Pls see inline:
:I installed one of the sets of low-voltage under the cabinet
: lights (string of 5) and I'm having problems with blowing out
===> HOW are the transformers "blowing out"? Simply stops
working? Smokes? Pops?
: The first time it went out, I checked the power before and
: transformer. Before the transformer was good and after was
: I replaced the transformer (had to buy a new set of lights) and
: everything worked OK.
: About 2 weeks later the lights were out again.
: I have a few sets of these lights and only one set of
: blowing out. The others seem good although the lights seem to
: sooner than I would have thought they should.
===> Something doesn't sound right in either: # & type of bulbs
used, transformer rating/size, xfmr location (no air flow), or
applied primary voltage.
: I had an electrician come infor other things and asked him
: No clue without doing extensive testing.
===> Interpret that as "don't want to bother with it" or "you
won't pay me what it;s worth". Whatever, it doesn't require
Thought maybe some of the
: neutrals on the breaker box may be loose and need tightening.
===> That was blowing the transformers? Not very likely. It
sound like maybe he had a no-fault-found service call and just
wanted to move on.
: I'm also having some problems with other lights in the house
: going out soon after replacing them. Other than crappy bulbs,
: ideas on what may be causing this?
===> Maybe crappy bulbs if you're buying them all at the cheapest
location you can find and they're no-names.
Another possiblity though is that your house voltage is either
high all the time or goes high for long periods of time. THAT
might amount to a little work to dig thru if it's intermittantly
high voltages, but ... it's pretty easy to figure out in some
ways, not always.
What did you measure at the input to the transformer? It should
have been around 115 to about 122 volts. If it's 126Vac or more,
then it's a high power into the house causing the bulbs to burn
out quickly and, if the design were poor enough, might, not will,
explain why transformers might give up. There is probably a fuse
internal to the transformers which opens up. Not replaceable so
don't even look; they're internal to the windings.
Do you have the right number of bulbs for the transformer you are
Is the xfmr the one intended for that number of bulbs?
What wattage are the bulbs?
What voltage are the bulbs?
What are the ratings on the transformer? It should be printed
right on it.
Do you ever notice any other lights going bright or dim in the
house? Like when an electric motor starts.
It's possible, with a cheapie sysem, that one bulb blowing could
cause damage to the transformer under "normal" voltages. Is
there always a blown bulb when the xfmr goes bad?