Relays and Solenoids

Relays are used anytime you need to switch a high-current accessory via a low-current output. For example, you’d like to turn on an electric fan via one of the programmable outputs of your aftermarket EFI system. No problem. Solenoids are simply SPST relays that can switch very high current loads. They’re perfect for auxiliary battery installations, remote battery disconnects, or switching very high current accessories.

Need to brush up on your skills with relays? No problem. Chapter 4 of Automotive Wiring and Electrical Systems covers relays–and how to put them to work–in-depth.

The Basics

Hella 40-Amp Relays
Close-up of Hella Waterproof 40-Amp Relays
  • SPST – Single Pole Single Throw
  • SPDT – Single Pole Double Throw
  • C – Common
  • N.O. – Normally Open
  • N.C. – Normally Closed

In the photo is a pair of Hella waterproof relays installed as they come with our Headlight Relay Kits, clean and serviceable!

Over the years, we’ve used nearly every brand of relay and solenoid you’ve heard of (and some that you haven’t). Our selection is based on the ones that we’ve experienced the best service from.

Relays & Relay / Socket Kits

We recommend the MSD Pro Crimp Tool (part # MSD35051) and MSD Open Barrel Terminal Crimp Die (part # MSD3506) for assembling any of our relay kits. Both are available on our Tools Page

Pre-Wired Relay Sockets

Most pre-wired relay sockets simply aren’t worth buying because the terminals are low quality and the gauge of wire undersized. For that reason, we hand build our own relay sockets with tin plated OEM quality terminals, 16 AWG GPT for the coil connections, and 10 AWG TXL for the switch connections. In addition, we crimp and solder the 10 AWG switch wires to ensure low resistance and excellent reliability.

Relay Socket Terminals

Spare terminals for all of the relay / socket kits that we offer.

ISO 280 Series Relays

Perfect for our Waterproof Power Distribution Centers!

Solenoids

Available up to 500A for the highest current switching needs!