fault

[1983]

good eveing every1 i was at a job the other day with a mate helping out on sum cctvs in a wearhouse.
i was asked 2 look at one of them flood lights on the wall as it was hanging the onwer said that since it has been hanging everytime he trys 2 switch them on it trips.

1st i isloted that light and flicked the msb 2 c if it will trip and it still did haveing a look at the d/b there is a fuse for the flood lights but i noticed it was wired to a timer it also has an relay wired nxt 2 it.

there is one mcb for the fllod lights and one for the timer. when the mcb for the lights are on the lights dnt work when both the mcb for the timer and lights are on it trips the msb for the lights.

any ideas where the fault may be? im feeling a short circuit sumwhere between the timer and relay all help much appreicated thanks in advance and sorry bout the long discreption

 

[Hawk81]

i think that you need to disconnect the load from the relay. that way you can narrow the fault down easier to either the lights or timer/relay.

 

[1983]

thanks mate ill give that i try

 

[Des 56]

The dualling of the mcbs will be so that the timer carries only the switching current of a contactor
The contactor on its own mcb supplies the lights via the load side of that contactor

So if you switch on the timer mcb on its own it likely will stay on because it doesn't feed the lights

When the mcb for the lights is switched on by itself,it likely will carry no load so wont trip
When the timer mcb is then switched on and in turn switches the contactor coil to the closed position,a fault on that lighting circuit will then show itself, because the current can then flow through the closed contacts of the contactor through the fault and pop the mcb