do i need a relay?

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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=28758
Printed Date: July 18, 2025 at 6:03 AM

Topic: do i need a relay?

Posted By: superxox
Subject: do i need a relay?
Date Posted: March 21, 2004 at 12:56 AM

I am about to install a pair of H3 fog lights, 55W on each. I bought a switch from RadioShack, click here, which I want to use for the fog lights. This switch says it's rated 30A. My question is, since this switch is able to handle 30A, is this means I can eliminate to use a relay? and connect the power to the fog lights thru this switch?

Thanks for any help!

Replies:

Posted By: Cozz
Date Posted: March 21, 2004 at 9:57 AM

Well, yes you don't need a relay but I always hated having high current wires under the dash. I like to send a low signal to the engine bay to turn on the the relay from the battery. But whatever the choice, make it fused.

Posted By: Teken
Date Posted: March 21, 2004 at 5:24 PM

I would reiterate what Cozz has said as well. The main reasons for using the relay is to safely switch on-off a high current device with a low voltage / current device or switch.

The relay will also isolate the circuit. Having a high current power wire running through the interior vehicle requires more care and safety also.

Meaning you will have to ensure proper clearence, and grommet use, or any other tubing to provide that measure of safety.

Normally people use the ground to switch a device on-off
to initiate the turn on sequence.

Regards

EVIL Teken . . .