Running 35mm armoured overhead

[Robertbaker63]

A farmer wants me to run a new supply to a building, it's to be run in 35mm armoured, part of the route is a 25m overhead span between buildings, is this okay for the cable or should I be getting an extra pole in the middle put in to take the weight

 

[Brightspark2]

unsupported over 25m?

Oops missed that bit!!...ha ha

 

[shanky887614]

Oops missed that bit!!...ha ha

if there are no supports over the 25m i recon it might dislodge a brick before landing on the ground

thats only my opinion i have never used catinery wire so i honestly don't know but i recon the manufacturer's will have the recommended support distances with loadings in there paperwork

 

[nickblake]

used cateenary wire loads of times normally over short distances but not over that distance and with that size cable

 

[Guest77]

Yes it's 3 core armoured, the overhead part is not in a.through vehicle route and not possible to go underground as it's over a few smaller sheds

You need to completely redesign the whole job, it is not possible to support a cable that size on cateenery wire over that distance, a rethink, no point trying to continue down the cateenery route, just pointless.

 

[Guest77]

A cable of that size run overhead should be fully supported and usually with heavy duty cable ladder, this would also require frequent support poles as you have to account for the weight of the ladder too and its max unsupported recommendations (at a guess every 5m) and been a farm then at a suitable height for farm plant to cross under even with any folks etc raised.

I would be seriously looking into burying this given the cost and obvious hazards having a overhead system with multiple supports would present on a farm.

Good advice, I agree a ladder with supports or get it in the ground.

 

[Dcf]

What about abc type cable or the old fashioned method of type 8 overhead channel iron and insulators at each end?
whatever method you decide the fixings will need to be rock solid at each end

 

[Darkwood]

I think the sheer cost of Ladder, post digging, bare or insulated singles wires overhead method all come with large costs, although burying it would in no doubt increase the CSA requirement you should still cost it up and ask the farmer to do the digging work if he can to keep costs low.

All methods are going to be a pain and a knock in his pocket but if that's the power he needs then he has to accept its going to be expensive.

 

[benji]

RS do a 30mtr catenary kit that seems to carry 130kg ? and the dia. is only 3.0mm ??.Today i was looking at a catenary suspended between poles for street lighting approx 25mtr apart total run about 200mtr cable looked about a 25mm swa ? (i was driving at the time ) very little sag between poles and its been there for years.

 

[shanky887614]

RS do a 30mtr catenary kit that seems to carry 130kg ? and the dia. is only 3.0mm ??.Today i was looking at a catenary suspended between poles for street lighting approx 25mtr apart total run about 200mtr cable looked about a 25mm swa ? (i was driving at the time ) very little sag between poles and its been there for years.

might do it. 100m of 35mm 4c is 240kg so should work.


the problem isnt the cable but the fixings either end.

those supports have cable supports as well to keep them up usually and you will need a concrete base etc for them.

it might be cheaper to find a longer route and use a bigger cable, quick search online and 35mm 4c is £9ish a M

so thats £280 just on cable (30m)

70mm is £13pm = £390 (30m)

i bet the cost of poles and everything else will add upto a lot more than installing a bigger cable and going underground or a longer distance

 

[benji]

Correct but if distance is only 25mtr pole might not be required but the fixing of the catenary at each end needs to be paramount

 

[shanky887614]

Correct but if distance is only 25mtr pole might not be required but the fixing of the catenary at each end needs to be paramount

thats the problem.

how many farmers look after there buildings etc? there among the worst for bodges

 

[Guest77]

RS do a 30mtr catenary kit that seems to carry 130kg ? and the dia. is only 3.0mm ??.Today i was looking at a catenary suspended between poles for street lighting approx 25mtr apart total run about 200mtr cable looked about a 25mm swa ? (i was driving at the time ) very little sag between poles and its been there for years.

An experienced Time served Electrician wouldn't consider it :icon12:

 

[D Skelton]

Catenary is possible, but you'd need to sink two proper telegraph poles, plus counter anchoring. He's gonna need deep pockets!

If you're going overhead, I'd also ditch the SWA and go for HO7RNF.

 

[shanky887614]

An experienced Time served Electrician wouldn't consider it :icon12:

Catenary is possible, but you'd need to sink two proper telegraph poles, plus counter anchoring. He's gonna need deep pockets!

If you're going overhead, I'd also ditch the SWA and go for HO7RNF.

thats the thing it soon gets expensive, one of the biggest reasons the dno goes above surface is its cheaper than burying and making good in certain cases.

if you think about the logistics of it, it makes sence.

 

[D Skelton]

I've suspended 5 core 70mm HO7 over a gap of 20m before, but I was securing the catenery to solid concrete on one side, and a metallic ship hull on the other. It is easily doable, but if you're doing it at height, which I wasn't, it needs to be done properly!