wire feed from Power Company. This feeds goes from meter combo box on outside of building to a flush mount breaker panel installed in a 2x4 wall. I have 2 ground rods outside of building. No connection to Rebar.
QUESTIONS
1. It sounds like I need a #4 solid copper from ground bar in breaker panel to one of the Rigid Frame's of the building. If this is correct, what fitting do people use to connect #4 copper to a steel rigid frame? Do I need to sand Primer off? Not sure I've seen this at my local Home Depot.....
2. Incoming water line is PEX so I'm assuming no grounding requirement there. However I have a 1/2inch copper propane line that comes up side of building and transitions to Black Iron at the regulator/ low pressure manifold. I'm assuming I need to run a ground from the black iron assembly to the ground bus in the panel? Can someone confirm this?
Any feedback is appreciated!
Lonnies Performance
Well-known member
I bought a grounding lug at Lowes that bolts to the beam & has a screw terminal for the ground wire. Yes, sand the primer off.
https://www.lowes.com/pd/Blackburn-2-Count-Copper-Lugs/4580085
wyliesdiesels
Well-known member
Do you have delta or wye service?
#1 You can get a lug that attaches to the steel.
#2 Yes all metal conduit and plumbing needs to be bonded
jjtrou2072
Well-known member
Thanks Lonnie's Performance, I will check out my local Lowe's and see if I can find a copper Lug like the one you referenced.
Can someone tell me exactly which ground wire I should use for 200amp service? Solid Copper or Stranded?
Wyliesdiesels, thanks for the info. I'm not sure what type of service I have.
Can someone tell me exactly which ground wire I should use for 200amp service? Solid Copper or Stranded?
Wyliesdiesels, thanks for the info. I'm not sure what type of service I have.
alfredeneuman
Well-known member
The requirement for a grounding electrode on outbuildings is not so much for the electrical system as it is for lightning protection.
Lonnies Performance
Well-known member
I ran a solid copper 4ga un-insulated wire from the breaker box to the steel upright structure of the building.
jjtrou2072
Well-known member
To be honest since I am living in a metal building, I'm worried about lightning more than a random short circuit to the building steel. Should lightning strike the building, I would like it to have a nice clean path to ground that doesn't involve a trip through me or my family lol.
However with that said one has to wonder how lightning would travel through a 4ga copper wire. Seems illogical.
However with that said one has to wonder how lightning would travel through a 4ga copper wire. Seems illogical.
m32825
Well-known member
A lightning strike one on end of your property or a bolt close overhead can change the potential of part of your electrical layout so that current flows. Local grounding helps control induced current flow.
alfredeneuman
Well-known member
It's better to sacrifice a #4 than your whole electrical system.
ard
Well-known member
I've read the inspector is wrong on this requirement. (Unless something you have installed is "likely to energize your siding"...)
Anyone?
The requirement is for structural steel likely to be energized. "Likely" creates another gray area.
Siding is not considered structural.
I would bond/ground both anyway - cost is only pennies and it might save something important down the road.
ard
Well-known member
On a wood pole barn with metal siding, i would thing that is a bonding clamp to each and every panel... (Screws though each panel into wood are NOT 'bonded connections') Grind off paint (or whatever coating comes on the panel), then bolt on a clamp.
Id hate to run a wire or two to the siding, then have an inspector demand each piece of metal be bonded- or that all panels be 'connected' with clamps, bolts and removal of paint/coatings
sberry
Banned
They don't require each piece to be connected. Its a good idea to connect one though and may even be required. I don't believe it said any structural steel but merely steel. But,,,,, been a long time since I read every code line so that's the disclaimer.
If this is on a steel building the sheets are screwed to steel frame.
If this is on a steel building the sheets are screwed to steel frame.
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nsula_country
Well-known member
Would my building be considered "grounded" if it has 12, 5" drill stem 3' in concrete? All joints welded to each other. Curious. Had thought about adding a rod to the structure. For lightning.
CT
CT
Steel buildings easily solve the bonding of sheeting.
Code says structural metal that create a frame for the building "likely to be energized". NEC 250.104(C)
Toomanytools?
Well-known member
sberry
Banned
It doesn't follow the code definition but in reality is probably about as good as it is going to get. A little could depend on soil condition and where water table was.