Hello

I have just installed a bathroom fan which is on a timer...

Problem is...

fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is tripping..

I take it I now have to connect the lighting ring to the RCB??

"PhilÅ" wrote:
Hello

I have just installed a bathroom fan which is on a timer...

Problem is...

fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is tripping..

I take it I now have to connect the lighting ring to the RCB??

You should have taken all the feeds to the bathroom fan from a single
circuit, I'm pretty sure your wiring contravenes the IEE regs and, as
you've discovered, it doesn't work either!

--
Chris Green

wrote in message ...
"PhilÅ" wrote:
Hello

I have just installed a bathroom fan which is on a timer...

Problem is...

fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is
tripping..

I take it I now have to connect the lighting ring to the RCB??

You should have taken all the feeds to the bathroom fan from a single
circuit, I'm pretty sure your wiring contravenes the IEE regs and, as
you've discovered, it doesn't work either!

--
Chris Green

Chris

If I take them from the mains ring (common) then this contravenes IEE is
dangerous, as the lighting ring could be switched off and the light live, so
I am to take it all from the lighting ring...

"PhilÅ" wrote in message
...

wrote in message
...
"PhilÅ" wrote:
Hello

I have just installed a bathroom fan which is on a timer...

Problem is...

fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is
tripping..

I take it I now have to connect the lighting ring to the RCB??

You should have taken all the feeds to the bathroom fan from a single
circuit, I'm pretty sure your wiring contravenes the IEE regs and, as
you've discovered, it doesn't work either!

--
Chris Green

Chris

If I take them from the mains ring (common) then this contravenes IEE is
dangerous, as the lighting ring could be switched off and the light live,
so
I am to take it all from the lighting ring...



I don't want to sound offensive I would suggest you get professional help
in.

You should never take a live feed of one circuit and a effectively a neutral
of another. If your case there is no longer a neutral current so there'll
immediately be an imbalance of current in the live and neutral flowing
through the RCD. It will trip as soon as you put any load on any circuit.

"Fred" wrote in message
...

"PhilÅ" wrote in message
...

wrote in message
...
"PhilÅ" wrote:
Hello

I have just installed a bathroom fan which is on a timer...

Problem is...

fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is
tripping..

I take it I now have to connect the lighting ring to the RCB??

You should have taken all the feeds to the bathroom fan from a single
circuit, I'm pretty sure your wiring contravenes the IEE regs and, as
you've discovered, it doesn't work either!

--
Chris Green

Chris

If I take them from the mains ring (common) then this contravenes IEE is
dangerous, as the lighting ring could be switched off and the light live,
so
I am to take it all from the lighting ring...



I don't want to sound offensive I would suggest you get professional help
in.

You should never take a live feed of one circuit and a effectively a
neutral
of another. If your case there is no longer a neutral current so there'll
immediately be an imbalance of current in the live and neutral flowing
through the RCD. It will trip as soon as you put any load on any circuit.



fairy muff, I will forget the timer option, and just connect the fan up to
the lighting thingy..

Cheers

fairy muff, I will forget the timer option, and just connect the fan up to
the lighting thingy..

Er, you can run the timer off the lighting circuit. The whole thing should
be entirely off the lighting circuit.

You need to take the live, switched live and neutral from the ceiling
rose/junction box. Then pass each of these through a 3 pole isolator switch
and into the fan.

Christian.

PhilÅ wrote:
"Fred" wrote in message
...

"PhilÅ" wrote in message
...

wrote in message

...

"PhilÅ" wrote:

Hello

I have just installed a bathroom fan which is on a timer...

Problem is...

fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is
tripping..

I take it I now have to connect the lighting ring to the RCB??


You should have taken all the feeds to the bathroom fan from a single
circuit, I'm pretty sure your wiring contravenes the IEE regs and, as
you've discovered, it doesn't work either!

--
Chris Green

Chris

If I take them from the mains ring (common) then this contravenes IEE is
dangerous, as the lighting ring could be switched off and the light live,

so

I am to take it all from the lighting ring...



