Outdoor low voltage transformer not working

I have a transformer (malibu, 120V to 12V, supports 300W worth of fixtures) that works ok when I plug it into an outlet inside my home (2 different outlets, one gfci, the other not), but when it's connected to the outside outlet that I want to use (GFCI) it doesn't work. I know it's working inside, as I get 12V ac on the multimeter from the outputs.

I've triple checked the outside outlet, getting ~122-123V using a multimeter, I have an outdoor water sprinkler timer hooked up to it which works fine, and I've confirmed that the gfci isn't tripped.

Is there some kind of eletrical property aside from voltage that transformers are sensitive to? My multimeter has an ohms function on it, but I don't know enough about ohms to use it.

Thanks.

 

There are a number of possibilities. Perhaps the half of the receptacle the sprinkler controller is plugged into works, but the other half does not. Perhaps the sprinkler controller is running on battery backup. Perhaps the outlet is controlled by a photocell and is only live at night and running on battery backup during the day. Perhaps it's controlled by a switch.

Conduct some experiments. First, put away the multimeter. There's just too many ways to fool it. Take a table or floor lamp out there and plug it into both halves of the receptacle. If the lamp comes on at full intensity, then there is no reason that the malibu lights should not also work. Perhaps there is an intermittent connection in the malibu wiring and just moving it around affects its operation.

 

Yeah, I've tried both the top and bottom receptacles, and both appear to be working ok. The sprinkler timer has an indicator icon on the lcd panel if the power is cut off and it's running on battery backup. I've used this outdoor outlet for a fair amount of temporary stuff, and I'm pretty confident it isn't on a switch, timer or photocell.

I haven't tried testing w/ a lamp, I'll do that tonite. Malibu has tech support open now, so I think I'll give them a call too. I'll post back what I find.

Thanks.

 

It could be that the receptacle is old and worn and is not connecting with your transformer. Sometimes the receptacles just loose the spring tension and need to be replaced.

 

most of these transformers *do* have a photocell - look on the sides, a few inches above the bottom, for a dark plastic dome about 3/4 inch (from memory in my previous home). drove me crazy until i read the manual. go to malibu's web site?