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#110502 - 04/28/06 08:21 AM Bath Fan Mess - UK  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,260
Fullerton, CA USA
from Chipmunk

Quote
I found these while researching a non-functioning bathroom exhaust fan
in my partner's flat (apartment) here in the UK.

This fan was within the shower enclosure, 1 foot (30cm) above the
shower head, certainly within the spray zone.

The initial symptom was that the fan would run only intermittently,
and not at all on it's automatic (humidity controlled) setting.

The fan was connected between blue and yellow, with the red capped.
From the fan isolator switch location, I could tell the red is
supposed to be permanently live, blue neutral, and yellow switched
(with the bathroom light). However in this isolator switch box, the
yellow was capped off!

All became clear once I had removed the fan. The fixing screw had
penetrated the cable on its way into the red plastic wallplug, and
shorted red and yellow. It had stopped working because the damp had
finally rusted away enough of the galvanized screw to break the
connection. (Apart from the fizzing and arcing).

This was obviously faulty from install, yet the installer covered it
up (or didn't realize it was a fault, not sure which is scarier).

What terrifies me is that this fixing screw was in a brick wall less
than 1 foot (30cm) from the fixing for the metal shower enclosure.
Anyone want to risk the damp plaster not being conductive enough to
cause dangerous leakage to the unearthed enclosure frame?


[Linked Image]


[Linked Image]


Happy ending however, I was able to pull out enough slack on the cable
to get a new termination neatly (While avoiding the cable with the
screw).


2017 / 2014 NEC & Related Books and Study Guides

#110503 - 04/29/06 06:46 AM Re: Bath Fan Mess - UK  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Quote
This was obviously faulty from install, yet the installer covered it up (or didn't realize it was a fault, not sure which is scarier).


Definitely scary!

With the usual connections as you describe -- red permanent live, yellow switched live, blue neutral (was it sleeved black by the way? [Linked Image] ) -- the screw shorting red and yellow would result in the bathroom light being on all the time.

So I'm assuming that the red was disconnected and capped at the isolator switch, so that than fan then received all its power via the yellow (when the light was on ) and the screw?


#110504 - 05/01/06 06:15 PM Re: Bath Fan Mess - UK  
chipmunk  Offline
Member
Joined: Jul 2004
Posts: 144
Southampton, UK
No Paul, it wasn't sleeved black :-), and it was the yellow that was isolated at the supply end, with red isolated at the load end. In other words the fan was hooked up to run with the light on, but actually ran all the time. (Having a humidistat, this wasn't a bad thing, but for the *way* it was getting the power).

[This message has been edited by chipmunk (edited 05-01-2006).]


#110505 - 05/02/06 07:39 AM Re: Bath Fan Mess - UK  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Quote
it was the yellow that was isolated at the supply end, with red isolated at the load end


Ah, I'm with you now. So the guy left it knowing full well that the 240V he was applying to the red wire at the switch was appearing on the yellow at the other end despite the fact that it shouldn't be?

What was he thinking??!! [Linked Image]


#110506 - 05/02/06 08:31 AM Re: Bath Fan Mess - UK  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
For the benefit of those not familiar with U.K. wiring, here's a rough (very!) sketch of a typical fan installation of this type.

Note black wire on switch loop sleeved red to re-identify as hot, and blue on the 3-core sleeved black at ends to re-identify as a neutral/grounded conductor. Earths/EGC omitted for clarity.

[Linked Image]


#110507 - 05/03/06 06:11 AM Re: Bath Fan Mess - UK  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,217
SI,New Zealand
Good easy to understand diagram there Paul. [Linked Image]
What on earth possessed someone to do a job this rough, in a shower enclosure of all places??.
It's a wonder no-one got electrocuted. [Linked Image]


Let's face it, these days if you're not young, you're old - Red Green grin


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