What Do You Notice About The Way It Is Wired?

[securespark]

It's a Denman's timer fan built in 1999.
The timer module failed so I took a similar fan from the ensuite where the fan had packed in and made one good one out of the two.

Ignore the two blue wires joined with a block, that was a redundant pull switch.
I did this work 2 years ago and recently took the fan down as we are decorating and I cleaned it.

 

[Lectrician]

No idea what I’m looking for, other than no obvious supply cable…

 

[RandomGrinch]

Has it been running for 2 years now?

 

[SFK]

The motor winding is permanatly live?
(white wire from chockblock L going directly into the motor windings).

 

[SFK]

And looking at it again - does the neutral also go straight to the motor?
So this means that the mains are directly driving the motor and the electronics are doing nothing?

 

[sparkwright]

There's the blue wires in the connector block that was a pull switch, which you categorically asked us to ignore - some form of reversed polarity?

 

[JohnW2]

And looking at it again - does the neutral also go straight to the motor? ... So the mains directly driving the motor and the electronics are doing nothing?

That's what it looks like.

However, I think we must be missing something ('obscured'?) - since there does not seem to be any visible 'output' from the timer module (just an L, N and 'trigger' input).

Kind Regards, John

 

[SUNRAY]

This is what I think I see:

 

[JohnW2]

This is what I think I see:...

That would make sense, were it not for the fact that we had been explicitly told to 'ignore' the blues going to the connector block! Maybe secure didn't mean 'totally ignore'?

Kind Regards, John

 

[SUNRAY]

That would make sense, were it not for the fact that we had been explicitly told to 'ignore' the blues going to the connector block! Maybe secure didn't mean 'totally ignore'?

Kind Regards, John

I'm assuming the original unit had the switch to stop the fan completely and the instruction to ignore it was to treat it as a single continuous wire.

 

[securespark]

Sorry, I meant to say ignore the fact that I botched them together with a terminal block.

The fan does indeed work.

Has it been running for 2 years now?

That particular fan winding has been running every single day since July 1999. The timer module is snaffled from the other Denmans timer fan in the house. Both were fitted at the same time.

The white wire does indeed connect the permanent live to one side of the fan.

One of the blue wires connected to the single block comes off the PCB, the other goes to the other side of the fan.

The neutral from the supply block also connects to the PCB.

Sounds a bit of a let-down now, but I don't know how I have managed to go all this time without realising (and never thought about), that the PL goes direct to the fan and the neutral via the module.

Sorry, fellas, I think I misled you into thinking this was some great revelation.

 

[SUNRAY]

Sorry, I meant to say ignore the fact that I botched them together with a terminal block.

The fan does indeed work.

That particular fan winding has been running every single day since July 1999. The timer module is snaffled from the other Denmans timer fan in the house. Both were fitted at the same time.

The white wire does indeed connect the permanent live to one side of the fan.

One of the blue wires connected to the single block comes off the PCB, the other goes to the other side of the fan.

The neutral from the supply block also connects to the PCB.

Sounds a bit of a let-down now, but I don't know how I have managed to go all this time without realising (and never thought about), that the PL goes direct to the fan and the neutral via the module.

Sorry, fellas, I think I misled you into thinking this was some great revelation.

Oh well you don't know yet, there is always the chance someone may come along and tell us we are wrong.

 

[securespark]

An unexpected update....

I cleaned and reassembled the fan and refitted it.

Reconnected the 3 core feed.

Yellow (SL) to T
Red (L) to L
Blue (N) to N

Turned on TP iso: fan works.

Turned off pullcord for light: light stays on.

Discovered that with pullcord in one position, the light goes out when the TP iso is switched off.

Did further tests with various conductors disconnected from the fan.

Soon discovered the fan was not the issue.

In all cases, L-N was 231V and SL-N was 231V and SL-L was 0V with the light pullcord in either position.

Nothing has changed: light switch, light fitting, isolator and fan are all the same, so there must be a short somewhere...

Is there a fault through the PCB? No, as the fault exists when the PCB is disconnected from the supply.

Final test: Voltage check between screw in wall and N - 184V.