Equipotential Bonding/Farm Buildings

[jmellc]

Still haven't done any of this myself. I am talking with my father in law about a new service for his farm buildings. He has an OLD main disconnect at service pole, fusible, with multiple taps off to a barn, several sheds & the house. Main is mounted on boards long decayed, hanging by a thread. Cables go through drilled or punched holes in sheet metal walls of buildings. Most cable has long been showing outer cu or al neutral.

He wants to tear down 1 shed, no problem there. Barn & other shed or 2 have concrete floors. For EB, I am thinking chipping off outer corners to find any rebar or screen wire and bonding to it, run a grnd wire all around, bonding to siding with open ground clamps & rebar/wire at each corner. Would this be effective in an existing building? Have any of you had a similar situation?

 

[hurk27]

Still haven't done any of this myself. I am talking with my father in law about a new service for his farm buildings. He has an OLD main disconnect at service pole, fusible, with multiple taps off to a barn, several sheds & the house. Main is mounted on boards long decayed, hanging by a thread. Cables go through drilled or punched holes in sheet metal walls of buildings. Most cable has long been showing outer cu or al neutral.

He wants to tear down 1 shed, no problem there. Barn & other shed or 2 have concrete floors. For EB, I am thinking chipping off outer corners to find any rebar or screen wire and bonding to it, run a grnd wire all around, bonding to siding with open ground clamps & rebar/wire at each corner. Would this be effective in an existing building? Have any of you had a similar situation?

I would doubt very much your going to find any metal screen or rebar in older type structures like this, even today here it is rare anyone puts rebar in flat work unless required.

Never done many barns and the ones I did were granfathered in, but I have had to cut lines into pool decks and cement copper wire into them before to create an EPG luckly it was having tile over it so you didn't see the cuts, does he have live stock that might be effected?

I would say one thing to make sure is that all service neutrals are not under sized and the connections are the best you have ever done, as voltage drop on the service/feeder neutrals are the main source for stray voltage, the MGN from the primary can also be a problem but in many cases its hard to get any thing done about it.

 

[Fulthrotl]

Still haven't done any of this myself. I am talking with my father in law about a new service for his farm buildings. He has an OLD main disconnect at service pole, fusible, with multiple taps off to a barn, several sheds & the house. Main is mounted on boards long decayed, hanging by a thread. Cables go through drilled or punched holes in sheet metal walls of buildings. Most cable has long been showing outer cu or al neutral.

He wants to tear down 1 shed, no problem there. Barn & other shed or 2 have concrete floors. For EB, I am thinking chipping off outer corners to find any rebar or screen wire and bonding to it, run a grnd wire all around, bonding to siding with open ground clamps & rebar/wire at each corner. Would this be effective in an existing building? Have any of you had a similar situation?

this is just utility buildings, not dairy production, right?

grounding and bonding milking sheds is a big deal.....
if not done correctly, critters won't give milk.

 

[jmellc]

this is just utility buildings, not dairy production, right?

grounding and bonding milking sheds is a big deal.....
if not done correctly, critters won't give milk.

One shed used to be a dairy building but he quit doing dairy in the 1970's. He still had some cows until a few years ago. He sold them all & no longer has any. To see the service in it, I am amazed any milk ever got produced. I don't think it even has a ground wire to a ground rod. Near as I recall, only ground rod is at main pole. OLD is the operative word here.

 

[jmellc]

I would doubt very much your going to find any metal screen or rebar in older type structures like this, even today here it is rare anyone puts rebar in flat work unless required.

Never done many barns and the ones I did were granfathered in, but I have had to cut lines into pool decks and cement copper wire into them before to create an EPG luckly it was having tile over it so you didn't see the cuts, does he have live stock that might be effected?

I would say one thing to make sure is that all service neutrals are not under sized and the connections are the best you have ever done, as voltage drop on the service/feeder neutrals are the main source for stray voltage, the MGN from the primary can also be a problem but in many cases its hard to get any thing done about it.

No livestock any more. How deep did you have to score & bury your copper wire? Did you go around outer perimeter or crisscross the whole pad? I discussed something like that with an inspector about a hot tub but didn't get the job, so never had to work out the details.

