Is this a safe feed to a shed

[IA76]

Hi

Is this electrical feed to a shed safe?

A double plug socket inside the house has a plug in RCD connected to it. From this RCD a short 2.5mm 3 core rubber flex cable goes through the wall in to a waterproof junction box mounted outside.

Inside the waterproof box the flex connects to 2.5mm armoured cable which runs underground 30m down the garden and then up the shed wall in to a waterproof box from inside which a 2.5mm flex cable goes inside the shed through the wall.

From there it splits off to a double plug socket and a 5a fused switch which goes to a LED light.

Is this safe or can it be improved? The only thing that can't be done at the moment is moving the feed from the plug socket inside the house.

 

[Simon35]

It sounds a bit of a lash-up, but nothing particularly wrong/unsafe with it, IMHO.

Is the cable armouring correctly connected to the earth core in the flexes? Does the SWA have an earth core? How deep is it buried?

 

[IA76]

The cable armour is not connected from what I can see inside the junction boxes. It's just the 3 cores from the SWA connected to the 3 cores of the flex.

I'm not sure of depth for the SWA as it is all under slabs.

 

[Taylortwocities]

The cable armour is not connected from what I can see inside the junction boxes. It's just the 3 cores from the SWA connected to the 3 cores of the flex.

The armour is meant to provide mechanical protection (which yours does) and electrical protection (which yours does not!)
The armour should be connected to earth, ideally at the source (house end)

The idea is that, if there was damage to the cable (like something chopping into it) then the armoured earth whould short to the live conductor and save the life of the mad axeman.

I'm not sure of depth for the SWA as it is all under slabs.

That is OK if the cable remains under the slabs. If the slabs are removed then the cable would need burying, at quite some depth.

I agree, it sounds like a lash-up at the house end.

 

[ban-all-sheds]

It's the sort of thing a DIYer would do, which means it almost certainly was never properly tested. Then there's the lack of knowledge betokened by not earthing the armour. Is the SWA properly glanded at each end?

You ought to get it tested to make sure that it is safe.

If it is to be replaced, bear in mind that when set against the cost of an electrician's time, and the effort of digging a 30m trench, the difference in price between using 2.5mm² SWA (right on the limit for voltage drop even when only a 13A supply) and 10mm² (which would allow a much larger load in the future) is trivial.