Ordinary triac lamp dimmer


Thread Starter


Can one run a ordinary triac lamp dimmer between two phases, thus without a neutral? The 2 phases are 120gr. out of phase, as they should, the voltage is then 220V. Each phase meausures 110V against neutral.


Johan Bengtsson

The circuit doesn't care and will work fine as long as the voltage isn't too high for it (it needs to be able to handle the peak voltage of your 220V AC - of course).

There might be an issue about if this is legal where you intend to install it however, and if it will be safe or not (the later depends on how grounding and so on are done).

/Johan Bengtsson
Yes, you can.

You use the other phase as your "neutral", BUT all the parts need to be good for min 400V and make sure there are NO metal parts exposed and to use a non metallic shaft for the potentiometer (most knobs have a small metal set screw and you can touch these).

Be careful when working with these of applications, you may survive a shock but the feeling is rather unpleasant.

Hope this helps.

Carel Colpa
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