I don't want to sound offensive I would suggest you get professional help
in.

You should never take a live feed of one circuit and a effectively a
neutral
of another. If your case there is no longer a neutral current so there'll
immediately be an imbalance of current in the live and neutral flowing
through the RCD. It will trip as soon as you put any load on any circuit.




fairy muff, I will forget the timer option, and just connect the fan up to
the lighting thingy..

Cheers


Can you run a 3 core and earth to the fan? One core switched with the
bulb, an other to provide power for the timed run with the third as
neutral. This is how they are intended to work, but with the changes to
bathroom regs, I'm not sure what would be required any more.

Andrew

PhilÅ wrote:


You should never take a live feed of one circuit and a effectively a
neutral of another.

Dead right. From Phil's description he's in fact got live feeds from two
different circuits - a perm-live wrongly taken from the ring, and a
switched-live ("trigger" for the fan's run-on timer) from the lighting
circuit (specifically, I'd guess, from the bathroom lamholder's
(switched) live terminal).

Fixing this to be Right is not so hard. You don't need to


.... forget the timer option, and just connect the fan up to
the lighting thingy..


Rather, you need to forget the ring circuit altogether as your source of
perm-live. Run a triple-and-earth cable from the Appropriate Place on
your lighting circuit. That T&E wants to carry the (lighting circuit)
Permanent Live, the bathroom light's Switched Live, the (lighting
circuit) Neutral, and the (lighting circuit) Earth. It wants to go via a
3-pole fan isolator (made for the job, switching all three non-earth
conductors, you see) and on to the relevant terminals of the fan.

OK, but what's this Appropriate Place? That depends on how your bathroom
light is wired. If it's the loop-in system, all four connections are
already present at the ceiling rose - N (black wires at one edge),
perm-L (in the middle), switched-L (at the other edge) and an E
terminal. Though the loop-in arrangement is the most common system on
newer properties, ceiling roses are not usual in new-build bathrooms
(usually an fitting is used which is flush to the ceiling). In this case
it's most likely that there's a junction box in the loft above the
bathroom, which becomes the Appropriate Place, as it'll bring together
the N, perm-L, switched-L, and E in one neat place. There's a third
'standard' possibility where all wiring is done at the switches and
lighting points, with the extra way or two sometimes needed being made
using bits of 'chocolate block'; in this case you may not end up with
one Appropriate Place, but would have to use two T&E runs to your 3-way
isolator to get all 4 connections.

In summary: DON'T mix 'final' circuits: make all your connections ONLY
into the lighting circuit. DO use a bathroom fan isolator (and position
it out of reach of anyone using, incl. standing in, the bath/shower). IF
you're sure you can safely bring both switched-L and perm-L to the
isolator, do that; if not, go for your 'forget the timer, just use the
lighting point' simplification. IF you're in any doubt, get a sparks in:
no point frying yourself or your Lurved Ones (or even a visitor!) for
the sake of 80 notes...

Stefek

"PhilÅ" wrote:

I take it I now have to connect the lighting ring to the RCB??

You should have taken all the feeds to the bathroom fan from a single
circuit, I'm pretty sure your wiring contravenes the IEE regs and, as
you've discovered, it doesn't work either!

--
Chris Green

Chris

If I take them from the mains ring (common) then this contravenes IEE is
dangerous, as the lighting ring could be switched off and the light live, so
I am to take it all from the lighting ring...

Yes, I think that's the normal way of doing things, all from the
lighting circuit.

--
Chris Green

In article ,
PhilÅ wrote:
fixed 240 V is from a 3A spur of the a socket ring on the RCB.

the light feed is not on the RCB.

So when connected up the neutrals are now common and the RCB is
tripping..

Yup. They're good at showing up stupid things. ;-)

--
*One nice thing about egotists: they don't talk about other people.

Dave Plowman London SW
To e-mail, change noise into sound.