Fan

[timmyquick]

Does any one know where a timed overrun fan can be bought which does not require a 3 amp fuse to make wiring simpler. I have checked the wiring on my sisters house which has a timed fan working through the pull cord switch in the bathroom as does my mums ( which just passed electrical inspection from council) but neither have been fused down to 3 amp. Yet every fan i have seen say they need to be connected to a FCU at 3 amp which is impractical. Or is it allowed within the regs to fuse the feed to the ceiling rose as well thus the light being on a 3 amp fuse as well. I need to get this done right as when the building inspector sees this working he will issue completion certificate. But if i don't get this done by tuesday he says that he is going to do me for all electrics and plumbing after new year.

What method do electricians normally use when in this situation?

There must be an acceptable method as how do new build homes go on?

Forgot to mention on the house which just passed inspection there is no fan isolation yet it passed inspection?

 

[comms]

The fan should be protected by a 3 amp fcu/fuse, if a fault occurs with the fan the 3amp will blow before the lighting circuit protective device, without the 3amp fuse you've lost the lights when the protective device trips. You should also have a fan isolation switch fitted to the circuit to cover switching off for mechanical maintenance or emergency isolation switching (rotating equipment).

lightcircuit - fcu - isolation switch - fan.

 

[pipme]

Electrics 'for reference p.2' Scroll down for two dwgs using fuse, one without.
See my problem :- //www.diynot.com/forums/viewtopic.php?t=11770&highlight=fuse
With good suggestion for fusing.
P

 

[timmyquick]

thanks Pipme.

I have seen that, how do you achieve the switched live after the SFCU? do you use single cores or twin and earth?. If you use twin & earth for switched live after SFCU what do you do with the neutral? Could someone please go into more detail.

Would this also be acceptable?

Feed from rose into SFCU with twin & earth, then from SFCU to Timed overrun Fan. Then twin & earth from fan with the red wire connected to permanent live in fan. Use black wire sleeved with red connected to switched live in fan, then taking this twin & earth to a DP pull cord in bathroom, replacing old pull cord switch. Also is a DP pull cord allowed to be used for 2 live feeds? as i have seen in this forum suggestions of using a shower DP swith instead and surly you cant stick a live wire into that as they clearly have marked connections for 1 live and 1 neutral. Would that be allowed in the regs?

Would this then likely pass an PIR inspection in the future?

or is this just a no no.

I have actually 3 timed overrun fans to wire ( what the inspector wanted ). If the method i just described is acceptable could i use this method for the other 2 fans just changing the pull cord switch for a standard light switch.

Sorry to carry on, want this work to be able to pass a PIR inspection test in future so need to get it right.

Many thanks

 

[ban-all-sheds]

How about his:

T/E from SFCU to a lighting JB, or a 4-strip of choc-block in a choc-box.

T/E from JB to one side of the DP switch, i.e. permanent live on red/brown, switched live on black/blue, sleeved red/brown, brought back to the 4th terminal of the JB.

3C/E from the JB to the fan.

 

[timmyquick]

How about his:

T/E from SFCU to a lighting JB, or a 4-strip of choc-block in a choc-box.

T/E from JB to one side of the DP switch, i.e. permanent live on red/brown, switched live on black/blue, sleeved red/brown, brought back to the 4th terminal of the JB.

3C/E from the JB to the fan.

That actually seems a very good solution, but as the ceilings will have no access ( they will be sealed with plaster board with no loft access only to the bathroom ) i can not use a junction box ( from my understanding JB need access) but if i use an 8 strip of choc-block 4 connections for existing light circuits and make just a big enough hole for the choc-box to go through the plaster board and cover with a very big flat round light fittings which i already have, do you think this would be compliant with REGS? and pas a PIR inspection in the future? as i really like this solution simple clean and will work a treat. I have 3 fans to install in total one for the bathroom where the single brick building has been made into cavity wall, this is why its under building control. 1 fan in the kitchen 6 inch which has had a new wall built as well ( the bathroom is above ). And a fan in the old coal house which has been rebuilt as extension to kitchen. For some silly reason inspector wants timed overrun on all fans.

Is it also ok to feed fan in kitchen and extension from lighting circuit? as they are easier to feed from as all the lighting circuits are in place from the original structures and is inconvenient to tap into something else. obviously i would use a standard lighting switch in the Kitchen and extension.

