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Thread: Best way to Lay/run large electric cable..

  1. #1
    830profistar
    Guest

    Best way to Lay/run large electric cable..

    So our wind turbine project has started, and one job we are tackling ourselfs is the laying of cables.

    however, to avoid digging up a lot of concrete and other obsticles, some of it will be underground, and some will have to be along the gable end of sheds.

    so whats the best way underground? (cheapest and easiest)
    Dig trench, and put in purple coils of tube and pull cables through,
    Dig trench, lay sand, then cables, then more sand, or the easiest but suspect the most expensive dig trench, lay the solid split ducting, then bury.

    Then through the sheds, the tidyest and best option we can think of it two runs of 50mm galvanised cable tray. (Probably about 80m inside to do!)

    one of the cables is 35mm2 3 core SWA power cable
    another of the cables is 25mm2 3 core SWA power cable

    (the above two must apparently be kept 18inches apart all along the route)

    and there are also two 5 core SWA signal cables to be buried along with the others.

    any thought? how would you do it?

  2. #2
    kennyo
    Guest

    Re: Best way to Lay/run large electric cable..

    we've just done ours. 18" bucket on 360. sand in with manitou cable s in. one either side of hole then sand on top.

    Its a bugger what ever you do. I would suggest making a reeler for the cable drum. We just had it held on a shaft with a forklift either side and then dragged the cable out with tractor/ by hand.

    problem we had was due to space restrictions we could dig the full track before we reeled out the cable.

    still got it to fit round shed to meter point. we had two signal cables and two 30 mm dia 3 cores aswell. two c&f 20s going up.

  3. #3
    830profistar
    Guest

    Re: Best way to Lay/run large electric cable..

    Sounds like pretty much exactly what we will do, neighbour is comming with his 360 to do the digging, got 2 c&f 15s going up, its the most we can do being split phase. nearest turbine is 250m from meters, 150m in field, 80 through sheds, then 30 through garden through 3ft stone wall (will be interesting) to meters. other one is 75 m further away.

    whatever route we took there was going to be a lot of digging and faffing!

    seeing as your in the same boat, where did you get your cable? what distance did you go?

  4. #4
    BlueWurzel
    Guest

    Re: Best way to Lay/run large electric cable..

    I think you will find 50mm tray a bit on the small side, I would go for heavy duty 75mm bolted with zebedees onto a section of unistrut.

  5. #5
    830profistar
    Guest

    Re: Best way to Lay/run large electric cable..

    Not much experience of cables, would 50mm not take 1 power cable and one comms cable? some of its steel beams, some of its timber, so 20ft bays, some 10ft.
    How big a span can that stuff go before needing support?

  6. #6
    defender
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    Not much experience of cables, would 50mm not take 1 power cable and one comms cable? some of its steel beams, some of its timber, so 20ft bays, some 10ft.
    How big a span can that stuff go before needing support?
    it should although depends on the size of the 5 core , a 35m2 cable would have an overall diameter of 30mm and anything up to a 6mm2 5 core would be less than 20 mm overall

  7. #7
    fermerboy
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    so whats the best way underground? (cheapest and easiest)
    Dig trench, and put in purple coils of tube and pull cables through,
    Dig trench, lay sand, then cables, then more sand, or the easiest but suspect the most expensive dig trench, lay the solid split ducting, then bury.

    Then through the sheds, the tidyest and best option we can think of it two runs of 50mm galvanised cable tray. (Probably about 80m inside to do!)

    one of the cables is 35mm2 3 core SWA power cable
    another of the cables is 25mm2 3 core SWA power cable

    (the above two must apparently be kept 18inches apart all along the route)

    and there are also two 5 core SWA signal cables to be buried along with the others.

    any thought? how would you do it?
    Don't for gods sake put in ducting and try to pull the cable through Its just about impossible with any major length. A few round here have come unstuck at this.
    We put ours in on sand, don't need much if its good ground, more if its stoney.

    As for inside, cable tray seems as good an idea as any.
    Never heard of this 18" apart before. Assume this is in case of heat buildup, mind you properly sized cable won't be heating up anyway.

  8. #8
    830profistar
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by fermerboy View Post
    Don't for gods sake put in ducting and try to pull the cable through Its just about impossible with any major length. A few round here have come unstuck at this.
    We put ours in on sand, don't need much if its good ground, more if its stoney.

    As for inside, cable tray seems as good an idea as any.
    Never heard of this 18" apart before. Assume this is in case of heat buildup, mind you properly sized cable won't be heating up anyway.
    A right, might give the ducting a miss then.

    its mint energy we are dealing with and thats one of their requirements, reading their T's&C's and they seem to have got themselfs covered in every possible way!
    cost of this seems to be growing every day, didnt know till yesterday that youve got to get every load of concrete tested! another 300 or so pounds a turbine! as if readymix aint expensive enough round here!

