Batboard

looking for some help with a fed sig light bar in my type 6 brush truck/rescue at work. We have a 99' ford f-550 that was purchased from central states equipment. The light bar on it is a "ADL series B" from what I can tell. The problem is the light bar is turning off while running code and at a stand still like an MVA. We do have a load manager on this truck. This truck has new batteries and a new altenator on it and is putting out the voltage within specs. Today while doing morning truck checks the light bar would not turn on, so I checked the fuse compartment and found the fuse was fried, along with the slots (fuse has 4 prongs) in the fuse pannel. My question I guess is could the load manager be messing up?, or the wrong fuse? we have been using the same fuse number that the truck came with. We don't have a shop to take this truck to all repairs are done "in house". Any info anyone can get me on this would be great as I see this a major safety issue we have. TIA.

That sounds like either your drawing too much for the fuse/holder, or you have an intermittent short somewhere. Do a continuity check from the bar side of the fuse slot to ground with the fuse pulled, and if there's no continuity, check the wire run for rubs.

Finally, if all that checks out ok, figure out how much power you are drawing with the unit on- most rotators are 55w each, flashers and alley sweeps are (usually) 35w each. Take the total wattage of all the lights and divide it by 12- this will give you the amperage draw you have. If your fuse is at or near this rating (within 3amps), you need a slightly higher rated fuse. If you're over by a bit, go to a smaller fuse.

Do you have a circuit breaker inline between the fuse panel and battery?

I don't think its the load manager messing up, I'm leanin to the same thought that Rick is, that your lightbar is drawing a hair too much power

Amperage is drawn, not supplied like voltage. Overvoltage typically doesn't cause burnt fuse holders & fuses or anything like that, it would cause your rotators to turn faster, lights to burn brighter or possibly pop.

The fact that you have a melted or charred fuse holder is an indication of either a short at the fuse holder itself, a short distal to the fuse holder (toward or in the equipment being protected) and failure or malfunction of the fuse / circuit breaker itself.

I would be tearing the light bar apart. Hook the lightbar up to an outside 13.8v power source and check voltages at each rotator motor and bulb. I'd then pull one side of each motor and one by one place an ammeter in-line and watch the meter while running. Analog meters work better for this since needle deflection will show sudden current draws where digital meters may average it out.

I'd also be questioning the cabling to the lightbar itself. Check that good too.

NB2E, Ric

drop the fed sig get a whelen

KitN1MCC wrote:drop the fed sig get a whelen

trust me I am trying to sell that to the chief! Anyone have any recommendations for a LED bar that would work on this truck. Would need a 48" and not real expensive. I will look at the truck again on monday when I go back to work.

I think Ric needs to re-think what he has said here just a tad
bit. The normal cause for a fuse holder to melt is not from a
short, but from heat. The heat takes time to build up. You
don't get heat in the time it takes for a short to pop a fuse.
Don't waste your time looking for a ghost problem. High
current and a poor fuse holder is the issue here.

This over heatinging of a fuse holder is normally caused by a
loose or poor connection. It causes the connection to have
tiny amounts of arcing between the metal parts. As the
arcing gets more pronounced, the resistance of the
connection goes up and the connection arcs even more. The
more the connection arcs, the more heat it generates and so
on. It becomes a runaway problem in just a short time.

The solution to the melted fuse holder is to prevent the arcing
in the first place. You can do this by using a higher current
rated fuse holder with a larger fuse. You can split the load
and use several fuses. This may not be a bad idea. You can go
to a different style fuse holder that has better spring tension
in the connections.

The older radio techs on here may remmember when Motorola
first came out with their black inline fuses for the 100 watt
radios. They were always making a bad connection and
causing transmitter problems. You had to cut the heavy red
wire and crimp these fuse holders in line. If you didn't screw
on the cap real tight, you would get the loose connection heat
in a short time of use. They sure wouldn't hold up to the
current of a light bar. A 30 amp fuse was almost too much
for them.

Jim

NB2E wrote:Amperage is drawn, not supplied like voltage. Overvoltage typically doesn't cause burnt fuse holders & fuses or anything like that, it would cause your rotators to turn faster, lights to burn brighter or possibly pop.

The fact that you have a melted or charred fuse holder is an indication of either a short at the fuse holder itself, a short distal to the fuse holder (toward or in the equipment being protected) and failure or malfunction of the fuse / circuit breaker itself.


NB2E, Ric

you need a 52/54 inch bar

i have heard of Fed sig stuff just doing weird stuff at times

48 will work too, as this is mounted on top of the rescue box. I didn't have a chance to look at the light bar today as this truck is at a different station than I am. Too many calls today. Thanks for all the info ya'll have given me so far.