rusty
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| posted on 3/4/06 at 02:32 PM |
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Do I need a relay for brake lights
I have a lucas in line brake light switch can I wire the lights through this or shall I fit a relay I only ask this because there is no rating on the
switch.
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David Jenkins
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| posted on 3/4/06 at 02:35 PM |
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Should be OK without a relay - it's not very high current (50W - approx 4 Amps) and non-inductive (no sparking).
David
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Dave J
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| posted on 3/4/06 at 03:08 PM |
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No you shouldn't need a relay. My brake light switch is similar to yours. No relays required, works fine.
Cheers,
Dave
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Hellfire
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| posted on 3/4/06 at 03:26 PM |
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No
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wilkingj
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| posted on 3/4/06 at 08:28 PM |
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Definately no relay required for 2 x 21watt brake lights, thats 42 watts divide by 12v, and is about 3.5 Amps.
I would have said they were an inductive load. ie they are a coil of wire! (Bulb filament). Still it will make no difference.
The inductive part has nothing to do with sparking. Its all about the reversed currents that are produced when you switch off the supply to an
inductive load, its generates a Back EMF. (reverse current / voltage, as the magnetic field which was produced when the device was working / powered
up. When the power is removed the collapsing magnetic field induces a voltage / current in the wire / coil, in the reverse direction, this can damage
sensative electronic components
Non sparking devices are usually called "intrinsically safe"
I have fitted enough of those devices in Fuel Dumps and Petro Chemical Installations in years gone by.
They definately are not a capacitive load either
All good fun eh!..
My build is coming along nicely... hope to have it done for this summer... original date was Last Summer
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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k33ts
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| posted on 3/4/06 at 09:14 PM |
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in a simpler term, no
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David Jenkins
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| posted on 4/4/06 at 07:33 AM |
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quote:
Originally posted by wilkingj
I would have said they were an inductive load. ie they are a coil of wire! (Bulb filament). Still it will make no difference.
The inductive part has nothing to do with sparking.
I know!
I was just trying to keep my answer simple, without quoting back EMF & other such techie talk. In other words, if it's got big coils at
significant current (e.g. motors) then a relay is a very good idea. Otherwise, no.
David
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