  9. #9
    fermerboy
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    A right, might give the ducting a miss then.

    its mint energy we are dealing with and thats one of their requirements, reading their T's&C's and they seem to have got themselfs covered in every possible way!
    cost of this seems to be growing every day, didnt know till yesterday that youve got to get every load of concrete tested! another 300 or so pounds a turbine! as if readymix aint expensive enough round here!
    The concrete testing is a fairly new development, c&f have had a problem or two with the hinge bolts pulling out of substandard concrete when folding up.

    Hell of a pressure at that point, the design of the base has changed a bit lately too.

    The problem with concrete testing is when it fails at 28 days old, you have a very expensive base for a ring feeder.

    There was one base that tested out at 10n/m when it was C 28/35 that was ordered.

    Think that skimping by the concrete guys plus adding a lot of water to make it easier to work is the problem. Some concrete has spoiled a bit with settling out in trailers being pulled up the side of some hill.

    Notice the spec has been upped anyway, think it is up to 37 now.

    Lot of arse covering going on!!!!

  10. #10
    defender
    Guest

    Re: Best way to Lay/run large electric cable..

    is it not the signal wire that has to be 18 inches away ?

  11. #11
    dragon farmer
    Guest

    Re: Best way to Lay/run large electric cable..

    instead of bedding on sand could you be supplied with quarry dust or similar. in my area we can get china clay grit and its half the price of sand, this is what i used!!

  12. #12
    d4c24a
    Guest

    Re: Best way to Lay/run large electric cable..

    pulling cables through ducting is not a problem as long as you lay the ducts properly ,level and straight ,and do not try and go around sharp corners
    most fail at pulling due to a draw rope not up to the job

  13. #13
    robbie c
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by d4c24a View Post
    pulling cables through ducting is not a problem as long as you lay the ducts properly ,level and straight ,and do not try and go around sharp corners
    most fail at pulling due to a draw rope not up to the job
    exactly what i was thinking, good rope and a jib of a digger etc to pull it, also never place telecom cables in the same duct as a power cable as the interference from the electric will disturt the signal, qurray dust is cheaper then sand and with a good machine driver and careful laying there is no need for sand underneath unless its very rocky, if you have a sharpish bend to go round use a long radius bend or if its going to be very sharp youl'll have to build a manhole..

  14. #14
    kennyo
    Guest

    Re: Best way to Lay/run large electric cable..

    I ordered our cable from Mercross Electrical http://www.mercross.com/page.php?dom...ewpage=contact on Quavers recommendation.

    Cable actually came direct from BATT Cables in Edinburgh don't know if they deal direct though.

    They were a pound a meter cheaper than getting MINT to supply it.

    We did the mains upgrade a few weeks before when it was dry. We just pulled the 180mm cable straight into a sanded track with no problems but it was in a better location and they had a proper thing to go on the cable to pull it and a proper cable drum reeler.

    We used approx one 1 of sand for 10 metre of track (top and bottom) for the supply cable. Used more for our turbine cables cause my men were being a bit generous. Sand is only approx 11/ t here and quarry is only 5 miles away.

    Still got our cable to route inside the shed but going to get my tatties planted first- still wiating on the dreaded half hourly metering before we can get turbine connected anyway.

  15. #15
    d4c24a
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by robbie c View Post
    exactly what i was thinking, good rope and a jib of a digger etc to pull it, also never place telecom cables in the same duct as a power cable as the interference from the electric will disturt the signal, qurray dust is cheaper then sand and with a good machine driver and careful laying there is no need for sand underneath unless its very rocky, if you have a sharpish bend to go round use a long radius bend or if its going to be very sharp youl'll have to build a manhole..
    i have used the track of a machine as a capstan winch before ,works well :lolk:

  16. #16
    SPACE COWBOY
    Guest

    Re: Best way to Lay/run large electric cable..

    We have just put 25mm overhead cable through 32mm ducting to go in the ground to supply a sheep shed 280m away. I lay the ducting down a bank first and fed 6mm rope through with a couple of long impact sockets at the end to feed it through, lifting the pipe up every so often.
    Then we attatched the rope to the cable and fed through while pushing and pulling worked ok. Even tho my arms are like a gorilla now

  17. #17
    lamplighter2
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    A right, might give the ducting a miss then.

    its mint energy we are dealing with and thats one of their requirements, reading their T's&C's and they seem to have got themselfs covered in every possible way!
    cost of this seems to be growing every day, didnt know till yesterday that youve got to get every load of concrete tested! another 300 or so pounds a turbine! as if readymix aint expensive enough round here!
    re redimix what are they asking for give this to the mixing yard and will mix it to the spec. but i bet its just normal mix. re redimix have you tried hansons plenty of firms doing redimix other than the normal one,s re cable what about putting a mole through do not know costs save digging

  18. #18
    830profistar
    Guest

    Re: Best way to Lay/run large electric cable..

