MV on poles

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electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Occupation
Electrician
Ive got a 4000' step up step down gig for a customer who got an absurd quote from the POCO. It is actually two residences, so there needs to be two circuits. Originally it was going to be all underground, and because your typical 15KV concentric neutral able is way overkill for a single house, I looked into other cheaper options. That stuff isnt that expensive, about 2.15 per foot, but that adds up when you have two at 4000 feet each, and dont forget conduit..... I considered using #8 2KV PV wire, but that would take custom transformers. I used the 2KV PV wire for the step up step down I ran at my house and I just ran it with 2400 transformers tapped down all the way (-5%, doesn't get you all the way there), and although the wire has plenty of dielectric strength, I dont really want to do that in a professional capacity.

So I found this L-824 5KV airport lighting cable which goes down to #8, which I can run with "commodity" 4160gy/2400 padmounts. I got a cable in conduit quote for 2 of those, with a common #8 600v neutral, for $1.83 per foot. I would be set up as a MGN. So that is just some background, now for the question. Looks like the customer will have to go above ground for part of the run, maybe 1000 feet, so that means poles. What wiring method should I use on the poles? Im not sure whether to go full "utility style" and use open AAC or ASCR on insulators? Ive never done that before, but I am sure its not rocket science. Might need cross arms, the two hots on the arms and the MGN down a bit on the side of the pole. What about hendrix? I thought also about avoiding another wiring method and splices and just using the CIC and lashing it to a messenger. Not sure if the CIC is UV resistant. Would need a spiral lasher. BTW This does NOT need to be NEC compliant, but of course I dont want it to be unsafe or a hackjob. Just looking for some with experience on the pole wiring method as I have no experience with it. Thanks.
 
Why two circuits? Have the URD hit one pad then feed through to the other pad. URD is not over kill for a single home because I know of tons of installations where the POCO will set a pad next to the home or property then run it all the way back to the pole.
 
ActionDave said:
You are not exactly walking on the moon, but you sure are walking in places that few of us have traveled.
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Yeah. The issue for me is not the skills, its just not knowing parts and methods. Just looking for insulators, what are they called exactly? How does the conductor attach to the insulator? I found tie top insulators, but what do you do for turns? Just little stuff like that. At 2.4KV nothing would be that critical. That kinda why I was leaning toward something like hendrix - wouldnt be much to figure out with that.

mbrooke said:
Why two circuits? Have the URD hit one pad then feed through to the other pad. URD is not over kill for a single home because I know of tons of installations where the POCO will set a pad next to the home or property then run it all the way back to the pole.
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Two circuits are needed because they need two meters. There are two houses next to each other. They are family members so could sub meter a single feed for now, but they want to be independent in case something changes in the future

The reason I say MV URD is overkill is because it does not appear to made in sizes smaller than #2 which could serve a house with a 60 amp load at a length of about 24 miles! Most of these situations are a mile or less. I have #12 CU (2KV PV wire) serving my house at 2.4 KV, 2000 feet. IF you are following NEC, there is a minimum size of #8, so that airport lighting cable is affordable (much cheaper than MV90) and meets the minimum size. Probably the cheapest option would be #8 AL PV wire, but again you are stuck at 2 KV max if you doint want to exceed the marked cable rating. For overhead, im not sure what the minimum size would be. I think they make #6 ASCR, but would have to look at strength and distance between poles.
 
electrofelon said:
Yeah. The issue for me is not the skills, its just not knowing parts and methods. Just looking for insulators, what are they called exactly? How does the conductor attach to the insulator? I found tie top insulators, but what do you do for turns? Just little stuff like that. At 2.4KV nothing would be that critical. That kinda why I was leaning toward something like hendrix - wouldnt be much to figure out with that.



Two circuits are needed because they need two meters. There are two houses next to each other. They are family members so could sub meter a single feed for now, but they want to be independent in case something changes in the future

The reason I say MV URD is overkill is because it does not appear to made in sizes smaller than #2 which could serve a house with a 60 amp load at a length of about 24 miles! Most of these situations are a mile or less. I have #12 CU (2KV PV wire) serving my house at 2.4 KV, 2000 feet. IF you are following NEC, there is a minimum size of #8, so that airport lighting cable is affordable (much cheaper than MV90) and meets the minimum size. Probably the cheapest option would be #8 AL PV wire, but again you are stuck at 2 KV max if you doint want to exceed the marked cable rating. For overhead, im not sure what the minimum size would be. I think they make #6 ASCR, but would have to look at strength and distance between poles.
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Not over kill when POCOs use those sizes to serve little cell towers. 15K fuse (15 amp, K= fast blow) at the pole and a 10kva pad mount.

Don't exceed the cable markings- as you go up in voltage you get corona and tracking which will eat away at the cable insulation.

If overhead the wire size would be #6 minimum, but you must factor in spacing, ice loading ect. NESC is the best guide. And honestly, I'd avoid #6 seeing just by how many times it breaks in the real world. Something like 1/0 ACSR is overkill, but larger sizes basically do not break when a tree branch comes down. 556 takes down the cross arms if not the poles, but it never breaks lol.
 
https://www.macleanpower.com/assets/resource_library/5A4E35026F1741D28920EE485ED22D8B.pdf

this might get you pretty far


you use dead end clamps for the wires at the end poles or turns in the run, you use pin insulators for the field of the run, you can buy some preformed ties, we just use solid wire, there are a few decent videos on youtube on methods of lashing. we use pole sheaves, come-a-longs and cable grips to get the wire in place. probably a good idea for cutouts at the end poles, you will also want guy wires there going down to the ground with a ground anchor we use preform wire ties for guy wires, get the yellow sleeves for lawnmowers. double nut hardware that goes through wood, the wood shrinks and the hardware will be loose in 3 years. the epoxy insulators i have seen used show signs of tracking in less than 5 years, haven't seen them fail, but i see electrical trees in them, that makes me like porcelain, we use LAPP brand, don't use one with a chip in it. 1/2" impact for drilling holes works great. we use https://www.hubbell.com/hubbellpowe...rdware/Brackets/For-Conduit/Standoff/c/561365
these for conduit up the pole. we use something like these for the vertical insulated cable support https://www.hubbell.com/hubbellpowe...ITIONER-CABLE-WITH-MOUNTING-BRACKET/p/1646259 , although i have seen utilities that use nothing in place of it but i recommend them. we have a local utility material supplier that we get everything from, i wouldn't be surprised if you have one near you, i'm not a lineman i've just been on a few inside the fence(non-utility) overhead projects. use surge arresters at least on one end of that length. we ran butt grounds on every pole, staple the ground wire to the top of the pole, use an axle and run the spool down to the bottom, use your peavey and wire grip to pull the ground taught and straight and then have your helper staple it at bottom of pole and then staple the field of the wire up the pole, coil up some and staple it to the bottom of the pole. this is just a brief overview. we used 10% + 2 for burial depth, so if you have 60' poles they go in the gorund 10%(6') + 2'=8" in undisturbed soil, we have clay soil around here below about 1-2'topsoil

https://www.youtube.com/watch?v=8AeMMdgYR4M


Try ElectricianTalk there are linemen on there.
 
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thought of some more.

compact the fill whether dirt or stone, if you are renting a derricks you can try to get one with hydraulic accessory connections and a hydraulic tamper.
you use the derricks to run the guy anchors in the ground, buy a couple extra because you will probably bend a few getting the hang of it.

it'll probably be fun and a change of pace if you have plenty of time to prepare and study and plan. i really enjoy doing it every once in a while
 
Wire-Smith said:
thought of some more.

compact the fill whether dirt or stone, if you are renting a derricks you can try to get one with hydraulic accessory connections and a hydraulic tamper.
you use the derricks to run the guy anchors in the ground, buy a couple extra because you will probably bend a few getting the hang of it.

it'll probably be fun and a change of pace if you have plenty of time to prepare and study and plan. i really enjoy doing it every once in a while
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Great info and crash course, thanks, that really helps.

Still in a holding pattern with the job. The client is still trying to get service from the POCO and seems to be having a real hard time. They have a formal easement from the adjacent property owner, but POCO says they cant put a meter on someone elses property even with an easement per their NYS tariff. Hopefully they will get some resolution before too long.
 
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