Outer Limits 4x4 Board

Quick question.
I am fitting 6 lights to my roof for a night stage of a comp, 4x50watt HIDs and 2x55watt hallogen worklights.
Will a normal 30amp relay and fuse handle it?
Or will the HIDs draw too much current at start up and blow the fuse?
310watts = 26amps but startup will be more than that.
Cheers
Paul.

> Or will the HIDs draw too much current at start up and blow the fuse
Am not sure if they will blow the single fuse; the ballasts will most likely just not startup the firing process of igniting the bulbs. The two halogens will fire up.

Theorettically your setup would handle the current based on paper-written wattage.

If you want to do everything through one fuse, I'd grab two relays, wire all six lights through the two relays, however, wire the relays in parallel so that you have 60 amps of switching, and then a single 50 amp fuse. For all of this to work successfully at a min of 11.8ish volts, your wiring will need to be 8mm or so...


Now the recommendation stuff:
First question is why do you want to depend on having everything running through the one single relay and fuse. Blow a fuse or the relay decides to pack it in (mechanical device), and you will loose all lights.
I don't think that mid-way thru a comp, you'd wanting to be changing a fuse coz everything went dark.

Would highly recommend spreading your six lights over three relays each having their own 20 amp fuses on 6mm (min) wiring. By spreading them, blow one fuse and you will still have four lights blazing.

Others will reply with a different setup, some peeps prefer a relay + fuse per ballast, however, the above suggestion is what I'd do with your setup.

Im a sparky and I agree with bushy, spreading the load over a number of fuses by running the lights in pairs will give much better protection. If the fuse is too big and only one light has a fault it will sit there and burn out b4 the fuse blows.

Run 3 relays and 3 auto reset circuit breakers and you shout have hassel free driving.

Paralleling power relay contacts isn't going to do what you expect.

In reality both will not close ( or open ) at exactly the same time - leaving the leading / trailing one doing all the work and experiencing all the electrical wear. Just use multiple relays or run one of the 60 Amp relays in the first place....

Some of the cheap HID ballasts draw a surprisingly large startup current and I've seen setups that should be OK on paper blow what are supposedly appropriate fuses. The more expensive setups ( well designed ballasts ) tend to manage startup currents better.

MightyMouse wrote:Paralleling power relay contacts isn't going to do what you expect.

I think that depends on what Bushy meant by "in parallel".

I definitely agree - two 30A relays truly in parallel is by no means equal to one 60A relay. In fact it is really only equal to one 30A relay. The relay that opens second (or closes first) cops the whole current load. This is a common mistake my old man drummed into me years ago.

But if you are running the two relays to three lights each, then you are okay.

Personally, I would agree with the three relays, separately fused option, each relay going to a pair of lights.

Agree chimpy... thats why I specified "contacts" but agree that in this case Bushy was probably using paralleling in the sense of breaking up.

Also if you have a problem with "distributed" systems you don't loose all your lights - a fairly unforgettable experience.