Electonic Low Voltage Monorail Light with melting wires. Please Help!

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Old 12-13-10, 04:33 PM
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Electonic Low Voltage Monorail Light with melting wires. Please Help!

I could smell the odor of something electrical burning. I removed the transformer and the wires to the transformer were melted. I installed a new transformer unit and after about a month the same thing occured. No fixture heads were added to the original light package. I did not change out the rail or the fixtures after the problem occured. I tested the line voltage in at roughly 125v. What could be causing this problem? Thanks!
 
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Old 12-13-10, 04:41 PM
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I removed the transformer and the wires to the transformer were melted.
120v wires or the low voltage wires? Is the transformer in free air or in an enclosed space?
 
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Old 12-13-10, 05:27 PM
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Transformer wires. The housing is not in an enclosed location.
 
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Old 12-13-10, 05:30 PM
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Actually, I'll have to take a look at the unit again. They could be the low voltage wires off of the transformer.
 
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Old 12-13-10, 06:08 PM
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The monorail is drawing too much current. Make sure you are not overloading it with too many fixtures and that each fixture does not exceed the maximum allowable wattage.
 
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Old 12-14-10, 05:11 AM
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This can happen even if the transformer is loaded to its rated capacity. Ideally it should have 20% headroom so it doesn't heat up. In other words, if you have a 200-watt xformer you should not put ten 20-watt lamps on it. Eight lamps would be 160 watts, which gives you the 20% headroom.
 
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Old 12-14-10, 06:20 AM
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The light is assembled as purchased (bulbs included). No additional heads were installed. I installed two units, but only one has this problem. Could the problem be with the rail or one of the fixture heads themselves?
 
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Old 12-14-10, 10:52 AM
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Please read Rick's post. Regardless of how many heads came with the kit if the wires are melting on the secondary side most likely is too much load. Maybe it came with extra heads or you put too large a replacement bulb in one or more heads.

You still though haven't told us if it is the primary side or secondary side that is melting. We also need to know the watts or volt-amps the transformer is rated for and the total wattage of the bulbs.

One quick test is after it has been on for a couple of hours touch the transformer. Can you count to 10 without burning your fingers?

My guess/opinion since the last one lasted six months is cheaply made transformer. Reducing the load by one or two heads though might make for a longer lasting transformer. Or maybe keep all the heads and use a higher wattage transformer.

The heads abd rails are just conductors. It is unlikely they are the problem. A short between the rails or in the head would cause immediate transformer failure.

Do you know if the transformers have built in overload protection? If so maybe that is what is failing.
 
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Old 12-14-10, 02:01 PM
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Loose connections can also cause the leads (wires) to heat. Under heavy loads, the on/off heat/cool cycling can loosen the connections. Re-seat them by pulling them off and putting them back on.

If the wires are damaged by heat, re-seating probably won't help. The only option may be to replace the transformer.
 
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Old 12-14-10, 02:55 PM
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Rick Wrote:
Loose connections can also cause the leads (wires) to heat. Under heavy loads, the on/off heat/cool cycling can loosen the connections. Re-seat them by pulling them off and putting them back on.
And I would add check where the heads fit in the rails. Are they loose. Remove the head, any sign of scorch marks on the rail or head?
 
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Old 12-16-10, 07:51 AM
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The wires have melted on the low voltage side of the transformer. I will check all of the contacts, reduce the unit by one head, and try again. I do believe that the transformer is cheaply made. Since I have replaced the tranformer on this rail twice and have a few other units that have had no problems, perhaps it is a problem with the contacts. The bulbs are all rated for the unit, and were included in the kit as well.
 
 

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