On Saturday, 9 September 2017 13:28:12 UTC+1, John Rumm wrote:
On 09/09/2017 12:14, tabbypurr wrote:
On Monday, 4 September 2017 10:22:49 UTC+1, John Rumm wrote:
On 04/09/2017 08:31, wrote:

Thanks all. Especially for the shaver socket tip. I had
previously assumed the only difference between them and sockets
was dual voltage

Note that there are two types of shaver socket. The transformer
based ones that are suitable for bathrooms (and usually offer dual
voltage) and the non transformer based ones that are not suitable
for bathrooms.

The shaver socket on the wall would work best but we have a
small splashback and then huge mirror above the sinks so only
place would be between the sinks and just off worktop level which
seems a bit dodgy to me? So...

Looks like best option is shaver sockets in the cupboard below
the sinks.

Another option is a shaver socket built into an over mirror based
light fitting.

In terms of the spa bath then I guess running a feed to the
cupboard and installing a ipx4 or better switch to switch it off
(or maybe one of those dual pole things that we use to isolate
the extractor fan) and then run this to the bath with a
waterproof junction box under the bath for extra safety.

Sound ok?

Yup you can have a remote switch for the bath feed if you want.
You could place the switched fused connection unit in the cupboard,
and then have that feed either a junction box or flex outlet the
bath if you want.

So... Last 2 questions. 1. The bath has the metal framing
connected to one of the motors via an earth lead. However the
earth from the mains connection doesn't seem to be connected to
it. I would have expected to see an earth coming out of the
junction box to connect to the frame. Any thoughts?

I am not totally clear on exactly what setup you have here, so I
will answer the more general questions...

If the motor units are double insulated (has the double square
logo[1]) then they do not need an earth connection. However you
would normally wire the connection point such that one is available
in case the motor were changed later and the new one needed one. If
needs be, the earth connection can be made of in a spare non
connected terminal block.

[1] http://wiki.diyfaq.org.uk/index.php/...l_Glossary#1-9

If the motors do require an earth, then the earth of the circuit
feeding them should be included into the supplementary bonding in
the bathroom.

The metal frame of the bath itself is typically not connected to
anything outside of the room itself, and hence not capable of
introducing any potential into the room. As a result it does not
need including in the EQ bonding.

See http://wiki.diyfaq.org.uk/index.php/...ng_and_Bonding

2. I plan to cut into the upstairs ring main to feed this
bathroom. Not a spur buy essentially extending the ring. Any
issues with this?

No that's fine. Note the comments above about including its earth
in the bonding for the room.

Connecting the bath frame to the motor frame does make it able to
introduce 240v in case of fault. I would earth it & feed it from an
RCD or include it in equipotential bonding.

If the motor is class I, then its supply earth should be included in the
bonding, and the motor casing itself does not need independent
connection.

If its class II, then its case is not an extraneous
conductive path,

Whether the motor can conduct to the bath or water depends on construction details. Class 2 certainly does not preclude it. Class 2 construction is no more a panacea than the other approaches.

and so bonding the bath would actually increase the
risk rather than lower it.

bonding it to what? bathroom-wide equipotential bonding or the motor case?


NT