Quick relay question.

[La Poste]

Greetings.

My cousin has an electric garage door, it's a roller shutter that is operated by remote control.
He was asking if it is possible to wire the garage lights to this shutter so that when the door opens the garage lights come on.
The garage has three 6ft fluorescent lights each with two 70Watt bulbs in them totalling 42 Watts.

The shutter itself has a small light attached to it that switches on as the shutter is opening and I think it has a timer installed to switch this light off let's say 2 minutes after the door has closed.

I am thinking the best way to do this would be with a relay, a din rail mounted relay to be precise.
I am no expert on this subject.

The lights would also be switchable from wall switches and so I was thinking of putting the wall switches in parallel with the shutter door light supply, that way if the shutter is closed the lights can be switched on and off from the wall switch. That means the lights will have two supplies, one from the shutter door light supply via the relay and one from the switch.

The door is quite pricey so I don't want to blow anything up, the PCB that controls the door has an output for a light but is restricted to a small light and I would not want to put six 70 Watt bulbs across it what with them being inductive loads and all, I might blow the PCB.

So reading this am I on the right track?
Is mixing the supplies to the lights like this a really bad idea?

Thanks.

 

[Deleted member 9648]

I would be inclined to feed the flu's through a contactor energised by the wall switches...and use a relay energised by the garage door light,with the N/O contact paralleled with the wall switches,that way you are keeping the lighting circuit and garage door gear completely separate....and you are not switching the full lighting load through the relay,but the more suitable contactor.

 

[La Poste]

So the contactor would feed the lights as one supply and the relay would feed the lights as the other, is that what you are saying?

 

[telectrix]

and check the voltage of the garage door integral light so as to get the right relay ( it could be 12v or 24v )

 

[La Poste]

Thanks people, this is my first voyage into relay territory and dual supplies, this is all new to me.
They don't really teach this at college.

 

[Knobhead]

Once you have the door light voltage and if it’s AC or DC then it’s fairly simple. No need for contactors just an octal base relay, you can get them up to 10A rating. The switch in parallel with the relay and the jobs done.