Automotive Relay Panel SPST – All N.O. Contacts

(13 customer reviews)

$125.00$245.00 (USD)

Get ultimate control of your high-current devices. MGI’s most flexible modular relay panel is designed for easy installation. Can handle up to 20A resistive loads @ 12vDC, and up to 16A electric motor loads (fans and pumps).

  • 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
    Reset options
    Choose your own fuse and feeder cable sizes.

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

    All relay panels are factory wired with #14 AWG. Click the checkbox below if you wish to have one or more relays installed with #12 AWG wire instead.

    Dust-tight and weatherproof IP66 rating. See our RCP enclosure page for more details.

find individual units sold on Amazon


Automotive Relay Panels by MGI SpeedWare
use our interactive builder to customize your multi-relay control panel

mgi speedware relay panel kits
automotive relay panel

Pre-Wired Relay Box with Built-In Fuses

An MGI relay box can control high-current car accessories that regular switches can’t handle. Have electric motors, spotlights, or high-current resistive loads? A relay box will do the trick. Comes with fused relays, a main fuse, and main feeder conductor.

  • Can handle up to 20A resistive loads, and up to 16A electric motor loads (fans and pumps).
  • Lightweight and compact aluminum construction
  • No messy wiring — the SPST relays are pre-wired and ready to go
  • Every individual relay allows for negative switching
  • Proudly designed and assembled in North America
  • #6 bolt-size screw terminals are labeled for easy wiring


Innovative relays with built-in fuses greatly reduces the amount of wiring needed. SPST relays are rated 40A at 12vDC, with smart LED fuses that glow when blown. What’s more, each relay and fuse can be easily replaced if needed.

automotive relay panel with terminal strips


High-quality barrier screw terminals makes wiring quick and easy, especially with fork / spade connectors. Each screw is clearly numbered – simply use the included wiring diagram to make your connections.

automotive relay panel rear


MGI SpeedWare relay boxes are designed to reduce custom wiring as much as possible – that’s why our boxes are pre-wired and ready to go. All you need to do is connect a power source, switches and loads to the appropriate screw terminal.

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.

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.

13 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)

  6. MARCUS WATSON (verified owner)

  7. Joseph S. (verified owner)

    Just what I need to run my fuel pump and fan on my 1952 Ford F1

    Image #1 from Joseph S.
  8. Dustin (verified owner)

    The relay box was great but the weatherproof box that was supposed to come with it never came. The fuses included don’t stay in well.

  9. William Peters (verified owner)

    Made the mistake of going with a plastic relay kit first, than saw this. Well made, durable, the exact thing you would do if you built it yourself. Thought out and built with quality. If you are doing a Sniper (or similar)EFI, use this, one for the fan and the other two for the ignition hot wires.

  10. Brent H. (verified owner)

    Working well so far.
    1954 chevy truck resto..

    Image #1 from Brent H.
  11. Brian Wagler (verified owner)

    Had no idea any thing like this existed, effortless hookup and very tidy.
    I rewired a Star insulation blower powered by a Honda GX390 (Also a Canadian machine 😊). This particular piece of equipment is a heavy used item and has to be dependable as well as user friendly. MGI Speedware has both covered very well.
    Would recommend this as a necessity in any industrial wiring applications.
    Also customer service is very friendly and helpful👍🏽.

  12. Rick Farber (verified owner)

    The item worked exactly as expected

  13. Earl (verified owner)

    I will be ordering again loved it

    Image #1 from Earl
    Image #2 from Earl
Add a review

Your email address will not be published. Required fields are marked *

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.