today's fault

[telectrix]

RCD tripped. narrowed down to SWA feeding hot tub. never seen SWA connected like this before. armour not earthed anywhere. was supposedly professionally installed. the pic shows a 30mA plug-in power breaker RCD, the type you'd fit to a lawn mower cable!



disconnected both ends and IR tested SWA . L/E 0.04 Meg. N/E 0.23 Meg. 40m of SWA, partly buried. half way down had been repaired? with choc block and tape.

so , it's quote for new SWA, glands, ad. box, correct installation. what i'm not happy with is that it's fed from the garage sub-main which is in turn fed from the house RCD in a split board, so a fault will take out all in the house except lighting. now, i've not done any work on hot tubs, but my thinking is to feed the garage sub. from the non protected side of the house ( it's fed in SWA ) and then fit RCBO in the sub. to cover the garage socket ( just a fridge/freezer) and a 13A FCU to feed the SWA to the hot tub. anyone see a flaw in this? worked out the VD at 13A to be 9.5V using 40m of 2.5mm SWA.

 

[mickys86]

shhh, it's not my thumb. it's my big toe.

My first reaction to the pic was that it can't be your big toe! Haha

 

[Sam Pringle]

I wonder if anyone can help me..? I have installed a new RCD board in a house that has wiring system of different ages (the guy was strongly opposed on the idea of a full rewire) the previous board being a random assortment of big old fused isolators for each circuit under his stairs. All the circuits held fine apart from the 3 rings. One of the legs for downstairs ring was wired in steel, could this cause a trip? Or am I likely looking for earth faults not picked up by his previous medieval protection?

New to this so apologies if this is in the wrong place, and thanks in advance for any help...

 

[trev]

You should have carried out an EICR before replacing the CU mate. This would have identified any faults beforehand.
When you say wired in steel what do you mean by that?
What test results were obtained for the RFCs?

 

[Des 56]

a new RCD board in a house that has wiring system of different ages ​

​

The only correlation between them that I can see, both the wiring system and tels big toe, both are ancient

 

[Guitarist]

I wonder if anyone can help me..? I have installed a new RCD board in a house that has wiring system of different ages (the guy was strongly opposed on the idea of a full rewire) the previous board being a random assortment of big old fused isolators for each circuit under his stairs. All the circuits held fine apart from the 3 rings. One of the legs for downstairs ring was wired in steel, could this cause a trip? Or am I likely looking for earth faults not picked up by his previous medieval protection?

New to this so apologies if this is in the wrong place, and thanks in advance for any help...

You would be better off starting a new thread for this one. Btw, are you an electrician?

 

[Sam Pringle]

Steel instead of copper in the t&e, I know now I probably should have tested first and to be honest I agreed to do the job as a favour for a friend and I'm starting to regret it, and yes I am an electrician I have spent my seven years on new build schools so my domestic fault finding ability is non existent.

 

[Des 56]

Steel instead of copper in the t&e,

You may find the conductor would be tinned copper or alluminium rather than steel

 

[trev]

Fault finding in cables is fault finding in cables no matter where you carry it out mate, a methodical approach is all thats needed.
Steel T&E is something I have never seen in 29 years since I qualified, are you absolutely sure about that?
Once again, what test results did you get from your RFCs?

 

[Des 56]

downstairs ring was wired in steel, could this cause a trip
​

?


Please explain your train of thought on this statement

​

 

[telectrix]

could trip over it, i suppose.

 

[telectrix]

@ OP. try a magnet on the cable. bet it's tinned copper or alli. then you need to IR test each circuit, check for crossed/shared neutrals. and most important, make sure you've not crossed neutrals into wron bar in CU and check manufacturers tails. they have been known to be wired wrong in the sweat shop. (sorry, far eastern technology factory)

 

[trev]

Just out of interest Sam, what tests did you carry out during your CU change? Have you notified it? What certification did you issue?
What tester are you using?

 

[UNG]

RCD tripped. narrowed down to SWA feeding hot tub. never seen SWA connected like this before. armour not earthed anywhere. was supposedly professionally installed. the pic shows a 30mA plug-in power breaker RCD, the type you'd fit to a lawn mower cable!

View attachment 12828

disconnected both ends and IR tested SWA . L/E 0.04 Meg. N/E 0.23 Meg. 40m of SWA, partly buried. half way down had been repaired? with choc block and tape.

so , it's quote for new SWA, glands, ad. box, correct installation. what i'm not happy with is that it's fed from the garage sub-main which is in turn fed from the house RCD in a split board, so a fault will take out all in the house except lighting. now, i've not done any work on hot tubs, but my thinking is to feed the garage sub. from the non protected side of the house ( it's fed in SWA ) and then fit RCBO in the sub. to cover the garage socket ( just a fridge/freezer) and a 13A FCU to feed the SWA to the hot tub. anyone see a flaw in this? worked out the VD at 13A to be 9.5V using 40m of 2.5mm SWA.

13A sounds a bit low for a hot tub all the tubs I've worked on have been 20A - 30A supply to cope with the heater(s) and the pumps. Have you checked the supply requirements of the tub as given the poor original install I would not take anything for granted

 

[telectrix]

thought that at first, but it has been running on a 13A 1362 quite happily before the cable failed.

 

[Sav]

RCD tripped. narrowed down to SWA feeding hot tub. never seen SWA connected like this before. armour not earthed anywhere. was supposedly professionally installed. the pic shows a 30mA plug-in power breaker RCD, the type you'd fit to a lawn mower cable!

View attachment 12828

disconnected both ends and IR tested SWA . L/E 0.04 Meg. N/E 0.23 Meg. 40m of SWA, partly buried. half way down had been repaired? with choc block and tape.

so , it's quote for new SWA, glands, ad. box, correct installation. what i'm not happy with is that it's fed from the garage sub-main which is in turn fed from the house RCD in a split board, so a fault will take out all in the house except lighting. now, i've not done any work on hot tubs, but my thinking is to feed the garage sub. from the non protected side of the house ( it's fed in SWA ) and then fit RCBO in the sub. to cover the garage socket ( just a fridge/freezer) and a 13A FCU to feed the SWA to the hot tub. anyone see a flaw in this? worked out the VD at 13A to be 9.5V using 40m of 2.5mm SWA.

Hi Telectrix,

I wired a hot tub not too long ago and went by the supplier spec.
They requested a C type 20A mcb, due to start up surge. Also, i wired the supply from the C type mcb in 2.5 swa, into an isolator which also had a commando socket outlet. The company then hooked up the hot tub from their end into the commando socket.

If you do put an RCBO, make sure its C type, as you may have problems on start up.

Hope this helps,
Sav