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Posted By: Dave55 Voltage drop - 04/28/05 03:25 AM
I installed a Juno transformer for 5 puck-type undercabinet lights. The secondary of the transformer is 13.8 volts. I'd like to drop it to 11.8 volts for bulb life. Can I add a resistor or something else. If so what size & where will I find it. Thanks.

Dave
Posted By: gfretwell Re: Voltage drop - 04/28/05 06:00 AM
How many watts per light?
Posted By: Trumpy Re: Voltage drop - 04/28/05 11:59 AM
Dave is that voltage measured under load or by the open-circuited secondary winding?.
2V is a fair bit to "drop" in a case like this and I don't personally think a resistor would be suitable for this sort of application.
Any power "lost" would be dissipated as heat.
I'm assuming you are using fittings with the small Halogen burner lamps in them, if they are 12V lamps, should it make any difference?.
I was under the impression that these lamps have a reasonably short life anyway. [Linked Image]
Posted By: Sandro Re: Voltage drop - 04/28/05 07:42 PM
Place the XFMR in a remote location and you get your VD. [Linked Image]
Posted By: Active 1 Re: Voltage drop - 04/28/05 10:04 PM
Hey Dave,
Some of those Juno electronic transformers burn out faster than the bulbs.

I have almost lost a good customer over them puck light because of short bulb life. The customer had 50-75 of them done by cabnet people. Could not be dimmed easily because they were on the same switch other types of lights. They kept them on all day and 1/2 the night. Customer was angry because we came out every 8 weeks to change bulbs or pucks.

Besides the transformers and bulbs going bad sometimes the bulb sockets make a bad connection to the bulb.

My advice stay away from pucks and use under cabnet lights with 120v bulbs. Also Juno trac 12 or similar with magnetic transformers is good.

Tom
Posted By: Electric Eagle Re: Voltage drop - 04/29/05 12:36 AM
Just add about 15 ft of wire and you'll easily lose those pesky extra volts.

Is your measurement at the transformer or at the Pucks?
Posted By: Dave55 Re: Voltage drop - 04/29/05 01:25 AM
Thanks guys. The lights are five 20 watt halogen pucks. I measured it with the open secondary. The customer says the lights are noticably brighter, and the Juno trancformer is a magnetic 1500 watt. It had an additional wire for the primary to boost the voltage if needed.

Dave
Posted By: Active 1 Re: Voltage drop - 04/29/05 10:15 AM
Are you sure it's not a 150w transformer?

With a load the it's probibly fine. Just tell the customer they have a better transformer now. If they want it dimmed sell them a magnetic dimmer.

Tom
Posted By: LearJet9 Re: Voltage drop - 04/29/05 07:28 PM
Active - Please!! Bite your tongue. We have several commercial customers that use dozens of those Alexandra or WAC puc lights in thier stores. We are at one store or another once or twice a week for lamp/puc replacement. I hope they dismiss your suggestion as silly. Let's keep those beautiful puc lights!!
Bill
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