Troubleshoot garden electrics

[Milleniumaire]

Had an electrician visit this afternoon. He did lots of testing and found that one of the garden lighting circuits had an issue. This circuit comprises 6 LED flush fitting wall lights and on removing the fronts of of them I was surprised to see lots of soil and an ants nest in one of them! Due to lack of space, each fitting is connected using a plastic connector wrapped in insulation tape, but a couple of the connectors showed signs of deterioration due to damp. So, I plan to clean up the fittings and replace the connectors with something else (wago?) and attempt to make them water resistant with insulation tape. I'll also seal the cable entry gland at the back of the fitting with silicon although there's no sign that this is how moisture is getting into the fitting.

He also told me the double switch in the house used to turn the lights/water pump on/off has a shared neutral and ideally, the switches should be separated out into two fused spurs.

He also pointed out my plastic consumer unit doesn't meet current regulations and the mcb/rcd layout would be better replaced with rcbo's and a surge protector All true, but also very expensive to do!

 

[oldbutnotdead]

PVC tape won't waterproof anything for long.
Might be counter-intuitive but as long as the joints are safely enclosed, don't wrap them- the wrapping just gives a surface for water to cling to and cause problems.
Your plastic CU could not currently be installed but that does not mean it does not meet current regulations - bit naughty of him to angle for that job.
Segregation would be good though, the garage cu mentioned earlier might be worth considering.

 

[Milleniumaire]

As the electrician has suggested I should replace the existing double switch, which shares a neutral, with two switched FCU's I have been wondering if there's a "double socket" sized FCU that includes two fuses and two switches, essentially 2 x switched FCU's in a single "double socket" size. I suspect not as I've not been able to find anything like this online.

The existing double switch is installed in the utility room on an outside wall, so some breeze block chiselling will be required to widen the existing switch plate. If I install two FCU's side by side, I could leave the existing back box (although I may need to make it deeper) and cut out and fit a new back box next to it for the 2nd FCU. The issue with doing this is 1) I need to leave a gap between them so that the remaining strip of plasterboard/plaster is strong enough not to break 2) I'm not sure one of the existing cables would reach the new position, although I assume the electrician could always use connectors to extend the cable from the existing position to the new position?

A "double socket" sized (2 x FCU's) would allow the single to be replaced with a double by chiselling either side of the single. Much easier, although the question of cable length "may" still be an issue.

The electrician can't get back until next week so we agreed I would save some time by doing some of the manual work and fit the new back box myself.

I also wondered if rather than fitting 2 x FCU's with switches, it would be possible to fit 2 x RCD's with switches although, as he explained to me, if they are rated at 30mA as this is the same as the RCD in the CU, it is anybody's guess which would trip first!

 

[Milleniumaire]

Just found the MK grid plus system on Screwfix. They sell a DP control switch and FCU, which can be fitted into a 4-module grid faceplate + grid plate.

I have no idea if it would be possible to wire the DP switch and the FCU together to give a switched FCU. If it was, then fitting 2 x FCU's and 2 x DP switches into the 4 module plate might be just what I was looking for!

 

[Milleniumaire]

In the end I purchased 2 x MK grid plus Double Pole switches, a 2 module grid plate and faceplate. This was a straight replacement for the double switch plate that was installed and provided double pole switching instead of the standard single pole switching. I also replaced the metal backbox with a 47mm deep back box to provide more room for the cables and connectors.

As far as I'm aware, because this was a replacement and no new wiring/circuit was installed I was okay doing this myself.

 

[ericmark]

A number of issues, cost I lost two freezers full of food due to a RCD trip, compared with cost to restock fitting RCBO's is cheap.

As to replacing plastic CU with metal, only if existing plastic can't be used, due to location etc.

The regulations are not retrospective, however in the main they are to increase safety, so one needs to assess the risks.

Two ways to do outdoor electrics one water proof, two ensure water can run out again.

It depends how damp the area is, woodland is very damp, 4 foot up on side of house wall is not, so one has to decide what is appropate for location.

Air expands and contracts, so it can suck in water, better filled with petroleum jelly as will not cause water to be sucked in the same way as air.

Some thing like a bird box so connections off the ground is good.

But you must design the electrics for the environment.

 

[Milleniumaire]

Having cleaned out each of the 6 flush fitting wall lights and replaced the connectors with Wago connectors it seems these lights will now work while the water feature pump is turned on i.e. the RCD doesn't trip. At the end of the 6 wall lights is an additional IP66 BG junction box connecting the wall lighting circuit to a Saxby Atlantis Spike IP65 stainless steel garden light and this also switches on when the wall lights are on, so is also working okay i.e. doesn't trip the RCD.

However, another part of the garden lighting circuit includes another Saxby Atlantis Spike light which lights up the water feature and when this is connected it trips the RCD whether the pump is on or not and even when this is the ONLY light fitting connected to the garden wiring.

So, I replaced this water feature light fitting with the one connected to the wall lights and nothing tripped, even when the wall lights + water feature light and the pump were on. Switched back to the original water feature light fitting and it tripped. This suggests there is therefore something wrong with the water feature light fitting or the water feature light fitting cable.

I now have the wall lights, the (replacement) water feature Saxty spike light and the pump working without tripping. There are two more lighting circuits that I haven't yet connected up and the electrician is back tomorrow so hopefully he will test these, although I plan to try them tonight after I've finished work.

I'll also ask if he can test the original water feature light fitting that I now know was causing the RCD to trip. It will be interesting to see if there is a detectable fault with this light fitting.