Hi Franz,

I'm still here--and it still works ok. You just need to make sure the
wattage rating of the dimmer exceeds that of the soil heating cable, and
also that the soil / sand stays damp to conduct the heat and avoid hotspots.
My cable is designed for this use at mains voltage. I admit the use of a
dimmer was my own idea--to save the cost of a thermostat. It would be best
to use a thermostat designed for the job. I think my cable was 40 feet
long. I fixed it to plastic fencing with nylon cable ties so that it kept a
snake like shape, and to prevent the coils touching when buried in the sand.
I would be more nervous of an electric blanket in bed. I may have a photo
somewhere--if your interested.

"Franz Heymann" wrote in message
...

"pronoun" wrote in message
...
Hi Amber,

You may consider building a bubble wrap dome inside the greenhouse.
I used
this to good effect last winter in a large DIY propagator with
heating
cables controlled by a lighting dimmer switch.

Unless I misunderstand you, you have a deadly system in mind, unless
you are using a transformer and low voltage cables.

[snip]

Franz