    Readymix here is a bit limited in choice, last time i checked it was i think 110 a cube, and the competition was about 97. might be wrong but its c30 grade they want i think? (might be wrong)

    sand quarry is really just over the fence from us, think its 9 something a ton, could probably get it off our own land and just sort out any large stones, or if no one was looking, open the gate to the beach and get a load or two.

  19. #19
    jumbojimbo
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    So our wind turbine project has started, and one job we are tackling ourselfs is the laying of cables.

    however, to avoid digging up a lot of concrete and other obsticles, some of it will be underground, and some will have to be along the gable end of sheds.

    so whats the best way underground? (cheapest and easiest)
    Dig trench, and put in purple coils of tube and pull cables through,
    Dig trench, lay sand, then cables, then more sand, or the easiest but suspect the most expensive dig trench, lay the solid split ducting, then bury.

    Then through the sheds, the tidyest and best option we can think of it two runs of 50mm galvanised cable tray. (Probably about 80m inside to do!)

    one of the cables is 35mm2 3 core SWA power cable
    another of the cables is 25mm2 3 core SWA power cable

    (the above two must apparently be kept 18inches apart all along the route)

    and there are also two 5 core SWA signal cables to be buried along with the others.

    any thought? how would you do it?
    We did similar with a large 3 phase internal supply we had to get from one end of the farm to the other. Turned out to be a costly mistake when 18 months later we had a fire in one of the sheds we put the supply line through and spent the next few weeks on a generator. Now all the cables areburried where nothing can damage them, better to do the job properly first time

  20. #20
    Rossco
    Guest

    Re: Best way to Lay/run large electric cable..

    We bought our cable direct from Batt Cables Aberdeen, quite happy to deal direct.

  21. #21
    sawdust
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by SPACE COWBOY View Post
    We have just put 25mm overhead cable through 32mm ducting to go in the ground to supply a sheep shed 280m away. I lay the ducting down a bank first and fed 6mm rope through with a couple of long impact sockets at the end to feed it through, lifting the pipe up every so often.
    Then we attatched the rope to the cable and fed through while pushing and pulling worked ok. Even tho my arms are like a gorilla now
    Easiest way to put drawcord through ducting is to tie a tesco bag to the drawcord and blow it through with an industrial compressor, you can blow it hundreds of meters no probs

  22. #22
    fermerboy
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by Rossco View Post
    We bought our cable direct from Batt Cables Aberdeen, quite happy to deal direct.
    +1

    Cheapest quote I could get at the time too.

  23. #23
    830profistar
    Guest

    Re: Best way to Lay/run large electric cable..

    While i am waiting on people phoning back with cable quotes, been looking at cable tray. looking at the Heavy Duty 225mm stuff, seems hellishly expensive, looking at near 750! needing 82m, anyone any ideas?

  24. #24
    830profistar
    Guest

    Re: Best way to Lay/run large electric cable..

    Jeezo, Batt are 1.55, 99p, and 46p a meter cheaper than mint for the cables, thats 35mm, 25mm, and 2.5mm 5 core!!!!

  25. #25
    fermerboy
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    Jeezo, Batt are 1.55, 99p, and 46p a meter cheaper than mint for the cables, thats 35mm, 25mm, and 2.5mm 5 core!!!!
    Only that small a difference!!!!!

    They have surely sharpened their pencils a bit.
    The gap was a lot more than that when I did mine.

  26. #26
    fermerboy
    Guest

    Re: Best way to Lay/run large electric cable..

    Quote Originally Posted by 830profistar View Post
    While i am waiting on people phoning back with cable quotes, been looking at cable tray. looking at the Heavy Duty 225mm stuff, seems hellishly expensive, looking at near 750! needing 82m, anyone any ideas?
    Do you need tray that big?

    I would have thought that two runs of 50mm would have done it, the 35mm/2 is only 30mm, and the 2.5mm/2 is 17mm. Both would fit on a 50mm no problem. Even a 75mm to give it more strength.

    Alternatively could you not fix 4" x 2"(bigger if a big span) wooden rails to the sheds and cable clip/cable tie them to that?

    Hell even a length of angle iron fixed to the shed and the cables clipped/tied to that, would be cheaper. 750 would buy a lot of wood or steel
    Any old zed purlins? Even a new zed purlin might be less than that.

    Just throwing in a few ideas!!!

  27. #27
    eire22
    Guest

    Re: Best way to Lay/run large electric cable..

    Your not using the ducting but if you are than handiest way is lay it and get a vacuum cleaner on one end and a roll of baler twine at the other and tie a bit of insulation to the twine and you will pull in a fish cable of any length.
    Then pull your pull in a heavier rope with it.

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