Wiring pole barn for client in MI

wacnstac

Member
Hello. I'm wiring a pole barn for a client in Michigan using PVC conduit from the home to the pole barn. The way I interpret [FONT=&quot]250.122 is that the barn should not be bonded and should not have a separate ground rod but rather the ground in the barn should be run back to the home where it is bonded in the panel and there are ground rods.

Is this correct?[/FONT]
 

Little Bill

Moderator
Staff member
Hello. I'm wiring a pole barn for a client in Michigan using PVC conduit from the home to the pole barn. The way I interpret 250.122 is that the barn should not be bonded and should not have a separate ground rod but rather the ground in the barn should be run back to the home where it is bonded in the panel and there are ground rods.

Is this correct?
First of all, 250.122 is for EGC (Equipment Grounding Conductors), which you should run in the feed with the other conductors.
The panel in the barn would be a subpanel and you're correct in that it should not be bonded, meaning the neutral (grounded conductor) is not bonded to the EGC or panel cabinet.

You DO need two ground rods (if that's what you are using for a GEC [grounding electrode conductor]). You connect the GEC from the rods to the EGC bar and not the neutral bar.


Welcome to the forum!
 

wacnstac

Member
First of all, 250.122 is for EGC (Equipment Grounding Conductors), which you should run in the feed with the other conductors.
The panel in the barn would be a subpanel and you're correct in that it should not be bonded, meaning the neutral (grounded conductor) is not bonded to the EGC or panel cabinet.

You DO need two ground rods (if that's what you are using for a GEC [grounding electrode conductor]). You connect the GEC from the rods to the EGC bar and not the neutral bar.


Welcome to the forum!
Sorry, typo on the NEC section number. There are two ground rods at the house connected to the ground bar at the main panel which is bonded. Does this count as the GEC for the non-bonded ground (at pole barn) running back to the house from the pole barn (and tied into the ground bar at the house)? Or does the non-bonded ground bar at the pole barn need to be connected to two ground rods at the pole barn? This is where the confusion for me always starts when using non metalic feeder conduit to the barn.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Or does the non-bonded ground bar at the pole barn need to be connected to two ground rods at the pole barn? This is where the confusion for me always starts when using non metalic feeder conduit to the barn.
The barn requires its own GES; a metallic conduit does not change this.
 

Little Bill

Moderator
Staff member
First of all, 250.122 is for EGC (Equipment Grounding Conductors), which you should run in the feed with the other conductors.
The panel in the barn would be a subpanel and you're correct in that it should not be bonded, meaning the neutral (grounded conductor) is not bonded to the EGC or panel cabinet.

You DO need two ground rods (if that's what you are using for a GEC [grounding electrode conductor]). You connect the GEC from the rods to the EGC bar and not the neutral bar.


Welcome to the forum!
Sorry, typo on the NEC section number. There are two ground rods at the house connected to the ground bar at the main panel which is bonded. Does this count as the GEC for the non-bonded ground (at pole barn) running back to the house from the pole barn (and tied into the ground bar at the house)? Or does the non-bonded ground bar at the pole barn need to be connected to two ground rods at the pole barn? This is where the confusion for me always starts when using non metalic feeder conduit to the barn.
I said you needed the GES/ground rods (in red above). I did fail to say at the barn but that's what we were talking about and assumed you knew what I meant.
As Larry said, you need a GES at both the house and the barn and has nothing to do with whether you run a wire EGC or metal conduit.
 

kwired

Electron manager
What are you running to the "barn"? If it is a multiwire branch circuit you are not required to install a grounding electrode at the second structure. If it is feeder or service you must install a grounding electrode at the second structure. If it is service - you bond the grounded conductor like you do at any other service, since you said you are supplying it from the house it is likely either MWBC or a feeder though. If it is a feeder you still need a grounding electrode at the second structure but you tie it to the EGC instead of the grounded conductor (neutral).
 

wacnstac

Member
What are you running to the "barn"? If it is a multiwire branch circuit you are not required to install a grounding electrode at the second structure. If it is feeder or service you must install a grounding electrode at the second structure. If it is service - you bond the grounded conductor like you do at any other service, since you said you are supplying it from the house it is likely either MWBC or a feeder though. If it is a feeder you still need a grounding electrode at the second structure but you tie it to the EGC instead of the grounded conductor (neutral).
It is what I would consider a feeder (feeding a multicircuit box in the barn). 4 wires underground (hot, hot, neutral, and ground all tied into the same at the house). I have the same understanding, that the pole barn needs its own grounding electrode tied into EGC which in this case is not bonded to neutral in the barn.
 

kwired

Electron manager
It is what I would consider a feeder (feeding a multicircuit box in the barn). 4 wires underground (hot, hot, neutral, and ground all tied into the same at the house). I have the same understanding, that the pole barn needs its own grounding electrode tied into EGC which in this case is not bonded to neutral in the barn.
That is correct.
 

GeorgeB

ElectroHydraulics engineer (retired)
You DO need two ground rods (if that's what you are using for a GEC [grounding electrode conductor]).

Let's raise the ugly UFER head again ... new pole barn, maybe concrete floor on grade with steel, if so that must be the GEC connection.
 

augie47

Moderator
Staff member
Two questions:
Is the barn used for housing livestock ?
Are you actually wiring the barn in MI (Mineral-Insulated Cable) or did you mean MC ??
 

K8MHZ

Senior Member
Two questions:
Is the barn used for housing livestock ?
Are you actually wiring the barn in MI (Mineral-Insulated Cable) or did you mean MC ??
MI as in Michigan and Michigan does not enforce NEC Art. 547 at all.
 

electrofelon

Senior Member
Let's raise the ugly UFER head again ... new pole barn, maybe concrete floor on grade with steel, if so that must be the GEC connection.
Only if the slab is also the footing or structural, and there is no vapor retarder under it (which there should be).
 

Strombea

Member
250.32(A)

Exception:  A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the normally non–current-carrying metal parts of equipment.


The way I've always understood this is that it is not required if you're supplying a separate building with a multi wire branch circuit because this typically would be less than 50 A so a number 4 wire may be a little excessive and you're sending a ground from the house. I would discuss this with the AHJ. I wish the NEC would simply state if you're supplying a building or shed of less than 50 Amps no electrode is required as none of us would put any electrode in the tool shed just because it has a lightbulb.
 

roger

Moderator
Staff member
250.32(A)
Exception: A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the normally non–current-carrying metal parts of equipment.
See post #8, the OP states he it is a feeder.

Roger


 

kwired

Electron manager
250.32(A)

Exception: A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the normally non–current-carrying metal parts of equipment.


The way I've always understood this is that it is not required if you're supplying a separate building with a multi wire branch circuit because this typically would be less than 50 A so a number 4 wire may be a little excessive and you're sending a ground from the house. I would discuss this with the AHJ. I wish the NEC would simply state if you're supplying a building or shed of less than 50 Amps no electrode is required as none of us would put any electrode in the tool shed just because it has a lightbulb.
This applies to more than just a house and a shed. It applies to any stand alone structure. Some common ones where you might not add an electrode being light poles, signs, gates, fuel dispenser, the vacuum station at car wash facility, drive up kiosks, a receptacle for an RV to plug into...
 
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