Overhead supply cable.

[happyhacker]

What are my options if I want to suspend from the house to garage about 20m.

1. Type of cable?
2. Strain wire needed?
3. What type of cable run on walls either end?
4. Ordinary 2.5mm if in plastic conduit?
5. Need for armoured cable anywhere?

Thanks.

 

[EngStudent]

What are my options if I want to suspend from the house to garage about 20m.

1. Type of cable?
2. Strain wire needed?
3. What type of cable run on walls either end?
4. Ordinary 2.5mm if in plastic conduit?
5. Need for armoured cable anywhere?

Thanks.

1. SWA.
2. Yes, catenary required.
3. SWA.
4. No, you can't use conduit.
5. See 1 & 3.

As you're in England, it's notifiable.

 

[Stoday]

SWA with a catenary? Have you any experience with this, EngStudent? I would have thought it unsuitable for overhead.

I've installed overhead on farms some 45 years ago. The cables/wires were hard drawn copper. A cheap way then was some "HSOS" cable — House Service Overhead System, which had an integral catenary. I don't think this is available any more.

I wouldn't use SWA overhead unless someone here can recommend it based on his experience.

 

[EngStudent]

SWA with a catenary? Have you any experience with this, EngStudent? I would have thought it unsuitable for overhead.

Only way I've been taught to be honest. Though if that's wrong I'm happy to learn!

 

[Lectrician]

Split concentric used to be used for OH spans using proprietry dead-ends/pre-formed stays, however, they now no longer give maximum unsupported lengths in their technical data and refer you to BS7671 instead.

You therefor now need to install split concentric with a catenary.

If the outside portion of the cable run on the walls is not prone to damage (up out the way), then split con would be fine. Protection with conduit or capping in areas suseptable to damage would be fine.

Split concentric is available 4/6/10/16/25/35mm. It is UV stable, and FAR lighter than SWA, a real consideration when going OH.

 

[jeepmadmike]

No issue at all using swa on a catenary

I know of a big ish bit which has spanned a river on a wire rope for approaching 30years

 

[Lectrician]

Obviously size the catenary appropriately - don't just go directly to the wholesaler and get whats on the shelf - they will only have the tiddly stuff.

 

[westie101]

Split concentric used to be used for OH spans using proprietry dead-ends/pre-formed stays, however, they now no longer give maximum unsupported lengths in their technical data and refer you to BS7671 instead.

You therefor now need to install split concentric with a catenary.

If the outside portion of the cable run on the walls is not prone to damage (up out the way), then split con would be fine. Protection with conduit or capping in areas suseptable to damage would be fine.

Split concentric is available 4/6/10/16/25/35mm. It is UV stable, and FAR lighter than SWA, a real consideration when going OH.

23m for sizes over 16mm (we use it all the time with preforms) I've seen 4mm span about the same but it is not recommended and preforms for it are not part of our standard stock!

 

[Steambod]

We always ran overhead supplies to mobile classrooms in schools in 6 or 10mm T&E on a catenary! Saved digging up the playground. SWA would be best and ideally underground if possible.

 

[happyhacker]

Steambod implies just and ordinary 2.5/4mm T&E! Is that right?

Another thought with a 16A MCB at the CU end and a RCB in the garage, what detects if the earth becomes disconnected?

 

[1john]

Well only one person suggests that, PVC t&e is not UV stable!

Nothing will detect a disconnected earth, only proper testing.

 

[happyhacker]

Thanks so better cable best then. So what if the earth goes dis. in service - it would seem to be a potential hazard!?

 

[1john]

Yes, you should design the installation to minimise problems. 3 core SWA can provide an additional earth path.

Are there any services in the garage (water / gas)
What type of supply do you have?

 

[holmslaw]

..

 

[ajrobb]

Interesting point about flexing at the walls. Can a catenary be split at the walls (a 'Y' shape) to reduce or distribute this movement?