2 wire lighting PIR, inline timer fan problem.

[RedSnedd1903]

Morning all. I have a problem on a Job were working on at the moment. I have a small toilet area fitted with a number of LED lights and an in line timer fan. They are both controlled from a 2 wire ceiling PIR. The problem is once the lights switch on initially the fan comes on also but once the lights switch off in the toilet ,the fan stays on forever. Even though the timers down to 1 minute. Checked the connections at the fan and they are correct although when the lights switch off I am still getting 50V on the switch wire. I am assuming this voltage is what is keeping the van running.

Thoughts anyone.

 

[HandySparks]

Might be worth temporarily adding an ordinary filament lamp into the circuit (or swapping one of the LED lamps for halogen) as a diagnostic measure.

 

[RedSnedd1903]

Unfortunately the led lights are all sealed units. The fan is in an adjacent attic space as there is no access above the toilet area. The guy who fitted the PIR and lights threw out the instructions but mentioned that they had said something about a capacitor being fitted to the unit for circuits with a low load.

 

[RedSnedd1903]

How would a capacitor fit into the circuit?

 

[HappyHippyDad]

This will NOT be my strong point, but could this not just be a faulty timer function on the fan?

The effect that capacitance has on LED lights can sometimes lead them to stay on very dimly when switched off, but I cant see this keeping a 230V fan going? Also I cant see 50V keeping the fan going?

Could be very wrong though and looking forward to the other replies.....

 

[trev]

What make are these lights? The installers instructions are bound to be on line, jfgi mate

 

[HandySparks]

Unfortunately the led lights are all sealed units. The fan is in an adjacent attic space as there is no access above the toilet area. The guy who fitted the PIR and lights threw out the instructions but mentioned that they had said something about a capacitor being fitted to the unit for circuits with a low load.

OK, so just as temporary diagnostic measure, lash a 25W (or smaller) GLS lamp in a batten lampholder in the attic space, wired across the switched live and neutral of the fan and see what happens.

This will NOT be my strong point, but could this not just be a faulty timer function on the fan?

The effect that capacitance has on LED lights can sometimes lead them to stay on very dimly when switched off, but I cant see this keeping a 230V fan going? Also I cant see 50V keeping the fan going?

Could be very wrong though and looking forward to the other replies.....

This is a timer fan, so the switched live will just be providing the trigger for the fan timer and will need very little current. The main power for the fan will be via the permanent live.

 

[guest119]

Which way is the 50v coming?
Disconnect the switchwire at the fan and see.
Are any of the leds emergency units?

Boydy

 

[davesparks]

My vote would be that it's coming from the PIR,

 

[HandySparks]

My vote would be that it's coming from the PIR,

Actually, re-reading the OP, I suspect that you're right. The 2 wire PIR might well be deliberately 'leaky' in order to work. Might be best to change the PIR to one requiring a neutral and with a relay output, if that's possible.

 

[davesparks]

My thoughts exactly, it's going to be using the load as it's connection to the neutral when it's switched off.

The same way the pilot neon on external switches can do this.

 

[RedSnedd1903]

Cheers for the replies guys. I ended up replacing the PIR with a new one( neutral connection ) and it done the trick. Davesparks and handyspark I think you hit the nail on the head there. Thanks for the replies guys. Think I understand how it works better now.