Fusing bathroom timer fans

[goasis]

Hi all, happy Christmas! There was a thread on this subject a while back, not many people said that they actually connect bathroom extractor via a 3A fuse, despite many MI's seemingly asking for it. And certainly it's not something you see often, triple pole isolators yes, sfs's less so. Is it something we mostly just 'overlook'.
And if you were to do it, would you loop power in/out throught a sfs, then drop down to light switch off load side. All bath lights and fan off load side? Do away with TP iso?

 

[telectrix]

just find the round brown lighting JB in the attic with L,N and S/L inside and the cpc.s twisted over the box. 3 croc clips and away you go.

 

[brianmoooore]

No isolator other than the s/fused spur is required if it is located adjacent too the fan or immediately outside of the bathroom door.
A job I did in my own house yesterday was to change the wall mounted bathroom fan (building works have made it no longer on an outside wall) for an inline fan in the loft. Original (sole) isolator is a s/fused spur immediately outside the bathroom, but now I have added a TP isolator next to the fan in the loft. Also serves as a junction between the fan's flex and the fixed 3&E.
I think I've posted on here before about a fire in a new build near me which the rumours said was caused by the omission of the 3A fusing required by the instructions.

 

[radiohead]

I think I've posted on here before about a fire in a new build near me which the rumours said was caused by the omission of the 3A fusing required by the instructions.

It wasn't caused by the omission of a 3a fuse, because a current far exceeding 3a could flow for a long time on a seized fan motor, sufficient time to cause the motor to seriously overheat before the 3a fuse blew.
I recall the case and the manufacturer of the fan used the omission of the 3a fuse by the contractor as a get out of liability, despite the fact that a 3a fuse almost certainly would not have changed anything.
One problem with fusing fans is in replacement of existing fans where a fuse has not been installed. Rearranging the wiring to fuse the whole bathroom via an FCU is overkill where an existing fan has failed, I normally replace the standard 3 pole switch, if fitted, with a clik 3 pole/fuse combination which fits a single plate, and just fuse the perm live. The fan runs on the perm live, NOT the sw live, so IMO that is sufficient to meet manufacturers requirements. Alternatively use a fan which does not require fusing, Vent Axia is one example.
Of course on new work it is a simple matter to arrange for all line conductors to be fused with an FCU feed to the bathroom.

 

[brianmoooore]

It wasn't caused by the omission of a 3a fuse, because a current far exceeding 3a could flow for a long time on a seized fan motor, sufficient time to cause the motor to seriously overheat before the 3a fuse blew.
I recall the case and the manufacturer of the fan used the omission of the 3a fuse by the contractor as a get out of liability, despite the fact that a 3a fuse almost certainly would not have changed anything.

Very possibly, but having successfully absolved themselves from liability, no doubt the contractor got the blame, which he could have avoided if he had fitted the fan to the manufacturer's instructions.
The switched live usually connects straight to a fairly high value resistor in these fans, so there's arguably no possibility of overload on this supply, and S/C protection would be taken care of by the 6A MCB in the CU.