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
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
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.
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
I think I might do that??.
Have to find suitable cable.
The fan does not have any place for a earth??.
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
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
I think the best advice was to let someone with a clue have a look, IME people without one normally make other (possibly lethal) errors as well....
Yes, I think that's the normal way of doing things, all from the lighting circuit.
On Thu, 20 Jan 2005 18:13:07 -0000, "PhilÅ" strung together this:
Leave it alone, get someone in who knows what they are doing. You are obviously a danger to yourself and others.
If this was designed with flat T+E, wouldn't it have a parking connector for the earth?
many don't since they are double insulated and expect to be fed from a flex connected to an adjacent flex outlet or FCU...
Yup. They're good at showing up stupid things. ;-)
I would argue that if the fan itself is actually in the loft (i.e. it is a ducted fan) then having the isolater there next to it is logical since it is within ready control of the person working on the fan.
Can the isolator be in the loft above the ceiling ( ie next to the fan)?
Martin
Strictly speaking, no: as a motor isolator, it's supposed to be accessible and if not within ready control of whoever's working on the dreadfully dangereous arm-chopping motor, able to be locked off.
Still, 'strict' conformance should (in my way of thinking) be weighed against rationality. If something really is a serious limb- or life-endangering fixed motor, and needs frequent mechanical maintenance (blade-changing, filter-changing, whatever) I'd do my nut if it wasn't reliably isolatable. But for a domestic bathroom fan, especially if the loft's accessible (fixed loft ladder, light, and boards), I can't see it being seriously, dangerously wrong to fit the isolator above the ceiling, especially if you can put a little label in/near the visible part of the fan in the bathroom to describe the isolator's location.
Now waiting for the wrath of NICEIC to descend...
Stefek
In fact it could be argued that that it's not just logical but would be the correct location for the 'motor isolator' - if the isolator isn't next [1] to the motor unit then the isolator need either a lock or removable link.
[1] ie. in the same room.
No question that you're right. My thoughts were supposed to refer to the fan-through-the-wall or similar case, where the motor's in the bathroom. That's the more arguable case, where the isolator isn't so readily operable and observable (or, without local knowledge, even locatable!) by whoever's doing the maintenance; I call it 'arguable' rather'n 'forbidden' since, in the domestic case, there won't be other people trooping up into the loft to switch the isolator back on, and if it's accessible in practice, I can't see it being a gross violation.
But smarter still, and quite common practice, is to put the isolator just outside the bathroom, right up by the ceiling - out of reach of casual switching, more accessible than up in th'loft.
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