UK Max distance cable can run overhead without support

[Jonny72]

Hi folks,

I have been through the regs. Have a garage wired from a house. Cable runs overhead at an appropriate height and is suitable cable. The distance in mid air is about 2m. My question is does this need mechanical support by way of a conduit or tray. It does seem a bit excessive for that distance. Cable does not under tension. Any guidance would be helpful.

 

[littlespark]

Catenary wire.

Steel wire suspended under tension (turnbuckles) and fixed securely to the walls.
Electric cable is then tied to the catenary.

The catenary takes all the strain, the cable is simply hanging.

 

[James]

For 2m, I think I would probably use a bit of unistrut tied in at both ends.

 

[Jonny72]

Catenary wire.

Steel wire suspended under tension (turnbuckles) and fixed securely to the walls.
Electric cable is then tied to the catenary.

The catenary takes all the strain, the cable is simply hanging.

Thanks Littespark,

The cable is not SWA looks like HiTuff. Even if the cable is only travelling under 2m will it still require support with Catenary wire?

J

 

[littlespark]

I think the regs put it as “under undue strain” or something.

I take it there’s no risk of this cable being struck by anything passing underneath?

Is burying it not an option?

 

[DefyG]

Just checked the OSG AppD a cable can be unsupported (thermoplastic/HOFR etc) upto - 3m.

It should be no lower than 3.5m to comply though!

Personally I would use a catenary wire though for 2m.

 

[brianmoooore]

Just checked the OSG AppD a cable can be unsupported (thermoplastic/HOFR etc) upto - 3m.

It should be no lower than 3.5m to comply though!

These are the figures I remember from somewhere in the regs, going back to, and including, the 14th edition.
The 3.5m minimum height is for areas not accessible to vehicular traffic. IIRC, the minimum height for where vehicles can access is 4.8m, increasing to 5.1m over crossroads.
Note that the minimum height is for the cable at its lowest point across a span, not the height of the anchorage points.

 

[Jonny72]

I think the regs put it as “under undue strain” or something.

I take it there’s no risk of this cable being struck by anything passing underneath?

Is burying it not an option?

Yes I saw that in regs. No issue with height and unfortunately burying for customer not really an option. It's been this way for many years. I only got involved when my mate who owns a power washing business sprayed the front of the garage penetrating the inside where there are 30A JBs (old style one of which was missing a lid) and tripped the RCD to the kitchen and garage AT DINNER TIME. I went out and made safe. I noted supply to garage was a simple HITUFF cable running about 1.5m. I will likely be back to get lighting running again in garage but don't want. To inherit a pile of issues from how it is supplied. The switches and JBs are likely 30/25 years old. Need replaced anyways but now waterlogged too

 

[littlespark]

Repair and maintenance, you can put it back as it was, as long as it’s safe.

You can of course upgrade items if they need replaced anyway.

This all coming out your mates pocket?

 

[Jonny72]

Repair and maintenance, you can put it back as it was, as long as it’s safe.

You can of course upgrade items if they need replaced anyway.

This all coming out your mates pocket?

See there is the problem. I can put back to way it was. Is it safe, in my opinion NO!! It's wasn't safe before the incident. No Fused Spur protecting the garage from overload. That swinging cable (debatable), 30A JBs (old brown ones) some of which had no covers and switches decades old filled with spider nests. I isolated and got power safely to the CH boiler. Thank God for Wago and their boxes