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Author: Subject: switch ratings....
Viper

posted on 27/5/06 at 01:48 PM Reply With Quote
switch ratings....

can any one help????
what amperage does a fog light switch need to be able to handle? and what if it went through a relay?

also what amperage switch for ignition "on" (so to speak) if switched through a relay???

any ideas chaps?
cheers......






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Howlor

posted on 27/5/06 at 02:16 PM Reply With Quote
Well i think a fog light is about 21W so if you are going to fit two then 42W, P=IV so 42/12=3.5A.

With a relay it can be very little.

Steve

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Viper

posted on 27/5/06 at 02:27 PM Reply With Quote
I am only itting one fog light, those numbers you posted look a lot like math to me and my little brain don't do math.....

so only one fog light (21w) the switch would need to have a minimum rating of?






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Howlor

posted on 27/5/06 at 02:54 PM Reply With Quote
It then would be 21W/12V = 1.75A. I am uncertain for an ignition switch but I would reckon on about 25A.

hope that helps,
Steve

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ady8077

posted on 27/5/06 at 04:36 PM Reply With Quote
Hi

If your looking for switches from maplins/ rs etc, make sure the amp rating is for a DC voltage

Adrian

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Viper

posted on 27/5/06 at 04:48 PM Reply With Quote
all a bit to complicated for me....
so is there any way of working out what i would need if it is advertised as a AC switch?






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BKLOCO

posted on 27/5/06 at 06:27 PM Reply With Quote
quote:
Originally posted by Viper
all a bit to complicated for me....
so is there any way of working out what i would need if it is advertised as a AC switch?


No not really.
The problem is that DC draws an arc as the contacts break whereas AC doesn't.
Therefore different contact material tends to be used for the two switches.
As a general rule of thumb however if the ac rating is in the order of 4 to 6 times what you intend to switch dc you should be ok.

[Edited on 27-5-06 by BKLOCO]





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