Fusing low voltage lighting

[mdshunk]

If I was to use a buck-boost transformer (120/240 primary, 12/24 secondary) to power many banks of low voltage accent lighting, am I required to fuse each conductor run from the secondary side?

 

[iwire]

Re: Fusing low voltage lighting

You will have to rethink that.

411.2 Definition.
Lighting Systems Operating at 30 Volts or Less. A lighting system consisting of an isolating power supply operating at 30 volts (42.4 volts peak) or less, under any load condition, with one or more secondary circuits, each limited to 25 amperes maximum, supplying luminaires (lighting fixtures) and associated equipment identified for the use.

411.3 Listing Required.
Lighting systems operating at 30 volts or less shall be listed for the purpose.

You need to use a listed low voltage lighting transformer.

 

[mdshunk]

Re: Fusing low voltage lighting

So whereas my proposed transformer is a "POWER AND GENERAL PURPOSE TRANSFORMERS, DRY TYPE (XQNX)", I'd be okay since the transformer being used to supply 12 volts at it's rated load, and the lights are UL listed for use as lights? or no? There doesn't seem to be any prohibition on the use of a general purpose xfmr. Show me the error of my ways if I'm mixed up.

 

[iwire]

Re: Fusing low voltage lighting

No you may not use a general purpose transformer unless it is also listed as a low voltage lighting power supply.

Read the definition of a Low voltage lighting system and you see it includes the power supply.

Then read 411.3 and you see that the entire system must be listed for the purpose.

You have to remember that at 12 volts the current adds up quickly.

The NEC limits each low voltage lighting circuit to 300 wats which is 25 amps at 12 volts.

The listed power supplies will have the proper overcurrent protection already installed.


Check out this article

IAEI Low-Voltage Lighting Systems

 

[mdshunk]

Re: Fusing low voltage lighting

I appreciate that link. It cleared it all up for me. In fact, they mention the buck-boost transformer idea of mine in the article specifically. It must have been tried before.

Thanks again.