About 12 years ago when I installed my electric shower I did all the plumbing
and cabling and got Scottish power ( It was SSEB then ) to do the final
connection .The guy came and did the job but commented to add an additonal earth
cable from the shower to the CH radiator and then back to the Scottish Power
earth terminal beside the consumer unit . This I did and it has remained that
way ever since .
I have just replaced my shower with a 10.5 one and was unable to get the circuit
earth and this extra earth cable in to the cable connector ( The previous shower
had a stud and nut connection arrangement ) so I have left out the additional
earth between the earth and the radiator . It set me thinking why this extra
earth was necessary in the first place and also about the earth from the
radiator as well. Should I leave things as they were before ( Using thinner
earth cable betweeen shower and radiator to allow it to get in to the connector)
or what does anyone suggest ?
On Sat, 30 Dec 2006 20:23:06 GMT, Harry Bloomfield
Ok..so it seems you are saying I should return the arrangement to how it was
before with the shower being connected to the radiator then to the Scottish
Power earth point but there is the confusion caused by the part plastic ,part
copper plumbing to the bath/basin /toilet .
And all class I and II electrical equipment. No need to bond taps though.
Although supplementary bonding will almost certainly result in the bonding
cable been at earth voltage due to a light fitting, shower or a radiator etc
there is no need to take the cable back to the earth busbar in the CU.
Generally the smallest bonding cable you can use is 4mm^2
You need to ensure that the equipotential bonding in the room is
present, however there is no need for a discrete connection back to the
CUs main earth terminal (although since you would usually include the
CPCs (i.e. earth wires) of any circuits delivering power into the
bathroom in the equipotential bonding then you will in effect get this
via a fortuitous route)
this may be of some help
http://www.niceic.org.uk/downloads/Pocket%20Guide%202.pdf you need to
connect all earth terminals in the zones together along with metal pipe
work, metal bath and any radiator fed with metal pipes, dont run cable back
to mains, this isnt about introducing earth potential but creating a
faradays cage so all metal work will be at same potential. If your in
England this is under part p of building regs and is a legal requirement to
notify the local authority so is swapping a shower in a bathroom.....is your
cable and pull switch up to the job (current) of the new shower?
I am not in England .
The new shower pull switch and cable (10mm) are both suitable for the job .
All I was really wanting to know was about the instruction all those years ago
to add in a seperate earth from shower to radiator to Sc Powers earth connection
. The shower obviously has an earth connection via the supply cable so I
couldn't see why an "extra" earth was necessary ( excluding the radiator as
that's a seperate issue ).
Thx for the link .
I'll probably get a sparks in after the hols to check over the bonding as it's
all Greeek to me despite having read about it and the use of part copper part
plastic just confuses the issue .
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