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AuthorMessage
TrevorW1
TrevorW1

Posted: Sun Jan 31, 2016 4:55pm

Post Subject: Light switches

Hi Tony. The bedroom of our boat has two 12v spotlights connected to a 2 gang switch. Both lights are wired to one switch so I decided it would be better if we could have them working independantly, however, changing the wiring showed that one side of the switch isn't working (hence both being wired to one I suppose) so a new switch is needed. My question is will a 'normal' 240V switch from my local DIY shop work with a 12V system. I seem to remember reading somewhere that it won't?

nbpippin
nbpippin

Posted: Sun Jan 31, 2016 8:27pm

Post Subject: Light switches

Yes, a domestic switch designed for 220v working is fine on 12v, however check the current rating. A 6a switch means only 72w on a 12v system. Also check the switch is AC/DC, most are.

Tony-B
Tony-B

Posted: Wed Feb 03, 2016 1:18pm

Post Subject: Light switches

I am sorry that I did not notice that I had not replied to your question until today. The true answer is not as clear cut as the other answer suggests. It is, however, true that mains (240V AC) switches usually give no problems on 12V DC lighting circuits but no one can guarantee that will be so in every case. When any switch is opened a spark tries to jump between the two opening contacts. On a DC circuit the spark will keep going until the gap is too large for 12 volts to push a spark through ionised air. On an AC mains the current turns itself off every 100th of a second so the spark stops quickly. This means the contacts on AC switches are usually smaller than on DC switches and DC switches may use additional means to deal with the spark. This is not normally an issue with resistive loads like filament light bulbs but is a problem with inductive loads like motors and other things with coils in them. There MIGHT be a longer term problem with 12 volt LED bulbs that have built in electronics. Just to restate that usually a mains switch will work for DC lights but there is always a chance that it may fail before a DC switch.

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