Bucking Transformer: Constant power-on OK?

[toxcrusadr]

Is a vibrating power transformer consuming power? More to the point, is it OK to have line voltage to a bucking transformer on all the time, or is it better to power it off completely when not in use?

My shop building in the woods has high line voltage. We run Christmas lights to the outhouse. The strings have been burning out too fast, so I set up a 120 - 15V (2A) transformer as a bucking transformer to bring the voltage down from 125 to 110. I mounted it in a junction box and used it to power one socket of a duplex outlet. Works fine. I ran it for awhile and did not notice any heat buildup on the outside of the J-box so I think I did it right.

However, there is a slight hum even when the lights are unplugged. Typical physical hum from vibrating laminations. I went ahead and shut off the circuit at the breaker box just to be sure I didn't burn down the building until I could check it out.

Is there any risk, or power consumption, from leaving it powered up?

 

[gadget73]

it does waste some power being connected all the time. I'd probably switch it off when not in use just because I'm cheap and hate sending extra nickles to the power company. I might also wire in a fuse right at the transformer, say 3 amps or so, to make sure that the circuit opens in case something went bad with the transformer. Figuring it could seriously melt down before a 15 or 20 amp breaker pops.

 

[toxcrusadr]

Good point. It's always possible someone could plug in the wrong thing into that outlet and draw way more current than the xmfr can handle.

 

[big2bird]

Is a vibrating power transformer consuming power? More to the point, is it OK to have line voltage to a bucking transformer on all the time, or is it better to power it off completely when not in use?

My shop building in the woods has high line voltage. We run Christmas lights to the outhouse. The strings have been burning out too fast, so I set up a 120 - 15V (2A) transformer as a bucking transformer to bring the voltage down from 125 to 110. I mounted it in a junction box and used it to power one socket of a duplex outlet. Works fine. I ran it for awhile and did not notice any heat buildup on the outside of the J-box so I think I did it right.

However, there is a slight hum even when the lights are unplugged. Typical physical hum from vibrating laminations. I went ahead and shut off the circuit at the breaker box just to be sure I didn't burn down the building until I could check it out.

Is there any risk, or power consumption, from leaving it powered up?

It does have parasitic loss with no load. As for protection, it depends on the KVA as to whether the circuit CB protects it as well.

 

[Trio]

It is also dissipating the energy primarily as heat. best to shut it off when not in use.

The new "retro" look all in one stereo's as well as some of the more conventional looking "all in one" stereos- they do not switch off the AC on the primary, instead they switch the power off at the secondary, and while this may be acceptable to UL, I would never allow it in my house unmodified or otherwise left unable to shut off AC to the primary.

 

[mech986]