Brilliant solution ban-all-sheds been on this forum for hours trying to figure out the best way to do this.

 

[timmyquick]

Just thought for kitchen and extension i could use a sunken box in wall use 4 chock-blocks and a blanking plate on top next to switch. That will be the required access and I believe this practice is still compliant? any yes or no answers from you experts will be good.

I am most likely going to go for ban-all-sheds solution unless anyone sees a problem with that?

Thanks for everyone's help so far

 

[ban-all-sheds]

Just thought for kitchen and extension i could use a sunken box in wall use 4 chock-blocks and a blanking plate on top next to switch

Just use a 45mm deep box for the switches- there'll be room for the connector blocks inside them - no need for separate ones. Or use dual-accessory boxes, put the FCU and the switch next to each other, and wire them together directly - no need for connector blocks.

As for the JB inside a ceiling, yes, it will be inaccessible. Chances of a Periodic Inspection finding this? About zero.

Yet again I wonder why you can't buy square pull switches, except for stonking great shower ones. If you could, you could surface or flush-mount the FCU and the pullswitch in a dual accessory box, and just wire straight from one accessory to the other there as well...

 

[timmyquick]

Can you run cable horizontally straight trough the duel accessary box? or do you have to go up vertically then down again never seen a dual accessary box in use before.

is this what you mean?

Take supply from lighting circuit into SFCU inside duel accessary box. wire T/E like this - Red wire into live on SFCU, Black wire sleeved red into a chock block. Then the other end of this T/E taken into a standard light switch black being sleeved red. Take 3C/E from time overun fan into the SFCU wiring like so. Red permanent live into live on SFCU, Blue sleeved black into neutral on SFCU and then yellow ( switched live) sleeved Red taken into the chock block which has the switched live from standard light switch.

Thus giving fused 3 amp circuit for fan and only using one duel accessory box as the light in kitchen and extension can then be on a 2 gang 1 way switch inside the dual accessory box.

If there is something wrong with this or i have misunderstood please let me know as soon as possible as i am doing this saturday midday.

And thanks for all the help.

This is actually my brothers house and i lent him some money untill he gets retention back on mortgage and he wont untill these fans are in so its in my interest to get this done, but also done right as he will eventually be having a PIR inspection as all home owners will have to do so.

 

[ban-all-sheds]

Can you run cable horizontally straight trough the duel accessary box? or do you have to go up vertically then down again never seen a dual accessary box in use before.

They vary - some you can go across inside, some you'd have to come out and in again.

is this what you mean?

No. T/E feed (Live & Neutral) to supply side of FCU.

To the load side connect a single red from L to the COM of the light switch.

Connect your 3C/E as follows.

RED to Load L of FCU
Yellow, sleeved red, to L1 of light switch
Blue (sleeved if you want, but no need) to Load N of FCU.

No need for choc-blocks....

If there is something wrong with this or i have misunderstood please let me know as soon as possible as i am doing this saturday midday

Hope it went OK..

he will eventually be having a PIR inspection as all home owners will have to do so.

And when do you reckon that will be the norm?

 

[andy]

when we re-wire houses, they are fed from the lightin circuit to an isolator outside the bathroom then the fan. there are no fuses connected

 

[andy]

RED to Load L of FCU
Yellow, sleeved red, to L1 of light switch
Blue (sleeved if you want, but no need) to Load N of FCU.

i have to disagree with you on that. your mixing two versions of colours in one cable. either sleeve the red and yellow brown and leave blue, or sleeve yellow red and blue black leaving red

 

[ban-all-sheds]

when we re-wire houses, they are fed from the lightin circuit to an isolator outside the bathroom then the fan. there are no fuses connected

Then you are probably contravening the manufacturers installation instructions.

If you are doing that for money, you are guilty of fraud....

 

[andy]

we dont put new fans in: we simply re-conect the existing fans (which we wired the same way)

 

[ban-all-sheds]

RED to Load L of FCU
Yellow, sleeved red, to L1 of light switch
Blue (sleeved if you want, but no need) to Load N of FCU.

i have to disagree with you on that. your mixing two versions of colours in one cable. either sleeve the red and yellow brown and leave blue, or sleeve yellow red and blue black leaving red

No - Red/Black and Red/Blue/Yellow are the pre-harmonisation colours. Lives which are not red should therefore be sleeved RED, not brown.

AFAIK, there has never been a requirement to sleeve neutrals on single phase circuits.