LED transformers

JoeNorm

Senior Member
Location
WA
I am planning some LED strip lights in a kitchen. There will be a switch leg to an over-sink area and another switch leg to under-cabinet area. The driver(s) will be in the cabinet above the range hood.

I have a couple questions: I am assuming the driver is within the switch-leg, is this correct?

Do I have to have two separate driver/transformers for each leg? Or are there units with multiple inputs and outputs?

thanks
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
You can driver multiple strings of LEDs off one transformer if it is sufficiently large. The voltage drop on the wiring and in the string itself is significant. There will be a noticeable drop in brightness on long strings. To alleviate that, you can feed both ends of a string or break it into smaller strings fed by larger wires.
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
I usually use jacketed speaker wire. Colored for DC, available in different gauges, and in-wall rated.
I got dinged by an inspector for using speaker wire because it's not labeled on the jacket. I now use thermostat wire which is labeled as CL2.
14/2 would be overkill unless it's a very long run.
 

Knuckle Dragger

Master Electrician Electrical Contractor 01752
Location
Marlborough, Massachusetts USA
Occupation
Electrical Contractor
Some drivers have multiple outputs but you can also T- off the load side of a driver, try to keep the runs equal lengths as possible.
I use 14/2 alot of the time. It's readily available in the truck and it won't break the bank. Typically the runs a relatively short.
If I were concerned about V drop I would get a stranded low energy wire on the idea of what Larry uses.
 

RDean

Member
Location
Madison, WI
Occupation
Warranty Service. Residential lighting
When LED lighting first arrived on the scene, like any other low voltage item, the default voltage was 12 Volt. Now many LED vendors also make an equal in 24 Volt. 24 Volt LED tape will allow you to double your run length as well as allow you to have a greater distance between your driver and load. Just remember, just because your dealing with low voltage doesn't mean that Ohms Law doesn't apply. Always consider the your load and do the appropriate calcs for wire size. It s even more important when wiring for incandescent loads. Whenever possible on long runs between your driver and load, use stranded wire to take advantage of skin effect and reduce voltage drop.

The above wiring techniques for loading drivers suggested above work fine. Always use the vendor's driver and don't skimp to save money. Always follow the vendor's recommendations for dimming and note that drivers come in dimmable and non-dimmable versions.

Lastly dimming. This sometimes can be a miss or hit proposition. Unless it's necessary to to have a range of lighting options, select the light level you will be mostly needing. Sometimes dimming can lead to flickering or strobing which can be a bugger to sort out in residential applications. This can be true even when supplying a vendor recommended dimmer.
 
Top