Does a dimmer reduce voltage?

[Bobble23]

Sorry if this is a stupid question but I've just put in a small radial lighting circuit, the last light of which is on a dimmer switch. When I measure the voltage at the light I'm only getting about 150V, even when the switch is turned up full. Is this because the dimmer is taking out some of the voltage or is it more likely I've got a loose connection or something earlier on in the circuit?

Thanks.

 

[micknew]

voltage reduced by dimmer

 

[44ALLAN]

What did you get when you tested between Neutral and earth?

 

[static zap]

Cheap Meter , has it got true RMS?

 

[micknew]

Cheap Meter , has it got true RMS?

Whats that got to do with the question?

 

[static zap]

Whats that got to do with the question?

Re: Meter ,if it was designed for Pure Sine wave,could be confused with chopped up cycles coming out of dimmer !


Is light actually Dim as well, or just reading a worry ?

 

[SYKRAPS]

Ohms law........................

 

[Silly Sausage]

A true RMS meter will calculate V[SUB]rms[/SUB], whereas a cheapo job will just display V[SUB]peak[/SUB]/sqrt(2).

As an electronic dimmer chops off part of the sine wave, a true RMS meter will display less than 230V (in this case).

 

[Badged01]

Have to agree with Archy there. The dimmer 'chops' off part of the voltage cycle but doesnt actually reduce the voltage. The voltage is aways ~230v so it depends on how your meter 'reads' voltage!.

When you have the dimmer at 'full' I would have thought you should be getting very close to 230v as none of the voltage should be 'chopped'?

 

[stuartcourt]

test voltage at dimmer and then at light if coming in 230 happy days

 

[Bobble23]

Thanks everyone. I swapped the dimmer for a normal switch and it showed 230V (haven't connected up the actual light yet) so it seems you were all right about my meter getting confused by chopped sine waves. Thanks again.

 

[bertt]

Hi,

Not likely. About AC Dimmers and/or some DCs. Thank you.
:sunny::shocked:
bertt.

 

[static zap]

(haven't connected up the actual light yet)

This is a lot of the problem ,if the dimmer had no load to work against!

STAY Safe