Dimmer Query

[BMelectrics]

Hey All,

I installed two sets of 6 lights, each set controlled by a dimmer.

When i bypassed the dimmers, i got 240v at the end of line lights.

when the dimmers are connected, i got 208v at the end of line lights.

The dimmer switches were on full, i dont know where im losing the 32v?????


Is the a problem with the dimmer switches??


Thanks

 

[Johnuk]

no there is not

 

[BMelectrics]

no there is not

do you have a detailed explanation??

 

[BMelectrics]

no there is not

do you have a detailed explanation??

 

[Marvo]

The output waveform of the dimmer is not a sine wave, it has a very steep rising edge. The rising edge often spikes very high momentarily and immediately drops again steeply followed by a more rounded trailing edge. Your tester isn't designed to measure this type of waveform accurately, it's designed to measure nice even sine waves so take the voltage readings with a pinch of salt. Any current readings are also likely to be somewhat inaccurate especially if your ammeter isn't measuring true RMS.

 

[BMelectrics]

thank you marvo, that explains everything

 

[Marvo]

It's also worth noting I've seen cheap electrical testers that show a full dimmer output as being 20 or 30ish volts. This can be especially confusing and dangerous when you're trying to prove isolation from a light fitting. It's not uncommon for digital testers with high input resistances to show a nominal small voltage on a circuit that is fully isolated under normal conditions. The poor interpretation of the dimmer output by the tester might be mistaken for the circuit being in an isolated condition.

 

[BMelectrics]

It's also worth noting I've seen cheap electrical testers that show a full dimmer output as being 20 or 30ish volts. This can be especially confusing and dangerous when you're trying to prove isolation from a light fitting. It's not uncommon for digital testers with high input resistances to show a nominal small voltage on a circuit that is fully isolated under normal conditions. The poor interpretation of the dimmer output by the tester might be mistaken for the circuit being in an isolated condition.

there's always a curveball thrown!!