Low voltage lights - voltage drop/cable size
 

Have trawled through groups but can't find a definitive answer to my
question.

I have a 60W transformer and want to run 3 x 20W low voltage lamps from
this.

The transformer is "terminated" having three sets of terminals built in
so I can connect cables to each 20W light.

The cable running to each light is 1.5m long.

For cable size calculations do I need to take the total load of 60W (3
x 20W) and the total cable length (3 x 1.5m lenghts = 4.5) or simply
the load for each light (20W) and the cable length to that light(1.5m).

Using TLC's Low Voltage Lighting Cable Selector, I get a cable size of
2.5mm for the first way, and 1.0mm doing it the other way.

Which is correct?

TLC have a note at the end that says: The actual cable size and runs
required to connect several lamps to the same transformer output must
be equal to or greater than total load of the run

....but I think this refers to a single output where one cable runs to a
junction box serving several lights.

Low voltage lights - voltage drop/cable size
 

In article .com,
says...
Have trawled through groups but can't find a definitive answer to my
question.

I have a 60W transformer and want to run 3 x 20W low voltage lamps from
this.

The transformer is "terminated" having three sets of terminals built in
so I can connect cables to each 20W light.

The cable running to each light is 1.5m long.

For cable size calculations do I need to take the total load of 60W (3
x 20W) and the total cable length (3 x 1.5m lenghts = 4.5) or simply
the load for each light (20W) and the cable length to that light(1.5m).

Using TLC's Low Voltage Lighting Cable Selector, I get a cable size of
2.5mm for the first way, and 1.0mm doing it the other way.

Which is correct?

TLC have a note at the end that says: The actual cable size and runs
required to connect several lamps to the same transformer output must
be equal to or greater than total load of the run

...but I think this refers to a single output where one cable runs to a
junction box serving several lights.



If you are running seperate feeds from the tranny to each light, then you
just need to size the cable for that one lamp - so you are correct with
the 1.0mm. If you were daisy chaining the lamps, then you would need to
use the larger cable - maybe going 2.5mm to the first lamp, then 1.5,
then 1.0!

Low voltage lights - voltage drop/cable size
 

For cable size calculations do I need to take the total load of 60W (3
x 20W) and the total cable length (3 x 1.5m lenghts = 4.5) or simply
the load for each light (20W) and the cable length to that light(1.5m).

With seperate runs, just take the 20W and 1.5m. However, I'd run LV in 2.5mm
anyway. It's not expensive or difficult to work with and will reduce voltage
drop.

Christian.