Extractor Fan Rules & Regs

[bert]

The landing at the top of the start is enclosed and gets very warm this weather so I want to install an extractor fan in the loft above. NO bathromm/shower/toilet, no water involved at all.

So do I "need" all this performance with triple gang switches etc or can I simply wire it through an on/off switch.

I could take power from the upstairs lighting circuit quite easily or alternatively there is a redundant immersion heater supply I could use.

I'm thinking of using a 100mm Manrose MF100. Any comments or alternative suggestions welcome

[Tim Watts]

2 pole isolator - ie the "normal" type.

The only reason the 3 pole fan isolators are used is to isolate the trigger from a lighting circuit as well as the permanent live and neutral feeds. If you don't have that trigger line, you don't need a 3 pole isolator.

As for the type, the Soler & Palau are not bad fans - I have an axial (in duct) one.

[ARW]

Is there a reg that requires you to switch the neutral?

[Tim Watts]

I have no idea on which, if any reg???

But I would assume, if the isolation is designed for maintenance purposes, then all current carrying conductors must be isolated (neutral being regarded as "live" rather than "Live").

But to throw it back - why are fan isolators 3 pole and all (AFAIK) switch-isolators (20A and upwards) all double pole?

[Dave Liquorice]

I thought "isolation" rather than simple "switching" required double pole and >3 mm gap.

[tabbypurr]

A regular switch works fine. The deal with lighting fed fans is they have 3 feed lines.

4" fans are a total waste of time if you want to ventilate anything bigger than a cupboard. No way will they keep up with the heat load of a loft. You need to be looking at at least a 12"er, and it'll need to run for hours to really be effective.

Fans are prone to catch fire at EOL, and of course problems aren't detected if in a loft. Take precautions re this.

NT

[ARW]

Yes, but John Holmes is dead.

[ARW]

Not for a TN system.

Because of all the bollocks that people make up to justify their job where they do f*ck all for a living.

Architects as the no 1 wankers for interfering in other peoples business without a clue about what they are talking about.

[Charles Hope]

The architects I know don't demean themselves with electrical details. They leave that to the "M&E consultant" (mechanical & electrical). That often means either the plumber or electrician involved.

[ARW]

Then why do they put the electrical details on their plans?

[Graham.]

And why do triple-pole fan isolators have such wide dollies**? Is a convention that just happened, rather than any regulatory requirement?

** A little arcane, but I couldn't think of a better word. My late farther-in-law, who was an electrician, always used dolly whatever the actual shape. Toggle perhaps?

[Tim Watts]

But John Noakes is alive :)

[ARW]

Probably the most cutting edge joke ever.

:=)

[Tim Watts]

Makes sense...

Or possibly, it's easier if everyone switches out all current carrying conductors rather than worrying about if it is a TT or not system? I suspect in this case, it's cheaper and easier if everyone just specs DP/TP isolators rather than justifying

Talking of bollocks - have you started fitting all metal CUs?

[Adam Funk]

I've always assumed it's to make them easier to flip because they're usually (in bathrooms) out of easy reach!

[Adam Funk]

Well, I'd hate to have an argument with you, but why would the companies that build new houses put 3-way isolators in if they didn't have to? They seem to try to do everything in the cheapest way that meets the regulations (e.g., not enough sockets). (Same with isolator switches above worktops for the sockets behind the under-counter appliances --- why would they spend an extra £5 if they didn't have to?)

[Bill]

In message , ARW writes

Too right. I had an argument with one who insisted that I put an aerial inside a reinforced concrete room on top of a building because it wouldn't look nice on the outside. The fact that it would be totally inefficient and not work correctly was something that he just couldn't understand.

[bert]

I'm not trying to cool the loft.

So all the in line extractor fans mounted in the loft above shower cubicles are a major fire hazard? They do have thermal cut outs.

[tabbypurr]

rocker

NT

[tabbypurr]

are they?

precaution satisfied