fusing down when using 3 core and earth

[2330john]

Hi all first post

Can't figure this out

How do you put an FCU on a fan as many makers suggest

If you take your feed and switch live from the lighting circuit (ceiling rose) in 3 core and earth, that goes through an isolator to the fan, how do you fuse it down.

thanks

 

[paul b b]

fuse it down to what?

 

[Barx]

When on the lighting circuit if it's a fan that requires perm and switched live then it's just a triple pole isolator for isolation. If it just needs perm then switched fuse spur.

This is how it is normally done though I have had councils that insist it is fused to and the only way we could agree to do this was to run both the bathroom light and fan from the spur. So if spur was off bathroom light no worky worky. Thus switched live is also dead.

 

[2330john]

Fan makers say the fan should be fused at three amps, so that means a FCU, how do you do that when switching the fan on with a switch live and have a perm live for over run.

 

[Lee321]

fcu the light

 

[ProDave]

I ignore the stupid fan makers instructions if it's fed from a 6A lighting circuit.

 

[Lee321]

I ignore the stupid fan makers instructions if it's fed from a 6A lighting circuit.

i'd second that. its rarely done

 

[ianmacd]

Well you could fit a 3A FCU inline with the perm line as the switched line should only be used as a reference rather than used to draw any current but I think I would tend to agree with Dave and Lost on this one.

Was reading the manufactures instructions on a UFH mat yesterday that said it should be protected in a special location by a 5mA RCD .

 

[Apache]

Someone needs to make a 3 pole fan isolator that will take a 3A fuse!

 

[sparkytim]

How it always used to be done is to put 3 amp FCU on supply to bathroom light then 3 core from light to fan, so fuse protected light and fan, only problem is if you turn Off FCU then light goes out as well, so 3 pole switch came in to enable fan only to be isolated.

 

[ianmacd]

Someone needs to make a 3 pole fan isolator that will take a 3A fuse!

Or 2 (one for each line connector).

 

[wozz]

i always fuse down the supply to the bathroom if it has a fan. i cant see the problem with isolating the fan and the light. and removes the need for a fan isolator which are not pleasant to look at.

 

[ianmacd]

i always fuse down the supply to the bathroom if it has a fan. i cant see the problem with isolating the fan and the light. and removes the need for a fan isolator which are not pleasant to look at.

So you replace it with an equally ugly SFCU? Also in a windowless bathroom, how can you see anything to change the fan the isolator is there for?

 

[Evans Electric]

If installing a timed fan we always fit a spur unit in the feed to the bathroom light because light and fan are now linked by the trigger wire . Omit the 3 pole switch. Spur can be an RCD one if required . Spur fitted outside the room or above the door .

Deke

 

[JUD]

So you replace it with an equally ugly SFCU? Also in a windowless bathroom, how can you see anything to change the fan the isolator is there for?

Agreed. The isolator is there so you can isolate the fan for maintenance etc. without taking out the light.

Lights can come in handy when it's dark :^O :^O :^O

 

[batty]

The way I see it if the fan is blowing a fuse it probably is nackered and wants replacing so I only ever fit 3 pole fan switches this also gives customer option of switching fan off if they don't want it running for 15 minutes in the middle of the night.

 

[wozz]

So you replace it with an equally ugly SFCU? Also in a windowless bathroom, how can you see anything to change the fan the isolator is there for?

in my defense swt fu spurs are alot more common than fan isolators so i would consider a well placed swt fu spur more acceptable than a fan isolator to the customer.

And i believe if some one is competent to lock off a supply to a fan and work on the fan they should be able to get around the fact there is no light in the room.

sorry for the spelling / grammar i have been drinking.

 

[Adrian]

fit a fcu on bathroom light supply then fit a 3 pole isolator next to it above bathroom door. job done

 

[Megaohm7]

I wouldn't worry about it mate .. I have never had any problems with fans that are wired into the lighting circuit as that is generally the norm . but You have done the right thing in asking as You will never stop learning in this industry Guinness

 

[Risteard]

Clearly the 3A fuse for fans is a nonsense, however the Regulations require adherence to manufacturers' instructions. Therefore to certify that an installation complies with BS7671 then the fan must be fused down if required by the manufacturer.