Time clock stopped working

[uksparks]

Hi,

any ideas chaps? Got the time clock below, was working fine 12 months ago before works started, just gone to power up and am getting no voltage on the output, wound it up etc...

 

[davesparks]

Yeah the timeswitch will be able to switch high load, on a SP supply the tails would go straight through it without a contactor.

Is 32A enough for that many storage heaters? But I guess with that many they may not all be the usual 3.5KW jobbies?

 

[davesparks]

As mentioned earlier, a little box I had to put together recently to replace a defunct working light control in a theatre.




Reading from the right we have
-Main switch
-Outgoing cct MCBs
-Contactor
-1A MCB for control cct
-Impulse relay
-24V Impulse timer (for switch debouncing)
-24V PSU

24V cct works like this:
pushbuttons are N/O and trigger the impulse timer, the impulse timer switches its contacts for the specified time then resets.

240V control cct:
The timer switches a 240V supply to the coil of the impulse relay, the relay switches 240V to the contactor coil.

All of the control ccts are fed via the 1A MCB, including a 240V remote override (the red one coming out of the 1A MCB)


And yes there are a few things there which you could call in to question, feel free to question me on them and I will endeavour to explain when I get back from work later, hopefully be home by 3AM.

 

[uksparks]

Thanks or this Dave, looks good, and I do appreciate your comments, I don't have a great deal of experience in this side of things, nothing to hide, I'll be quite honest but we all have to learn / start somewhere.

I think I'll squeeze a mcb in next to the Contactor.

Well it's 32A per phase and there's only 4 heaters per phase max, the heaters only draw approx 1.5kW each some are more, but I did balance it so that each phase draw was under 32A.

I suppose my only concern would be any earth leakage, the accumulation of 12 heaters, hopefully it won't be so much it trips the RCD, otherwise I'll be having to rethink things and incur a fair bit of cost.

 

[davesparks]

Go on, play spot the deliberate mistake with those pics!

Well you see I am far more used to the big jobbies at 3.5KW and 16 sodding bricks each to carry up flights of stairs. But then they were usually 1 or 2 in the whole property which were expected ted to heat the whole house. One in the hallway, one in the living room and maybe one upstairs, plus the bottom immersion makes a 4way board nicely.

Assuming the heaters are new there shouldn't be any earth leakage on them. Old ones may have a bit of leakage but that's likely to be the elements which are easily replaced and pretty cheap.
Personally I'd have found a way to not need an RCD for them, steel conduit in the chases would probably be my first choice. But then that is my first choice of wiring system on any surface work anyway. Ran a bond to a gas pipe in it the other day just to prove to a plumber that it is possible to get three 90degree bends into a pipe accurately without having to cut and join the pipe.

Did you consider the normal installation in your balancing calculations? Doubt it will have much effect during the off peak hours but if it has afternoon boost it may skew your balance a bit
But don't worry about that, in the grand scheme of things it won't cause anyone any problems.