Installing overhead cable

[TheTallGuy]

For an overhead supply of that size it needs to be SWA for mechanical protection. Stainless Steel cable ties or the steel bands are the job for securing to the catenary, or you can do it with the standard SWA cable cleats trapping the catenary between the cable & the pinch bolt; leaving it loose will result in the cable sheath abrading.

Your big issue will be sag as the tension required on the catenary for a low sag level is going to require some strong fixings! If using 4 core it's around 1kg/m, 5 core is 1.3kg/m.

 

[biggles]

Ok, thanks for all the ideas and info the cable will be between two gable ends on brick built 2 story buildings. The cable will be going 90 degrees from one gable and joining the other at about 30 degrees. Was going to make a hook up on a plate and put threaded rod straight through the brickwork? Does this sound ok? Also does the wire rope I have sound adequate? Cheers

 

[biggles]

Also what level of sag on that length of run should I expect/ be aiming for? Cheers

 

[Lincs Lass]

Isn't there any way of going under ground with it ,,the pull on each end will be massive,,take notice of power poles where cables end , they have a big strainer wire into the ground to compensate for the pull ,,three point triangle ,,if you are relying solely on steel plate bolted through a brick wall then I think you heading for trouble

 

[Lincs Lass]

Theres a true saying , failure to prepare ,then prepare to fail ,, do it right, do it once even it it means getting advice from a utilities company of how they would go about it

 

[br jones]

Ok, thanks for all the ideas and info the cable will be between two gable ends on brick built 2 story buildings. The cable will be going 90 degrees from one gable and joining the other at about 30 degrees. Was going to make a hook up on a plate and put threaded rod straight through the brickwork? Does this sound ok? Also does the wire rope I have sound adequate? Cheers

A plate on the back to spread the load

 

[Exfarmer]

What about the metal potato bag ties, as long as you don’t cut through the cables.

Would rust out in a few years. Personally would snake the. Cables round each other.
years ago we installed a 3 phase supply at least that length with no support using unarmoured individual cables ( insulated of course.
do not remember having any great problems tensioning. only passed over buildings so hieght was no great issue.
i am certain you can get special cable grips to to pull the tension.
i am not aware of current regulations though

 

[tomlad]

Spud bag ties ive used are bare steel, lot thru in a month.
Presumably there must be better ones, but its a thin wire pulling, gonna cut ??

 

[gmgmgm]

Have a look at a Hammock Hang calculator to see the forces on the building: e.g. this one: http://theultimatehang.com/hammock-hang-calculator/ It's sometimes rather surprising just how much force is exerted by a hammock (or an overhead cable).

e.g. with a 15 degree slant and 50kg of cable, you'll have 100kg of "force" pulling outwards on the brickwork.
With a flatter 5 degree slant at the end, you'll have near 400kg of "force" pulling out of the brickwork.

 

[rick_vandal]

Ok then so should I cable tie the cable tight, or leave loose for expansion/contraction? Worried about chafing if left loose? Would armoured cable be the best to use or is there a better preference for overhead? Cheers

SWA is very heavy so consider Hituff. Is 10mm a calculated geusstimate and do you need to get the installation signed off? Electricians love spending our money on copper!

 

[FIL46]

This sounds a fair project, I would be carefull attaching it direct to a building you are going to have some tension pulling on that walls, is it possible to install proper wood poles next to the corner of the building and put stays 90deg along building side to hold them back, 6mm may be a bit light for the tension on that span holding 50 or 60 kg of cable and factor in some storm whatever name we are on and it may snap, I would ask expert advice on this one we farmer's are knowledgeable people but sometime knowing when to ask the expert is the best knowledge you can have

 

[defender]

If it were mine I would put ties from the bolt through the wall back to the top of the wall along inside the shed a bit to take the strain away from the gable top. Wouldn't need to be anything fancy , High tensile fence wire would be enough
A turnbuckle in the catenary wire will allow retensioning after the wire stretches , you could also use a high tensile wire rope as an alternative to lessen stretch and sag

 

[renewablejohn]

I would do the wire like the rail overhead cables using a pulley at one end and a number of weights to keep the tension at low level. Turnbuckles are just bad news.