cable length

[neil_ev]

Hi there,

I've been asked by a farmer to replace the overhead cable going from the house to some of the sheds. The cable goes from the house to Shed A where it splits in a consumer unit and onto Sheds B and C. When calculating voltage drop to I enter the entire length (i.e. from house to Shed B/C) or do I calculate each section individually?

thanks

 

[Rockingit]

Think about it. The load at A = (A)BC, the load at B = (BC).

 

[neil_ev]

Think about it. The load at A = (A)BC, the load at B = (BC).

my brain doesn't cope too well with cryptic equations on the weekend.......

 

[Rockingit]

OK, well if A feeds B, and B has a load of 10A, what is the load at A?

 

[Silly Sausage]

do I calculate each section individually?

Yes.
Also, depending on the loads at the sheds, you could possibly use a cable with a smaller csa for the second section.

 

[Knobhead]

Out of interest what kind of cable are you planning on using?

 

[telectrix]

round, i think......

 

[snowhead]

Out of interest what kind of cable are you planning on using?

Wireless??

 

[JD6400]

This one has got me thinking ( Not quite enough to reach for the regs mind , as the fire is roaring ,I've got a full belly and this recliner is working it's magic!:snore
But I regularly come across over head farm supply's , in fact we have a whole farm rewire to start within a few weeks for one of the local estates that we look after because of a ( originally ) damaged over head cable .
Near on every one I come across that is feeding more than one building , is of a main unbroken cable ( singles ) that has a taping at each take of point .
I always prefer to take individual buried sub mains to each building when we do a farm rewire , but I can not for the moment think of a reg that would prohibit the original method , apart from maybe issue's with segregation of circuits ?

What do others think !?

 

[Rockingit]

Ooh...here's a contentious one: Armour as catenary. [lights touch paper and stands well back.....]

 

[JD6400]

Ooh...here's a contentious one: Armour as catenary. [lights touch paper and stands well back.....]

That's a good one !
Not that we have run an overhead for a long time now ( main reason for going into trenchless technologies in the first place !), but if it were to be run in swa , a separate catenary is a must .

 

[Guest55]

This one has got me thinking ( Not quite enough to reach for the regs mind , as the fire is roaring ,I've got a full belly and this recliner is working it's magic!:snore
But I regularly come across over head farm supply's , in fact we have a whole farm rewire to start within a few weeks for one of the local estates that we look after because of a ( originally ) damaged over head cable .
Near on every one I come across that is feeding more than one building , is of a main unbroken cable ( singles ) that has a taping at each take of point .
I always prefer to take individual buried sub mains to each building when we do a farm rewire , but I can not for the moment think of a reg that would prohibit the original method , apart from maybe issue's with segregation of circuits ?

What do others think !?

well if the main cable is adequately sized to carry the total load then youre good to go.
no different to T-joints for each connection point on a highways supply, no different to bus bar line taps for each piece of factory equipment , etc etc.

 

[Knobhead]

If you’re planning on using OH singles look for type 16 660V insulated hard drawn copper. It’s available from 14mm to 100mm.

You will need a staining clamp and pull lifts to tension it. God help you with the larger sizes. The regulations cover minimum clearance. For tying to the insulators there are preformed hard wire insulated binders (can’t remember what they are called.)



The first one I got lumbered with was on our private network 3Ph+N. I used line taps and shrouds to drop down in sheathed singles (CU tails) at each tap off point. A bare earth conductor was run to extend the overall earth nest via rods at each drop.

It was a weird system as it was fed off our 2.5KV system which was stepped down to 550V for use on the plants. It then stepped down again from 550 3Ph to 433V 3Ph+N to feed the village.

It was quite a fun job once we got stuck in. It was the middle of summer though, wouldn’t fancy it at this time of year. A couple of the drops were to local pubs, things went a bit haywire then. Mrs, Storrer at the Railway Inn got our mark, “no beer until the powers back on!” Not much got done afterwards.

It was brilliant, we had an entire village to do. Each house had to have a RCD fitted and new supply. Go to house 1, “sit the’ sen down lad, here’s breakfast.” On to house 2, “I’ve just done dinner, sit down.” House 3, , , ,

We were all 3[SUP]rd[/SUP] and 4[SUP]th[/SUP] year apprentices on overtime at the weekend, the job took a lot longer than it should. we put a lot of weight on.

 

[Guest55]

man , that hard drawn stuff is a bitch to work with lol.