Why can't I mount my low voltage transformer inside?


Old 05-24-02, 12:13 AM
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Lightbulb Why can't I mount my low voltage transformer inside?

I would like to mount the transformer for my low voltage landscape lights in an unfinished area of my basement (the area has my furnace and hot water heater in it, if that is important) and run the low voltage wires outside to power my lights.

The instructions for the transformer (made my Malibu) say do not mount the transformer indoors. Their website has FAQ section that says these transformers are UL litsted as out door products and therefore cannot be used inside.

My question is "Why not?" I would think that it would be better to mount the power pack indoors where it is not exposed to the elements (water, ect.) What do you guys think?

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Old 05-24-02, 01:23 PM
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YOu are required by the NEC article 110.3.B to follow the manufacturer's instructions.

I have no clue why the transformer would not be better off inside than outside exposed to weather. To me I would think that a transfomer rated for outdoor use should be ok for indoor use.

There is a possibility that the manufacturer did not include a thermal fuse inside that transformer creating the concern of a fire hazard inside. If this is the case then you should be able to buy an inside rated transformer rated the same in volts and VA input and output replacing that outside transformer with an inside transformer. Shouldn't be too expensive.

Good Luck

Old 05-24-02, 02:57 PM
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Indoor vs Outdoor

Thank-you for the response. I would also think that if it's OK for the outdoors it should be OK inside. If it were some sort of thermal fuse/fire hazard issue, I'm not sure that I would want it on the inside OR outside of the house!
Old 05-24-02, 06:30 PM
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There are things in the code that are allowed outdoors but not indoors. The reason is almost always overheating and the risk of fire. Outdoor areas often are in a better position to dissipate heat as well. Since overheating problems outdoors are much less likely to burn your house down, the code is sometimes more lax outdoors.

I think Wg has hit upon the correct answer.
Old 11-11-09, 03:06 PM
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What did you end up doing? Did you every find out a reason for the outside installation? I would like to do the same thing.
Old 11-11-09, 05:33 PM
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Don't mean to sound discouraging, but this post is over 6 years old. I doubt that the OP is following this topic any more.

The electrical code requires that any instructions included with the product be followed. As such I would advice you to follow the instructions and mount the transformer outside.

FWIW the housing is designed for the exterior use in regards to shielding from the elements.
Old 11-12-09, 04:31 PM
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I figured it was worth a try. Just in case anyone else has the same question I emailed Malibu they replied and said, "The transformers can heat up while in use and they are recommended for outside use only." Its better to be safe then sorry.
Old 11-12-09, 05:30 PM
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It is also my understanding that transformers which are designed for outdoor use may contain materials which give off toxic fumes or thick smoke if they burn. Transformers with an indoor rating are made from safer (and more expensive) materials that don't contaminate indoor air in the event of a fire.
Old 11-12-09, 05:35 PM
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"The transformers can heat up while in use and they are recommended for outside use only."
Which translates to copper is expensive so we use the smallest gauge wire we can get away with. Just think of all the cheap doorbell transformers and wall-warts out there that are safe enough for inside use and then consider the quality that must be built into the transformers to make them unsafe for indoor use.

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