Earthing conductor also bonding the water...is this allowed?...

[bleach]

The EC appears to be clamped to the water pipe just before going outside to the spike. Was this ever standard? Its a TT with Ze of 36 ohms. Is it best practice to run a separate EC and water bod to MET. (no gas in house).

 

[telectrix]

earthing and bonding conductors should be separate. so, yes. also, with that value of Zs an upfront 100mA delay RCD and 30mA RCDs for all circuits would be advisable.

 

[bleach]

Thanks Tel. All circuits are 30ma rcd'd so is the upfront 100ma delayed needed? How does the 36ohm Ze sound for a TT, is it reasonable? I know the regs say 200ohms etc.

 

[telectrix]

the 100mA is not essential, but would provide back-up for the 30mA units. 36 ohms is a good reading as long as you measured it with the water bond dissed.

 

[Badged01]

As Tel says, highly advisable because with 1 RCD you are kinda putting all your eggs in 1 basket that nothing goes wrong with it. If it does go kaput, none of your circuits will be meeting the disconnections times with an R1+R2 > 36ohms! Atleast with two one should still be functioning ....

 

[kingeri]

By Ze I presume you mean Ra?

I always fit an upfront RCD as well as the 30mA ones on each circuit, simply because RCDs aren't always reliable. Just make sure you don't have a 30mA upfront!

 

[Badged01]

EC appears to be clamped to the water pipe just before going outside to the spike. Was this ever standard?

Never been standard in my book!. I'd actually call it bad practise if for no other reason than you can't actually disconnect the EC for any testing without a parallel path (unless you also disconnect at the water pipe!)

But that said I dont know of a reg that says you can't because ultimately they are all earthed/bonded together.

 

[jibjob]

Lots of TT boards around with 100mA RCD upfront with 30mA often just protecting socket outlets. Telectrix & Kingeri, are you saying that with all circuits protected by say 30mA RCBOs that a 100mA time delay could still be incorporated as back up?

 

[telectrix]

that's exactly what i'm saying. how many RCDs get tested regularly by pressing the test button? very few. then you come along with your posh MFT and test 'em and they don't work, so you press the yellow ---, and they back working. who's to know if they would work if needed to save a life?

 

[jibjob]

that's exactly what i'm saying. how many RCDs get tested regularly by pressing the test button? very few. then you come along with your posh MFT and test 'em and they don't work, so you press the yellow ---, and they back working. who's to know if they would work if needed to save a life?

Fair do's. I've got to change a board following a EICR. Installation is TT but has no RCD protection whatsoever. Looks like it was only installed in last 5/10 years plus an extension was added earlier in the year, no certs or anything. Just the tip of the iceberg to.
Will consider sticking a 100mA time delay upfront, although may enquire into getting it PME'd

 

[Silly Sausage]

Fit a timed contactor which creates a N-E fault every 3 months.
Voila...automatic RCD testing!

 

[Deleted member 72666]

Fit a timed contactor which creates a N-E fault every 3 months.
Voila...automatic RCD testing!

Archy that's not as daft as it sounds! I've often thought about things like this and I just end up putting them to the back of my mind, that and 'built in' smoke/heat detectors for those dodgy connections! All in all I think they could contribute to a safer install, but I'm not sure where to go with these ideas.
Edit:
The quarterly test reminder would have an audio and visual output and not just trip at time out!

 

[Engineer54]

Leave them at the back of your mind, because no one's going to thank you for it!! The operation will be defeated as sure as eggs are eggs, after the second time they operate!! lol!!


Unfortunately householders don't take kindly having to reset every clock/timer device in the house, and there are generally quite a few in a typical household!!

 

[Geordie Spark]

Archy that's not as daft as it sounds! I've often thought about things like this and I just end up putting them to the back of my mind, that and 'built in' smoke/heat detectors for those dodgy connections! All in all I think they could contribute to a safer install, but I'm not sure where to go with these ideas.
Edit:
The quarterly test reminder would have an audio and visual output and not just trip at time out![/QUOTE]

Aye .. it could flash-up a message on the 52" flat screen telly right in the middle of Jeremy Kyle!

 

[PEG]

Good idea,and if me nans in her iron-lung at the time out,she should have put a post-it on the ottaman to remind her...