General > General Technical Chat
UK toilet extractor fan
Majorbob:
--- Quote from: themadhippy on August 17, 2021, 10:03:29 pm ---The fan has a timer built in so will have a permanent live,switch live and a neutral,and will require a 3 pole switch to safely isolate all current carrying conductors .
--- End quote ---
For now, it will just get whatever switch faceplate I have available. When I get round to it I'll upgrade it to a 3 pole. (Probably when it either goes wrong or I sell the house if its anything like the "temporary" measures I usually come across)
For those who are so inclined, they may refer to the room as "guest facilities".
themadhippy:
in that case i'd wire the permanent live to the live side of the spur and the switched live to the neutral side ,that way you are able to switch off both lives.
Zero999:
--- Quote from: Gyro on August 17, 2021, 10:01:00 pm ---
--- Quote from: Zero999 on August 17, 2021, 09:42:45 pm ---Regarding the original post: just use a 3A fused spur, which gives you the advantage of being about to isolate the fan, so it can be serviced, whilst keeping the lights on.
--- End quote ---
An FCU (fused connection unit) is a fused spur - normally the one with a flex outlet.
To be completely accurate, the fan can only be serviced whilst the lights are on apart from the toilet / lavatory / shithouse one. The fan has a permanent live (via the fuse) and a switched live (from the switch or light fitting). Hence the use of multi-pole fan isolators.
--- End quote ---
That's true. It does seem odd that the fan requires a 3A fuse, yet the timer is designed to connected to a standard 6A lighting circuit. If you're really paranoid, you could put the light on a 3A spur.
Monkeh:
--- Quote from: Zero999 on August 19, 2021, 06:18:15 pm ---
--- Quote from: Gyro on August 17, 2021, 10:01:00 pm ---
--- Quote from: Zero999 on August 17, 2021, 09:42:45 pm ---Regarding the original post: just use a 3A fused spur, which gives you the advantage of being about to isolate the fan, so it can be serviced, whilst keeping the lights on.
--- End quote ---
An FCU (fused connection unit) is a fused spur - normally the one with a flex outlet.
To be completely accurate, the fan can only be serviced whilst the lights are on apart from the toilet / lavatory / shithouse one. The fan has a permanent live (via the fuse) and a switched live (from the switch or light fitting). Hence the use of multi-pole fan isolators.
--- End quote ---
That's true. It does seem odd that the fan requires a 3A fuse, yet the timer is designed to connected to a standard 6A lighting circuit. If you're really paranoid, you could put the light on a 3A spur.
--- End quote ---
It likely calls for the fuse in both permanent and switched lines. The manufacturers need to learn to protect their own damn equipment.
Gyro:
--- Quote from: Zero999 on August 19, 2021, 06:18:15 pm ---That's true. It does seem odd that the fan requires a 3A fuse, yet the timer is designed to connected to a standard 6A lighting circuit. If you're really paranoid, you could put the light on a 3A spur.
--- End quote ---
They're normally combined units these days (ie. timed [Edit: run-on] fans), with the fuse protecting both the fan motor and the timer circuit. 3A does seem high considering the contents - normally a resistor dropper, shunt zener regulation, CD4xxx IC and a TO92 Triac a few passives and a preset pot, but 3A is the lowest commonly available value so I guess that's the reason.
Most (I can't say all) fans just call for a fuse on the permanent line - otherwise you would be fusing the light fitting too (not that it would be a bad thing though).
I recently had to repair one of our fans, the under-rated electrolytic across 15V CD40xx logic supply had gone short (not leaked). The mains dropper resistor was still merrily dropping mains with a few % additional dissipation. After a decade or so of use, the phenolic PCB and plastic casing around and above it was a little browned, but no fuse on earth would really stop it melting down if it wanted to. The switched line isn't much of a risk because it goes straight to a decent body size high value series resistor to be clamped and rectified as a logic input.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version