I installed one of the sets of low-voltage under the cabinet kitchen
lights (string of 5) and I'm having problems with blowing out
The first time it went out, I checked the power before and after the
transformer. Before the transformer was good and after was nothing so
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 transformers is
blowing out. The others seem good although the lights seem to go out
sooner than I would have thought they should.
I had an electrician come infor other things and asked him about it.
No clue without doing extensive testing. Thought maybe some of the
neutrals on the breaker box may be loose and need tightening.
I'm also having some problems with other lights in the house frequently
going out soon after replacing them. Other than crappy bulbs, any
ideas on what may be causing this?
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?
all good points! The only indication of a problem is all the lights
(5) on the string go out. Not being an expert electrician; all of the
transformers and lights including bulbs are sold as a "set." When I
mentioned checking the power I just checked to see if there was power
before and after the transformer. The transformer (it's only 1x1x2 in)
is mounted on the underside of the cabinet so it's not enclosed and has
alot of air space. It's the transformer that came with the set. The
wires connecting all the lights are located between the bottom of the
original cupboards and a new bottom used to house the lights. There's
a 1/2 in space between these two for air.
I bought a new set to match the one with the bad transformer and
"spliced" in new transformer. It was the only way I could do it since
the power from wall switch comes through the back of the wall by the
underside of the cabinet.
Just could be that it's a cheap set of lights. Bought it at Lowes.
I put some of these in for a client, three sets. I notice the
transformers read 20VA. I have some other types in my own kitchen that
have wall warts the same size but these are switch mode types and read
60VA. I actually replaced one set of 3 of these with a transformer unit
thats 6 times the size but still reads 60 VA. I replaced the latter
because the cheap supplies kept blowing out, except for one which is
still working. The client wanted just one switch for all three sets so
I replaced the 3 transformers with one switchmode type supply that I
got from a local electrical distributor. As I recall it cost $80 and
supplied 150VA. They had others that supplied more at an appropriate
rise in cost.
That electrician you hired should at least have pulled the cover on the
box and inspected the neutral. I used to have a chart recorder that I
used for long term monitoring like this. I have another client that has
a similar voltage fluctuation problem. She's at the end of the feed
coming from the transformer and I can count 3 splices from the
transformer to her house. Now the problem is to convince the power
company they have a problem.
For high current needed for the brighter bulbs a transformer would need to
be physically quite large. The high cost of the copper inside and the
shipping cost adds up quickly, for higher current a switching supply is
definately more economical and if overloaded will self current limit to
prevent damage to the load or supply. A transformer on the otherhand if
overloaded will try to supply too much current, get hot and eventually fail.
Where you mount the transformer and how well the heat can escape can have a
strong effect on how quickly it would fail.
Barring voltage variation problems which are not very common, I would guess
you have used bulbs of too high wattage for the selected transformer. Don't
try and use all of the rated capacity of a transformer unless you have
mounted it in a well cooled area. If you have it shut up in a small
compartment you may need to derate its capacity by as much as 50%.
many of these "transformers" are actually switching power supplies
which is why they can make them so small and light weight
and they create radio and TV interference....
I took mine out and installed a 120 Volt lighting system...
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