Earthing a replacement Triton shower unit - please advise

[mikeyw]

Hi,

I'm in the process of replacing a Triton opal shower with a Triton ivory 4. I assumed the electrics woiuld be a simple swap over but the earthing on the 2 showers is very different.

On the new shower it simply seems to require the standard earth cable connecting along with the live and neutral into the terminal block whereas the older unit was earthed very differently including to the water inlet pipe

Can you confirm no additional earthing is needed on the replacement unit ?

Opal :- (ignore the electrical tape was just tping it up while disconnecting it all)

Ivory :-

Thought it best to check no additional earthing was needed on the new unit. Instructions dont seem to indicate so


Thanks in advance,
Mike.

 

[viewer]

Have a look at the mega thread about plumbers; it will give you the thumbs up for not connecting to the water inlet.

 

[PrenticeBoyofDerry]

I would check this out mickeyw:
//www.diynot.com/wiki/electrics:speclcn:supbond17th

 

[mikeyw]

I decided to go with the single earth - surely Triton would have stipulated if the additional earthing was needed.

It's working fine

 

[bernardgreen]

You need to verify that the CPC ( earth wire ) in the supply is connected to the earth bar in the consumer unit.

No point ( and a serious hazard ) to rely on an earth wire that isn't connected at the other or has a break in it.

I have recently seen an isolator switch where the earth terminal had not been tightened. Possibly tested OK at low test current but what would it have done with a high fault current. ( OK I know the RCD would have tripped but not all showers have RCDs "protecting" the circuit. )

 

[PrenticeBoyofDerry]

surely Triton would have stipulated if the additional earthing was needed.

I guess the installation manual, stipulated compliance to IEE wiring regulations?

 

[Lectrician]

The cable to the inlet pipe was likely supplementary equipotential bonding. This may not be required if ALL your circuits in the bathroom are RCD protected.

And just because something works does not mean it's safe

I once had a phone call from someone who asked if they could connect just one of the earths behind the shower switch to the switch itself, as one was two short (they were replacing the switch). In there mind, if atleast one was connected, everything would be fine - They could not see that continuity would be lost to the shower!

 

[PrenticeBoyofDerry]

Under the 17th edition regulations (BS7671:2008) supplementary bonding in a bathroom may be omitted where certain criteria are met.

*All circuits comply with the requirements for disconnection times
*All circuits are RCD protected by a 30mA device maximum
*All extraneous conductive parts in the location are effectively connected to the protective equipotential bonding.

 

[ban-all-sheds]

I decided to go with the single earth - surely Triton would have stipulated if the additional earthing was needed.

That connection to the water pipe is not an earth, it's supplementary equipotential bonding.

If it was needed before it is needed now.

You should read up on it - you've decided that you can play the role of a competent electrician, so you need to actually be competent.

• //www.diynot.com/wiki/electrics:supplementary-equipotential-bonding
• http://www.tlc-direct.co.uk/Book/7.2.1.htm
• http://electrical.theiet.org/wiring-matters/27/complete.cfm

 

[bernardgreen]

Under the 17th edition regulations (BS7671:2008) supplementary bonding in a bathroom may be omitted where certain criteria are met.

At least it says may be omitted and does not absolute ban the bonding.

Personally I would add the bond as a single fault ( loss of continuity ) in the CPC to the shower could create a hazard if there is no continuity inside the shower between the feed pipe and the ( assumed ) earthed heater tank.

If the heater tank was not connected to "earth" then its potential due to capacitive coupling would be arround 120 volts. If the feed water pipe was touchable and via main bonding was connected to "earth" there is a hazard.

The capacitive coupling in the heater tank is considerable higher than inter conductor coupling in cables and is probably enough to create a significant current if the tanks or water from it somehow came in contact with someone who had a second point of contact to earth via a bonded pipe.

 

[viewer]

I decided to go with the single earth - surely Triton would have stipulated if the additional earthing was needed.

That connection to the water pipe is not an earth, it's supplementary equipotential bonding.

If it was needed before it is needed now.

You should read up on it - you've decided that you can play the role of a competent electrician, so you need to actually be competent.

• //www.diynot.com/wiki/electrics:supplementary-equipotential-bonding
• http://www.tlc-direct.co.uk/Book/7.2.1.htm
• http://electrical.theiet.org/wiring-matters/27/complete.cfm

Oh NO, please tell me BAS is wrong or I'll cut my throat!!
Have I got this wrong?
The water pipe may need bonding; not questioned. The 'old' wiring connected the water pipe to the earth terminal on the shower. Therefore the pipe was earthed and not bonded.

 

[EFLImpudence]

Oh NO

Bonding, when required should connect, in a location, simultaneously accessible extraneous and exposed conductive parts and/to the CPCs of circuits of the location.

You are allowed to use the extraneous parts as bonding.

So, one way of connecting, say, the hot water pipe under the basin to the shower CPC (shower having no exposed conductive parts) would be by connecting it (hwp) to the cold water pipe which runs to the shower and then this short bond from cwp to shower CPC - assuming the route isn't long enough to negate the benefit of the bond.

Remember, only parts which are themselves earthed need bonding.
So, the shower cwp is already earthed by the ground (and so has to be main bonded) therefore this short length of g/y wire is bonding the pipe to the shower CPC - not earthed by it.


Assuming it is done correctly, of course. It may be a mistake.

 

[RF Lighting]

Best get cutting.

The connection between the pipe and the earth terminal is part of the bonding arrangement.

The purpose is to keep both parts (and what ever else is included within the bonding) at the same potential during a fault. The fact that one of the parts is an earth terminal and will be at earth potential during normal conditions is incidental.

 

[viewer]

Thanks guys. Another piece of the jigsaw; I hadn't realised that bonding can use the same connection point as the CPC when this is used as a part of the system of bonding (when both are required to be at earth potential). It does make sense when explained.
Razor sharpening time