Automotive Relay Panel SPST – All N.O. Contacts

(5 customer reviews)

$75.00$195.00 (USD)

Get ultimate control of your high-current devices. MGI’s most flexible modular relay panel is designed for easy installation.

  • Pre-wired with 3, 4, 6, or 8 SPST relays rated 40A
  • Built-in smart LED fuses that glow when blown
  • Comes with main feeder and main fuse
  • Easy to wire — Standard normally open (N.O.) operation
  • Each individual relay can be wired for either positive or negative switching
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    Reset options

    Protect your relays from flyback voltage when the power supply is suddenly disconnected. See What is a Flyback Diode? for more info.

    Choose your own fuse and feeder cable sizes. You can choose individual fuse sizes, between 5 - 40A. If the checkbox below is not selected, MGI will supply fuses and main feeder as follow:


    Our load size calculator automatically selects a larger main feeder conductor when necessary.


High-Power Automotive Control
for when regular switches won’t work


Your high-power solution for when regular switches can’t handle high-current loads. Adding relays can become a complicated and messy project ⁠— our fused relay boxes provide centralized control and protection with minimal wiring involved. Ideal for all automotive devices such as spotlights, motors, pumps, and fans.


Wiring is made easy. Each automotive relay box comes with a red main feeder cable and labeled screw terminals. Use the Installation Manual and wiring diagrams to help connect your power source, switches, and loads. It’s that easy.


Quality is Guaranteed. Every automotive relay box is tested, with relays rated 40A at 12 volts to ensure optimal reliability come race time. What’s more, our relay boxes are built with GXL high temperature wire, and with no-nonsense screw terminal strips for reliable input and output wiring.

Modular Relay Panel Features
use our interactive builder to customize your multi-relay control module

Modular Relay Panel Wiring Diagrams
how to install 3, 4, 6, and 8 relay modules


Battery Power

relay box power

Connect the red main feeder conductor to the car starter’s battery power terminal. Then, install the supplied main fuse and holder in the main feeder conductor between the starter and the power stud found inside the panel.


Switches & Grounds

relay switches

Install a ground wire between the relay panel and the auto chassis. Then, connect the control circuit terminal to your switch inputs, with switch outputs connected to the appropriate screw terminals.


Outgoing loads

relay box wiring

Connect your loads to the appropriate screw terminals. Ground your loads. See the 3, 4, 6, and 8 relay module diagrams above.

what comes with every SPST automotive relay panel kit

  • Aluminum frame module and your choice of 3, 4, 6, or 8 built-in relays
    • 40 Amp SPST relays
    • Integrated fuses
  • Integrated LED blade fuses (+ spares)
    • ATC / ATO style blade fuse with LED light that glows when blown
    • Available in sizes 5 to 40A
  • 5A LED control circuit fuse (+ spare)
  • Main fuse & fuse holder
    • Mini ANL bolt-down fuse
    • Available in sizes up to 150A
  • 5′ main feeder conductor
    • Available in sizes up to #2 AWG

Answers to Popular questions

Why buy a fuse & relay panel?

When rebuilding, restoring, or refurbishing your vehicle, you’re bound to need electric pumps, fans, spotlights and more. These high-current devices will damage regular ignition key switches or low-current switch panels — however, an electromagnetic switching relay panel will give you the safe and reliable control you need.

Can this relay box operate “normally closed” devices?

No. Our SPST relay boxes are designed for standard normally open (N.O.) loads only. However, our specialty SPDT Bosch style relay boxes can power devices that are normally closed.

some popular relay panel projects

Negative Switching

Some devices are designed specifically for negative ground switching. With our SPST relay panels, every individual relay allows for negative switching. Simply connect your switch between the appropriate ground terminal and chassis. Note: switches with LEDs will not function properly with negative switching.


Relay Box Specs
without feeder, fuses, and main fuse holder

Physical Dimensions (L x W x H)
4.5" x 3.50" x 3.25"
14 oz

4 Relay Box — RCP3-GEN3

Physical Dimensions (L x W x H)
5.625" x 3.50" x 3.25"
18 oz

4 Relay Box — RCP4-GEN3

Physical Dimensions (L x W x H)
6.25" x 4.5" x 3.25"
28 oz

6 Relay Box — RCP6-GEN3

Physical Dimensions (L x W x H)
6.625" x 5.625" x 3.25"
36 oz

8 Relay Box — RCP8-GEN3

All dimensions and weights are supplied as general information only and are not certified.

5 reviews for Automotive Relay Panel SPST – All N.O. Contacts

  1. Keith Conner (store manager)

    Made my life alot easier wiring spotlights on my truck. Saved me the hassle of wiring relays all over the place.

  2. paisleyrowley (store manager)

    works like a charm. glad its made of metal.

  3. Kelsi (store manager)

    Great price and comes with everything you need. This kit came with everything I needed and was easy to install.

  4. carlton.calhoun122 (store manager)

    thumbs up

  5. Don Knight (verified owner)

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Before finalizing your purchase

It is important to familiarize yourself with the MGI panel Installation Manual. Not only does this help you to select the appropriate options for your race panel, it will enable you to tackle any troubleshooting issues with confidence.