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Electrical Wiring

Low Voltage Transformer question

17 years ago

Ello All

I decided on the Seagull linear under cabinet lighting system for my kitchen. http://www.seagulllighting.com/Linear-Lighting.htm

I'm just not sure on which transformer to use. Looking to put 28-30 lampholders in with 10W bulbs so I'll need a minimum of a 300W transformer. I'll have two seperate runs of approximately 15ft each coming from the transformer located in the basement.

1) What is the difference between single output multi-tap and dual output?

2)12V or 24V?

My transformer choices are

300W Single Output 12V

300W Single Output Multi-tap 12V

500W Single Output 24V

500W Single Output Multi-tap 24V

600W Dual Output 12V

At this point I'm thinking 24V 500W and using two runs of 12/2. Any thoughts?

Thanx

D

Comments (2)

formulaross
17 years ago
The dual output transformer is two separate transformers in one housing with two separate outputs. There is the caution that you need to balance the loads on each transformer; that is, each transformer is only rated for 1/2 of the max. wattage and can't be exceeded.

The multi-tap transformers have multiple voltage outputs (24/26/28/30 for a 24V transformer) to let you compensate for voltage drop in the output wiring. Low voltage lighting typically runs at high current (thus the heavy wire used) which can lead to large voltage drop in long runs of wire. The multi-tap transformer allows one to increase the voltage at the transformer output to compensate for this voltage loss in the wiring. There is a caution from Seagull that at the first bulb in the lighting circuit the voltage should not be greater than 25V or bulb life will suffer.

The difference between bulb voltage (for the same wattage bulb) is in the current draw of the bulb. Watts = Volts x Amps, so for the same wattage bulb, using a 24 volt instead of a 12 volt bulb will cut the current (amps) drawn in half. This will also lower the voltage drop in the wiring to the bulb and may allow the use of smaller wire.

Re: "At this point I'm thinking 24V 500W and using two runs of 12/2" - With your total load of about 300W, split roughly equally into two runs, I don't see the need for a multi-tap transformer (150W at 24V is about 6 Amps which would have minimal voltage drop using 12/2) and I really don't see the need for a dual output transformner. I'd go with the 24V, 500W, single output transformer.
djincnj
Original Author
17 years ago
Thanx for responce!! Agreed, 24V 500W single output is the ticket.
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