Automotive Circuit Protection

12V Pre-Wired Fuse Relay Box – 4 Relays, 6 Fuses

This pre-wired fuse relay box combines four 12V 40A automotive relays with six ATO/ATC blade fuse positions in one organized electrical control assembly. The pre-wired harness simplifies integration into vehicle accessory circuits, while the four-pin normally open relays provide switching control for multiple electrical loads.

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Built for Reliable Electrical Protection

Product Overview

Pre-Wired Fuse Relay Box for 12V Automotive Circuits

A pre-wired fuse relay box combines relay switching and fuse protection within one organized electrical control assembly. This configuration includes four 12V 40A automotive relays, six standard ATO/ATC blade fuse positions and a pre-wired wiring harness for integration into vehicle and equipment electrical systems.

The four-pin relays use terminals 30, 85, 86 and 87 in a normally open switching configuration. This allows a low-current control circuit to switch a higher-current accessory circuit while the blade fuse positions provide separate overcurrent protection points within the electrical system.

pre-wired automotive relay fuse box detail showing four 12V 40A relays and six blade fuse positions

Key Features

  • Four automotive relay positions
  • Four 12V 40A relays included
  • 4-pin normally open relay configuration
  • Relay terminals: 30, 85, 86 and 87
  • Six ATO/ATC standard blade fuse positions
  • Pre-wired wiring harness
  • Integrated fuse and relay arrangement
  • Flame-retardant nylon base
  • Plastic protective cover
  • Designed for organized 12V accessory circuit control

Specifications

Item Specification
Model CZY-RB01
Product Type Pre-Wired Fuse Relay Box
Operating Voltage 12V DC
Number of Relays 4
Relay Type 4-Pin Automotive Relay
Relay Rating 12V DC / 40A
Relay Contact Normally Open (NO)
Relay Terminals 30 / 85 / 86 / 87
Number of Fuse Positions 6
Compatible Fuse Type ATO/ATC Standard Blade Fuse
Wiring Pre-Wired Harness
Base Material Flame-Retardant Nylon
Cover Material Plastic

Applications

A pre-wired fuse relay box is useful in 12V electrical systems where several accessory circuits require both switching control and fuse protection.

  • Automotive accessory wiring
  • Auxiliary lighting circuits
  • Cooling fan control
  • Horn circuits
  • Pump control circuits
  • Vehicle modification projects
  • Truck and utility vehicle electrical systems
  • Custom 12V wiring assemblies

How the Fuse and Relay Box Works

The relay and fuse functions perform different roles within the electrical system. The fuse positions provide overcurrent protection, while the relays allow relatively low-current control signals to switch higher-current electrical loads.

This pre-wired fuse relay box groups both functions into one assembly, helping reduce scattered relay sockets, inline fuse holders and loose wiring within a multi-accessory installation.

4-Pin Relay Terminal Functions

The supplied relays use the common automotive four-pin arrangement:

  • Pin 30 — common power contact
  • Pin 87 — normally open switched output
  • Pin 85 — relay coil terminal
  • Pin 86 — relay coil terminal

When the relay coil is energized through terminals 85 and 86, the normally open contact closes between terminals 30 and 87, allowing power to flow to the controlled load.

Why Use a Pre-Wired Relay Box?

Installing multiple individual relays, sockets and fuse holders separately can create a larger number of loose connections and make the wiring system more difficult to organize.

A pre-wired fuse relay box centralizes four relay circuits and six fuse positions while providing an integrated wiring harness. This can simplify electrical assembly and make future circuit inspection and servicing more organized.

Fuse Selection Notes

The fuse rating should be selected according to the connected load, conductor size and circuit protection requirements. The presence of multiple fuse positions does not mean that every circuit should use the same fuse rating.

Fuse color alone should not be used to determine the required current rating. Always confirm the actual fuse marking and the electrical requirements of the protected circuit.

Relay Selection Notes

The supplied relays are rated at 12V DC and 40A. The relay rating describes the switching capability of the relay and should not be treated as the required operating current of every connected accessory.

The electrical load, conductor size, fuse rating and relay capacity should be evaluated together when designing the complete circuit.

FAQ

What type of relay is used in this pre-wired fuse relay box?

The assembly uses four 12V 40A four-pin automotive relays with terminals 30, 85, 86 and 87 in a normally open configuration.

What type of fuse does the relay box use?

The fuse positions are designed for standard ATO/ATC blade fuses.

Does a 40A relay mean every circuit must draw 40A?

No. The 40A value is the relay’s current rating. The actual circuit current depends on the connected electrical load, wiring and fuse selection.

What is the benefit of a pre-wired relay box?

A pre-wired design combines relay sockets, fuse positions and wiring into one organized assembly, reducing the amount of separate circuit hardware that must be installed individually.

Can the fuse rating be selected according to each accessory?

Yes. Fuse selection should be based on the requirements of each protected branch circuit, including the connected load and conductor size.

OEM / ODM Support

Cozy Electronics provides OEM and ODM support for relay boxes, automotive circuit protection products, wiring harnesses and customized electrical assemblies. Buyers can provide circuit requirements, relay configuration, fuse requirements, connector information and wiring specifications for project evaluation.

Contact Cozy Electronics for relay box specifications, custom wiring requirements and OEM/ODM project inquiries.

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