Insulation Melted On Cables

[Guest]

I was finishing up a job yesterday when the customers friend called in and asked me would I replace a battery for them. I agreed and said that I would call around when I finished up.

Got there and seen the Battery Fault Call Engineer message so I proceeded to replace the battery but when I removed the cover I noticed that all the wires connecting to the zone inputs were melted and some were shorting each other out. The wires came in at the top and the battery was at the bottom along with the trafo.

The panel was an Astec, it's not available in the UK and is a two wire system. Two wires for the bell, two wires for the keypad etc and two wires for the zones. pirs included. I have heard of this once before but never seen it first hand. I got a call a few years back about a europlex verifier with smoke coming out of it and that all the wires were melted, never called me back

Any ideas what would cause this

Jim

the 2 wire systems ive seen, work on reversed polarity..so id guess its a short somewhere on the board..not knowing the panel,its a guess...

[jnealon]

I called the manufacturer today and he never came across this before. The only explanation that he could come up with was that some of the battery acid came in contact with the board causing a short and current to flow through the zone terminals.

If battery acid came in contact with the board would it not destroy the tracks on the board.

Anyway he offered to call out himself and replace the panel for free even though the panel was 4 years old.

[arfur mo]

i would be more suspicious of the battery getting very hot combined with some very poor quality or faulty cable used.

sometimes in manufacture, the cores sleeving gets 'cooked' and simply peels of the the strands, for some reason especially the yellow core gets the worst of it perhaps its the pimentation used?. have a look inside the detectors and door contacts to see if the cable insulation is naff here! if so its better to run new cables.

[whistle]

I have also Flashed many a bell unit on a rip out in a town centre when i cant be arced to walk miles to get my ladders off.

Edited due to public forum.

[Axejacket]

The only explanation that he could come up with was that some of the battery acid came in contact with the board causing a short and current to flow through the zone terminals.

If battery acid came in contact with the board would it not destroy the tracks on the board.

J,

I have seen similar but not in a panel; twas when I used to be involved with the radio (PMR) side of the industry. If the pressure in the battery exceeds the valve, it will "mist" the so called sealed contents through any available breach in the outer case. This may come from a fault on the panel incorrectly charging the battery. The residue will be fine and not initially visible. The connector strip may only appear dull and not be noticably damaged... dunno! I've seen it lightly melt sheathing (Orange peel effect) but as for comparable damage to the PCB, usually they are laquered or dipped and even at worst will react with the acid much less (after all they have to resist the etching process) than the vulnerable plastic coat of the conductor so seemingly appearing to be untouched.

Only an observation from previous unusuall battery balls-ups and may not be the problem in your case.

I know this is late now, but check you're charging rates and try a new battery.

.

[C&DSecurity]

Could be the cables not terminated properly (LOOSE)

If this was a Distribution board

You would get melting of the insulation at the terminal

as the power was being drawn.

Just a thought

And before you say it

i know its a intruder alarm not a Db but the princibles the same.

[Guest ALSEC]

I have also Flashed many a bell unit on a rip out in a town centre when i cant be arced to walk miles to get my ladders off.

Edited due to public forum.

Just let it ring..