today's fault

[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

 

[telectrix]

thanks for that. reminded me i've got a 16A type C RCBO in stock. been in the spares box for ages. that'll save a few bob.

 

[UNG]

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

A 13A fuse will carry more than 13A for quite a while before it blows

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.

Must admit never found the need to use C type breakers on a hot tub

 

[telectrix]

trhis afternoon it was pi$$ing down so was not a nice job to check the hot tub rating. rest assured that i will check this before making a final decision on OCPDs.( if the rain ever stops). i know i'll need to install 2.5mm SWA just to be within limits on volt drop,

 

[mickys86]

Just for my 2 pennies worth, I've only installed 1 hot tub and needed a 32 a supply. Because of the volt drop I had to put in 10mm cable!
I'm sure they are all different, it's quite a varied market and not exactly a day to day job

 

[Guitarist]

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.

There are electricians and Electricians. I asked, because the terminology you are using does not sound like someone who has undergone any formal training. My wife is not an electrician, but she knows that you do not get steel in T&E....

 

[trev]

There are electricians and Electricians. I asked, because the terminology you are using does not sound like someone who has undergone any formal training. My wife is not an electrician, but she knows that you do not get steel in T&E....

I think we've scared him off with all this talk of technical stuff like EICRs and testing. I'm thinking he's a DIYer

 

[Engineer54]

What is the hot tub sitting on Tel, ...hopefully not on bare ground or grass?? lol!!
When it stops raining, (..lol!!) check the integral control panel, as most modern hot tubs and Jacuzzis incorporate their own RCD protection.

Personally i wouldn't connect a PME/TNC-S earth to a a hot tub etc that's sitting on concrete, bare ground, grass or tiled concrete base/patio. In such cases go for an earth rod. I think as someone pointed out on another recent thread, that the Reg's call for a local 20 ohm (or lower)) Ra rod to be connected to a PME supplied hot tub/jacuzzi, but i wouldn't recommend that, especially as the users will be walking around with wet and bare feet!!

With TN-S i wouldn't be too bothered, but still prefer to see these tubs sitting on a sturdy built treated hard wooden base and surround...

 

[telectrix]

What is the hot tub sitting on Tel, ...hopefully not on bare ground or grass?? lol!!
When it stops raining, (..lol!!) check the integral control panel, as most modern hot tubs and Jacuzzis incorporate their own RCD protection.

Personally i wouldn't connect a PME/TNC-S earth to a a hot tub etc that's sitting on concrete, bare ground, grass or tiled concrete base/patio. In such cases go for an earth rod. I think as someone pointed out on another recent thread, that the Reg's call for a local 20 ohm (or lower)) Ra rod to be connected to a PME supplied hot tub/jacuzzi, but i wouldn't recommend that, especially as the users will be walking around with wet and bare feet!!

With TN-S i wouldn't be too bothered, but still prefer to see these tubs sitting on a sturdy built treated hard wooden base and surround...

funny, was just thinking about earthing arrangement. it's TNC-S and the hot tub is mounted on wooden decking. from what i saw , there is no integral RCD protection. that came from the plug-on power breaker in the pic. would you recommend using the PME earthing ( as it was ) but banging in a rod at the hot tub as well?

i've read through section 702 as being the nearest reg. reference ( swimming pools and other basins) . can't find any reference in the bgb to hot tubs per se.

 

[tony mc]

I dont know if you looked at this post Tel.

[h=3]hot tubs[/h]

 

[Dave 85]

I think we've scared him off with all this talk of technical stuff like EICRs and testing. I'm thinking he's a DIYer

Well...yes, someone comes here politely asking for a bit of advice and gets bombarded with interrogation and accusations by the usual do gooder, electrical police types. Why should someone who's only ever worked on new builds know what cable was made out of in the 50's. Its not as if they teach it at college.