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nbachert

Well Known Member
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I have my power line for the landing lights go from the VPX to a terminal block, from there a single wire goes out each wing, at the wing tip I split it into two and attached it to both 75w bulbs. I also buttspliced the grounds of each light together and ran a single wire to the outboard rib which I secured with a ring terminal on a nutplate. When I turn on the landing lights which have a 15a breaker, they don't come on because the VPX is tripping them. Here is where I'm lost. As begin trouble shooting, the wires check out and are not grounded. If I disconnect one light at the wingtip, the other light will turn on. All four lights work individually this way so I know its not the bulbs. Then I put a single light from each wingtip on one power wire at the terminal block and they both came on drawing 11.24 amps. So can anyone tell me why I can power two lights in opposite wingtips but I cannot power two lights in the same wingtip. Thanks,

Nick
 
Haven't got / understood the complete setup you have used. But 4x75W is ~25A? So your 15A breaker seems too small for 3 bulbs, let alone 4?

As an aside, when we wired this we used 12awg wire per bulb, with a 15A CB per pair of lights. Whilst some of that wiring size was not absolute, but to avoid voltage loss over distance, what size wire do you have out of the VPX?

To debug the system, you could go out and buy some lower W bulbs - even over here they are only a couple of ?. It might be the VPX is seeing a high start current or similar?
 
Since one side works and the other doesn't, swap them at the VPX and see if the problem stays on the same VPX circuit or follows the lights currently tripping the breaker.

If the problem follows the light, you probably are experiencing a spike higher than 15a at startup. Depending on the quality of your VOM, you may not be able to measure the spike. If the problem stays, you may have a problem with that VPX circuit.

In either case, I would give Chad Jensen a call.
 
From the wording in your post, it sounds like you have all four of these lights on a single pin, so there wouldn't be any way to swap pins at the VPX.

Regardless of that, 4 75w lights on a single pin won't work...two at most. With four bulbs, you are drawing A LOT of current with all on.

Can you send me your configuration through the online planner?

Also, by using a single pin and wire to run the lights, you are losing the wig-wag function of the VPX. I would really like to see your setup though.
 
on a bulb, or any heat device, start up amps will always be higher than running amps, just for a few milliseconds. Try to power up without the box using an inline fuse for troubleshooting.
 
I was testing 2 lamps with a 12v, 10A power supply. I never could get the lights to work because they kept tripping the safety on the power supply.

When I used a battery, they worked. I measured the steady current at 6 amps.

My guess is, as others have stated, that the startup current is over 10 amps for 2 lights. So the implication would be that with all 4 lamps, you could be going over 20 amps on startup and then they would settle in at 12 amps continuous draw.
 
I don't have VPX but have a VP-50 and I suspect the situation is roughly the same. You have to run a separate wire to each wing from the control unit pins -- one pin for each wire -- (or to a terminal block if that's what you're doing). And then on my VP-50, I route the two pins to a single switch.

At the time, I confirmed with Marc Ausman that this is the way to go.
 
Problem solved

The initial post was the layout for one wing which has two lights. It seems the initial surge of power for two 75w bulbs is greater than 15amps which is why the VPX was tripping. I found a 50w bulb and replaced one of the 75w bulbs on each side and both sides are working now. Thanks

Nick
 
For an incandescent lamp the inrush current for a cold foil meant can be 10-15 times the steady state value. I don't know how the Vx deals with it but unless it has some sort of delay on over amperage trip it is probably doing the same thing your bench power supply did. The spike only lasts a few milliseconds so something like a battery doesn't care.
 
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