DIY Doctor

replacing ensuite extractor fan but no earth connection

Postby trebor-trix » Sat Jan 20, 2018 1:20 pm

so my shower extractor fan failed recently, though the light still worked, the fan started but didn't run for very long, i chose to replace just the fan, bought a Manrose MF100S from Screwfix, removed the old fan, only difference was the new fan had no 'earth' connection.
sought some advice, and tucked the earth wire out of the way and insulated.
But on wiring up the new fan, using just N & L wires, the fan runs, despite the switch still being off..
checked the wiring in the junction box that feeds the light & fan, nothing seems amiss.
the new fan has a movable blade fuse connecter for determining how long the fan runs for, 3 mins - 25 mins, tried different slots, it still runs, even, when switched off though..
any thoughts..
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sat Jan 20, 2018 1:02 pm


Simply Build It

Postby trebor-trix » Sat Jan 20, 2018 3:10 pm

now resolved, my 'go to electrical help neighbour' returned home, the 'earth' wasn't an earth..
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sat Jan 20, 2018 1:02 pm

Postby Mr White » Sat Jan 20, 2018 4:43 pm

A fan with a timer uses 3 wires, Live, Neutral and switched Live

Are you sure it was the earth you did not connect?

It may also be that who ever installed it did not know and used a twin and earth and the earth cable as a switched live. If they have you should change the cable to a 3 core and earth and do the job properly.
Mr White
Rank: Site Agent
Progress to next rank:
Posts: 875
Joined: Tue Jun 20, 2017 9:54 pm

Postby Sam_diy87 » Mon Mar 01, 2021 9:57 pm

Evening, having the exact same issue with the same fan. Can I check, is the yellow (3rd) wire the neutral and does the switched live and perm live go in the same slot? Thanks
Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Mon Mar 01, 2021 9:53 pm

Postby ericmark » Tue Mar 02, 2021 11:28 am

One you should start a new thread, as answers to you may not be the same as answers to original poster and it could generate emails to original poster.

As to colours red, yellow, blue, or today brown, black, grey are the colours used for three phase machines, and have no meaning with a single phase supply, in theory we should see red or brown sleeves, and black or blue sleeves but this rarely is the case, so you have to look at the original terminals to see what colour does what, or find other end of cable, often in the ceiling rose.
Rank: Project Manager
Posts: 2536
Joined: Fri Oct 02, 2009 8:49 pm
Location: Llanfair Caereinion, Mid Wales.

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics