---
product_id: 47624755
title: "30/40 AMP Relay Harness Spdt 12V Bosch Style - 4 Pack"
brand: "epauto"
price: "R552"
currency: ZAR
in_stock: true
category: "Ep Auto"
url: https://www.desertcart.co.za/products/47624755-30-40-amp-relay-harness-spdt-12v-bosch-style-4
store_origin: ZA
region: South Africa
---

# 40A max switching current Endures -40°C to +125°C 10ms ultra-fast operate time 30/40 AMP Relay Harness Spdt 12V Bosch Style - 4 Pack

**Brand:** epauto
**Price:** R552
**Availability:** ✅ In Stock

## Summary

> ⚡ Switch smarter, not harder — power your projects with speed and reliability!

## Quick Answers

- **What is this?** 30/40 AMP Relay Harness Spdt 12V Bosch Style - 4 Pack by epauto
- **How much does it cost?** R552 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.co.za](https://www.desertcart.co.za/products/47624755-30-40-amp-relay-harness-spdt-12v-bosch-style-4)

## Best For

- epauto enthusiasts

## Why This Product

- Trusted epauto brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Trusted Versatility:** Perfect for automotive accessories, robotics, and non-critical systems with a 4.7-star rating from 6,800+ users.
- • **Powerhouse Switching:** Handles up to 40 amps for heavy-duty automotive and DIY projects.
- • **Built to Brave Extremes:** Reliable performance from freezing cold to scorching heat (-40°C to 125°C).
- • **Lightning-Fast Response:** Operates in just 10 milliseconds to keep your circuits instantly responsive.
- • **Plug & Play Convenience:** Includes 4 relays with heavy-duty molded sockets and UL-listed pigtail leads for easy installation.

## Overview

This 4-pack of 30/40 AMP Bosch-style SPDT 12V relays offers robust 40A switching capacity, ultra-fast 10ms operation, and extreme temperature endurance (-40°C to 125°C). Each relay comes with a heavy-duty molded socket and UL-listed 6" pigtail wires for hassle-free installation. Ideal for automotive accessories, DIY electronics, and non-critical applications, these relays combine professional-grade specs with accessible pricing and a strong user approval rating.

## Description

Contact Capacity: Normal switching Capacity (res.load): - NO 40A 14VDC - NC 30A 14VDC Max. switching current: 40A Max. switching voltage: 30VDC Max. switching power: 560W Characteristic Data: Initial contact resistance (at 6VDC 1A): 50mΩ Max. Operate time (at nominal volt.): 10 msec. Max. Release time (at nominal volt.): 5 msec Max. Initial insulation resistance: 100MΩ Min. (DC500V) Initial dielectric strength: - Between open contacts: AC500V, 50/60 Hz 1Min. - Between coil and contact: AC500V, 50/60 Hz 1Min. Vibration resistance: - Functional: 10 ~ 55Hz at double amplitude of 1.5 mm - Destructive: 10 ~ 55Hz at double amplitude of 1.5 mm Shock resistance: - Functional: 20G Min. - Destructive: 100G Min. Endurance (operations): - Mechanical (at 7,200 ops./h): 10,000,000 - Electrical (at 600 ops./h): 100,000 Ambient Temperature: -40°C ~ +125°C (no condensation)

## Features

- 40A/30A high switching capability.
- Heavy-duty impact molded relay socket with 5 WIRES。White (common), Black (normally closed), and Yellow (normally open).
- Package Include: 4 relays + 4 relay sockets with wires.
- Safety UL Listed 6" wires with pigtail leads for the main contact.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B072QXDZRD |
| Best Sellers Rank | #35,055 in Automotive ( See Top 100 in Automotive ) #14 in Automotive Replacement Starter Relays |
| Brand | EPAuto |
| Brand Name | EPAuto |
| Coil Voltage | 12 Volts (DC) |
| Connector Type | Relay Socket |
| Contact Current Rating | 40 Amps |
| Contact Material | Silver |
| Contact Type | Spdt |
| Current Rating | 40 Amps |
| Customer Reviews | 4.7 out of 5 stars 6,846 Reviews |
| Manufacturer | EPAuto |
| Maximum Switching Current | 40 Amps |
| Minimum Switching Voltage | 1 Volts (DC) |
| Model | AE-001-2 |
| Mounting Type | Socket Mount |
| Operating Time | 0.01 Seconds |
| Operation Mode | Automatic |
| Part Number | AE-001-2 |
| Specification Met | UL |
| UPC | 707129801449 |
| Upper Temperature Rating | 125 Degrees Celsius |
| Wattage | 560 watts |

## Product Details

- **Connector Type:** Relay Socket
- **Contact Material:** Silver
- **Contact Type:** Spdt
- **Current Rating:** 40 Amps
- **Mounting Type:** Socket Mount

## Images

![30/40 AMP Relay Harness Spdt 12V Bosch Style - 4 Pack - Image 1](https://m.media-amazon.com/images/I/61dgzu6St0L.jpg)

## Available Options

This product comes in different **Size** options.

## Questions & Answers

**Q: Where does the red wire connects to?**
A: The red wire connects to pin 87a which remains in contact with the common (pin 30, blue) when the relay isn't energized.  this is known as the "Normally closed" (NC) circuit.  Don't use it unless you want the relay to power something off when the relay activates; i.e., for most operations you leave it disconnected.

**Q: What gauge are the leads that come off the relay?**
A: The wire on these harnesses are 16AWG and are too small for powering vehicles electric fan on radiator which pulls 15-30A per fan.
Use a 30A fuse right after the battery going to the 85/86 on relay, make sure the 30 & 87 on relay have 10ga OFC primary wire.
You need 10AWG guage for 7-16ft applications, it has to be OFC/Tinned Copper, make sure it's not CCA. GS Power brand on Amazon has OFC called 100% pure copper.
Pick up yellow(12-10 guage) heatshrink butt connectors(to connect the wires properly), yellow heatshrink female spade connectors(for relay post prongs) and some yellow heatshrink ring connectors in multipack of different ring diameters(for grounding the wire to Frame bolts)
Then get heatshrink tubing 1/4" should be fine if it's 3:1 or 4:1 Wirefy is a good brand. I get the spools instead of the precut packs.
Heatshrink connectors and durable heatshrink tubing is extreamly important for automotive purpose, the weather in vehicles can corrode it and cause melting or worse.

**Q: Will these work to shut off compressors for air ride suspension on a truck**
A: As long as the total amperage draw of the compressor and any other power consuming components of the air suspension system are less then the 40 amp relay, these should work fine.

**Q: Im more of an ac instead of dc guy but u can run 24v through ur no terminal just has to have 12v to bring in the coil on the relay correct?**
A: You can apply 12VDC to the coil (usually, that means 10 -15VDC) to close the contacts of the Normally Open terminals.  When the Normally Open terminals are closed, the Normally Closed terminals are open.Once the terminals are closed, they can handle 30 amps DC.There isn't a specification for the voltage that the N/O and N/C terminals can handle... but I'm certain that they can handle 24 volts.Just don't put more than 14.4VDC across the coil.

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*Product available on Desertcart South Africa*
*Store origin: ZA*
*Last updated: 2026-06-25*