Contactor advice

soulman · Sep 27, 2014

Hi all,

First of all i haven't much experience with contactors, I need to install a timer to switch 3 discharge lamps. I vaguely remember from my training that contactors should be used when using a timer unit to switch discharge lighting, as timer contacts will burn out when switching the load off.

My question is can i use the same circuit to switch the coil. L & N to timer input & top of contactor, link N to bottom of coil & SL to top of coil.

Thanks

Andy78 · Sep 27, 2014

What's the total load of the discharge lamps ?

Richard Burns · Sep 27, 2014

Salient question from Andy78; also the timer might not like the current surges of discharge lamps, but it would be a limited separation even if on another MCB.

[ElectriciansForums.net] Contactor advice

Andy78 · Sep 27, 2014

I knew you would be the guy with the diagrams Richard :smilewinkgrin:

@OP I know you can get timeclocks to handle small discharge loads, but the deciding factor might be cost. It may be cheaper to use a non discharge suitable timeclock and a contactor as per Richard's diagram.

soulman · Sep 27, 2014

Total load 450w

Cheers

Richard Burns · Sep 27, 2014

450W is a fairly low load but discharge lighting would probably push the limits of a basic timer wired directly because of the peak currents.
You could probably use the same circuit for that sort of load.

soulman · Sep 27, 2014

Hi Richard on most of the timers i have looked at they are 8A resistive 8A inductive but all say no switching of discharge lighting or max 70w

Cheers

Richard Burns · Sep 27, 2014

soulman said:
Hi Richard on most of the timers i have looked at they are 8A resistive 8A inductive but all say no switching of discharge lighting or max 70w

Cheers

Sorry, I was not quite clear on that, I would use the contactor but I would expect that you could use a single 6A, maybe 10A MCB, maybe type C (depending on the number of fittings) to protect both the timer/contactor coil and the load. If you have to option to split the timer and contactor then why not, easier for fault finding.