 

[suemarkp]

What is the goal of this update to the buildings? If the buildings don't hold livestock, and especially if they don't look like livestock buildings (e.g. a storage shed), I don't believe an equipotential system is required. If you want to make it so some future person could use it that way, then you have some retrofitting to do.

Are you going to refeed these buildings with 4 wire feeders (with insulated nuetral), or leave them as grand fathered 3 wire feeders? Just updating to 4 wire feeders helps a lot (then voltage drop in the feeder neutral doesn't matter). Not sure you need to go to the next step of having the grid or not, especially if implementation is going to be expensive.

 

[ptonsparky]

What is the goal of this update to the buildings? If the buildings don't hold livestock, and especially if they don't look like livestock buildings (e.g. a storage shed), I don't believe an equipotential system is required. If you want to make it so some future person could use it that way, then you have some retrofitting to do.

Are you going to refeed these buildings with 4 wire feeders (with insulated nuetral), or leave them as grand fathered 3 wire feeders? Just updating to 4 wire feeders helps a lot (then voltage drop in the feeder neutral doesn't matter). Not sure you need to go to the next step of having the grid or not, especially if implementation is going to be expensive.

I agree. No reason to put in an grid if it is being used for storage now.

 

[jmellc]

I'll have to discuss future uses with him. They are in their 80's, so I'm sure they will not keep animals again, not to any large scale anyway.

The main barn is storage for a tractor & other equipment, storage for various materials, etc. Has a workbench. About a 30-40 foot square building. Other buildings have mostly been used to store seed & fertilizer, etc.

My plan is to build a new rack at the pole. Build with treated lumber and mount an MDP. Put the main barn on a 100A breaker & go UG to it; short distance, easy soil to dig. Come up with PVC & LB into bldg & panel. May put new panel, haven't really checked old one out yet. 4 wire for sure.

Other buildings, I'd put on 60A breakers with small 4 or 8 ckt 60A panels. Maybe 70A if that is easier to get. They mainly need lights & receptacles, maybe small heaters of some sort. I know the old dairy building has a corroded panel with no cover, nice rat's nest kind of look. Again, 4 wire. I would run overhead triplex to them, as they are further & have dirt road in between.

House is fed from same place, UG about 150 feet to house. Rigid steel down from switch & up at house. Probably bare cable between. 3 wire. I'm sure the inspector there would want me to upgrade to 4 wire. I will ask if he would grandfather a 3 wire, due to distance & cost. But I will do as inspector wants. May even be able to reuse old wire, it is 4/0 cu, probably RHW. May be able to add a 4th wire if direct buried. Can check depth at pole end & dig carefully to find cable, lay new wire alongside. At house, it comes up through interior wall from crawl space. Haven't figured that part out yet. Wire looks good at both ends, in spite of age. I think it was installed late 50's or early 60's.

He talked to POCO about separating house from others. They told him about $5,000 to run new service to house. I think we could do the other way cheaper. I will do it for him at cost. I need to start pricing outdoor MDP's. I think a 400A would be about right; haven't priced anything like that in a long time. I think I saw a Siemens unit that was a meter/panel combo. That would be perfect.

This has been kicked around a long time. FIL wants to do it but when I tell the work involved, he loses steam & puts it off. I keep telling him the outdoor main is on borrowed time & may not survive the next storm.

 

[jmellc]

BTW, I assume I can get 4 wire triplex, or rather quadplex or 4plex? Something else I haven't used in a long time.

I just thought too, that with the siding on the barn, if I ran bare cu around the slab outside, I could mount a ground lug at every stud, use 2 inch #12 screws, through sheet metal into stud. Then run jumpers to main grnd & split bolt them. Every section of siding would have its own sure grnd & be bonded as a whole too, in case any part corroded & lost contact in its overlapping.

 

[augie47]

You might talk with your POCO.
It's not uncommon here for POCO to install a CT meter at a "maypole" and the customer has service drops to the various farm buildings form that pole. Keeps you from having to size a main at the pole for the total load and, since the drops are still 'services', you can use 3 wire triplex to the buildings.