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#51343 - 04/27/05 11:25 PM Voltage drop  
Dave55  Offline
Joined: May 2004
Posts: 697
Crystal Lake, Illinois, USA
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.


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#51344 - 04/28/05 02:00 AM Re: Voltage drop  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,123
How many watts per light?

Greg Fretwell

#51345 - 04/28/05 07:59 AM Re: Voltage drop  
Trumpy  Offline

Joined: Jul 2002
Posts: 8,223
SI,New Zealand
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]

#51346 - 04/28/05 03:42 PM Re: Voltage drop  
Sandro  Offline
Joined: Dec 2001
Posts: 444
Stoney Creek, ON, Canada
Place the XFMR in a remote location and you get your VD. [Linked Image]

#51347 - 04/28/05 06:04 PM Re: Voltage drop  
Active 1  Offline
Joined: Feb 2003
Posts: 687
Grayslake IL, USA
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.


#51348 - 04/28/05 08:36 PM Re: Voltage drop  
Electric Eagle  Offline
Joined: Apr 2002
Posts: 914
Alpharetta, GA
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?

#51349 - 04/28/05 09:25 PM Re: Voltage drop  
Dave55  Offline
Joined: May 2004
Posts: 697
Crystal Lake, Illinois, USA
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.


#51350 - 04/29/05 06:15 AM Re: Voltage drop  
Active 1  Offline
Joined: Feb 2003
Posts: 687
Grayslake IL, USA
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.


#51351 - 04/29/05 03:28 PM Re: Voltage drop  
LearJet9  Offline
Joined: Apr 2005
Posts: 197
Millis, MA USA
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!!

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