SWA and damp.

[La Poste]

Greetings.

My neighbour has a barn that needs doing but also this.
He has just had a major extension done, a lot of work and a bit of it sub standard.
He didn't realise at the time that the guy living next door to him IE me could have probably done it better. :stuart:
Anyway he has had a lot of garden lights fitted.
A 1.5mm SWA cable runs from the house down to the bottom of his garden.
It terminates in a splash proof adaptable box and then feeds various lighting circuits.

There is a stream at the bottom of his garden and the sparky who fitted all the lights down there probably did
not realise the area was prone to flooding, I mean it gets completely submerged.
This outside circuit is wired to the fuse board inside the house and is attached to an RCD that also supplies a lot of other circuits.
Of course whenever he tries to switch his outside lights on half of his house goes dark.

I was having a look today and testing, I isolated the SWA that feeds the lights and started to measure it.
The IR results I got for L-E and N-E were about 9 Mohms but when I measured the L-N I got 0 MOhms.
I then transferred to Ohms and got a reading of 10.7 K ohms which then crept up to 20 K ohms.
You can see by my pictures.

The cable looked dry at both ends, maybe just a bit damp but I wondering why it would be that my readings are so low between L-N.
Is this just damp or has the cable been damaged in some way by all the gardening work that has gone on on top
of it.

I also went to see another guy who wanted outside lights fitted, a different customer.
He told me that his existing supply, a 2.5 SWA had a buried joint in the ground, a torpedo joint.
I measured that cable and found the IR between L-N started at 0.30 Mohms and then gradually crept up to 2.5 Mohmns.
I am not sure whether to condemn this cable and lay a new one.

So my question is really what is acceptable for SWA and how much do they vary due to damp.
Once we get a bit of juice running through them will this IR figure increase dramatically?
It's one of those areas that are grey, not black or white and maybe with a bit more experience
I could make an educated guess but right now I am not sure.

Any comments welcome.
Thanks.

 

[alli]

There are these that don't need sealing compound but I have never tried them:

View attachment 11732View attachment 11733

Adding the flex could be an issue but maybe I could re-wire the lights in SWA also.

Thats the boxes, they do an above ground box as well as a below ground version.
I've used a plastic compresion/pack gland for flex with no problems at all.
The boxes come with fittings to terminate SWA cable, I don't know why but I've always used SWA glands with them. In the second photo you can see a s/steel bush, this can be unscrewed and allows a 20mm SWA gland or pack gland to be screwed in.

 

[Engineer54]

There are these that don't need sealing compound but I have never tried them:

View attachment 11732View attachment 11733

Adding the flex could be an issue but maybe I could re-wire the lights in SWA also.

I think i've been using the Wiska box name as a generic name given to such boxes. Though i'm pretty sure Wiska do metal versions of there plastic models. But it certainly looks like it's the Pratley type boxes shown here, that i've been referring too in my posts....

One thing i would never use, and wouldn't allow there use on my projects, ...and that's those ''screwit'' type connectors shown in photo 1. Most of the electrical cause of fires in the USA are down to these obsolete screw on connectors that the Yanks love, and you'll find them in every single switch and outlet box, as there standard accessories only allow for single wire connection (screw wrap or push-fit), so it's generally joints and a tail to the accessory.....

 

[La Poste]

I guess the ultimate box would be a Pratley with push fit Wago's inside all soaked in resin.

The armouring continuity would be guaranteed by the metal structure of the box when glanded correctly.

Sounds good to me.

 

[alli]

If your going to fill it with resin, I wouldn't bother wasting your money on a Pratley type box but buy the cheapest adaptable box you can.

If you wanted belt and braces without using resin, look at TLC website for weatherproof compound, you could use this to encase your connection and keep them watertight even if the box or glands fail.

 

[edrobbo8]

You can also get the weatherproof insulating gel, which prevents any short between L-N and L+N-E, works well and you can get into it again without the hassle you have with resin!

 

[Strima]

Wiska boxes and magic gel on this page...

Anyone used this gel stuff? Any good?

Got a job coming up soon, buried garden lights always flooding due to a high water table and clay base, swapping for light bollards but using the existing buried SWA, subject to testing. Originally installed by a builder who has tried various times to seal the lamps with silicone sealer to no avail.

Hopefully can get away with moving the lamps 500mm to the right then using the existing holes as earth pits for the junctions.

 

[La Poste]

They have all sorts of joints here.

All kinds of different connectors and I haven't tried any of them:

Paige Products