why do power packs get hot when plugged in, but not being used?

i was wondering why do power packs get hot when not in use?

It is probably the Transformer in it that is just changing power to the correct voltage and then then power not goinging any where. I Think.

ah yes, but if there is no circut, how do they still get hot?

Take my advice. Just unplug it when not in use. I had a house fire start be an appliance that wasn’t in use, it was just plugged in.

The transformer passes ac current at all times, resonance in the windings create resistance which is turned to heat. Simple explanation I’m no enginner although I played one on TV. [(-D][(-D][(-D]

Ah, but there is a circuit. The input transformer for the mains is a complete circuit and this is the part that heats up.

See following link for some diagrams:
http://www.kpsec.freeuk.com/powersup.htm

A power pack starts with an AC transformer. The AC current from the wall is a sine wave, continuously rising and falling. Inside the transformer, this creates a magnetic field, constantly building up and breaking down. This causes some movement of the metallic elements in the coils, resulting in both heat and the characteristic “hum” that transformers make. As I recall from a few weeks working in a transformer manufacturing plant back in 1969, this is called “magneto-striction.”

ditto couldn’t say it better.

Yep , I use a ten outlet Strip rated at 30 amps, just for my control power and lighting.[:D]

Because North America uses 120AC Vs 240AC in many other places.

Same reason a North America kettle lead get hots when the kettle is boiling yet it stays cool elsewhere in the world.

I read somewhere that transformers and power supplies and the like are HUGE energy hogs in America as they still suck juice even when not being used but still plugged in to an outlet

All power packs i.e. transformers use a low % of the rated output at all times. The cheaper the transformer the less efficient. If your pack is “HOT” you may have a problem. All packs will be “warm” at no load. Do you have any load on the accessary terminals?

Gotta love Sine waves.