Fires

[hollarda]

What usually causes fires when dealing with low voltage? Is it the transformer or the light fixtures?

[sitelights]

A buck/boost transformer without primary or secondary circuit breakers or thermal cut off can, under dead short conditions, quickly burn the insulating sheath off of low voltage conductors and create arcing leading to combustion. I have warned my suppliers about the hazards (and liability) of selling buck/boost transformers if they suspect that they will be used in landscape lighting applicatons. As a cheap and dirty power supply buck/boost transformers have some attraction to the bottom feeders in the outdoor lighting business. NEVER, NEVER use a buck/boost as a lighting transformer. The cost of retrofitting a buck/boost with primary and secondary protection far exceeds the cost of a purpose-built, UL1838-compliant power supply.

Overlamping a low voltage luminiare can also create a combustion hazard. See "underlamping : overlamping" in the lamps (light bulbs) & sockets forum. Spotlights and floodlights in the "up" position can ignite debris accumulating on the lens particularly when they are lamped to the max. I have noted that many overlamped luminaires of these types can suffer cracked lenses from the heat; these cracks in the glass lens create a prismatic effect (like a magnifying glass) that can accelerate combustion of debris such as mulch or pine needles.

The hazards associated with in-ground fixtures are detailed in the post "well lights..." in the fixtures (luminaires) forum.

There is no excuse for creating a hazardous condition. Don't believe the manufacturer's specs; err on the side of conservatism when enclosing a heater (lamps are 95% heat and 5% light) in a tight space.

The question "What usually causes fires..." sends a chill down my spine. There are no "usual" circumstances...only stupidity.