Roots 12V 30 Amp Relay – Heavy Duty Automotive Relay for Bikes & Cars | 4 Pin Micro Relay

Q: How does a 30 amp relay work?

A 30 amp relay works as an electrically operated switch. When a small control current (typically 200–300mA) energises the relay coil through pins 85 and 86, it creates a magnetic field that pulls the internal armature and closes the main contact between pins 30 and 87. This allows up to 30A of load current to flow — powering accessories like fog lights, auxiliary lamps, or horns — without running that high current through your handlebar switch or ECU. When the control signal is removed, the spring resets the contact and the circuit opens, protecting your wiring and switches from heat damage.

Q: What is a micro relay?

A micro relay is a compact, space-saving version of a standard automotive relay — smaller footprint, same switching capability. The Roots RMCR4A is a 4 pin micro relay that fits tight spaces in motorcycle headlight assemblies, under-seat electrical boxes, and car fuse boxes where a full-size relay won't fit. Despite its small size, it handles the same 30A load as a standard relay, making it ideal for motorcycle auxiliary light relay setups and compact car builds.

Q: What is the cost of a 30 amp relay?

A quality 30 amp automotive relay in India typically costs between ₹80–₹350 depending on brand and build quality. The Roots 12V 30A relay (RMCR4A) is available at ₹299 for the relay only, or ₹499 as a combo with the matching coupler — offering branded reliability at a competitive price point. For critical circuits like fog lights, horns, or headlight upgrades, investing in a quality relay prevents wiring damage and repeated replacements.

Q: Which pin is which on a 4 pin relay?

On a standard 4 pin automotive relay: Pin 30 is the common terminal (connects to your power source/battery); Pin 87 is the normally open (NO) output — this is where your accessory (fog light, horn, etc.) connects; Pin 86 is the coil positive — connects to your switch or trigger wire; Pin 85 is the coil negative — connects to ground. When 12V is applied to pin 86 and pin 85 is grounded, the relay closes and power flows from pin 30 to pin 87.

Q: Do I need a relay for fog lights on my bike?

Yes — for any auxiliary fog light or LED driving light drawing more than 5–10W, a relay is strongly recommended. Running high-current loads directly through your handlebar switch causes switch contacts to burn out over time and can damage your bike's wiring harness. A 30 amp relay for fog lights routes the heavy current directly from the battery to the lights, with your switch only triggering the low-current relay coil. This protects your OEM wiring, prevents voltage drop, and ensures your lights run at full brightness.

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⚡ Roots 12V 30A Relay – Heavy Duty Automotive Relay for Bikes & Cars

Trusted Switching Power for Every Auxiliary Circuit

The Roots 12V 30 Amp relay (Model RMCR4A) is a compact, 4 pin micro relay built for reliable switching of fog lights, auxiliary lamps, horns, cooling fans, and fuel pump circuits on motorcycles, bikes, cars, and SUVs. Engineered to automotive-grade standards, this heavy duty automotive relay handles demanding Indian road conditions — from peak summer heat to monsoon moisture. Whether you're a DIY enthusiast or a professional installer, the Roots relay delivers consistent, long-life performance in every circuit.

Key Features & Benefits

✅ 30 Amp Current Rating
Handles high-draw accessories — fog light relay, auxiliary lamps, horns, and cooling fans without voltage drop or overheating.
✅ 12V DC Universal Operation
Standard 12v relay for bike and car use — compatible with all 12V automotive electrical systems.
✅ 4 Pin Micro Configuration (SPDT)
Compact micro relay footprint with pins 30, 87, 86, 85 — fits standard relay sockets and couplers for plug-and-play installation.
✅ Heavy-Duty Construction
Durable housing with reliable silver-alloy contact points for long service life — built for the automotive relay demands of Indian roads and international touring.
✅ Wide Temperature Range
Operates from -40°C to +85°C — heat resistant and moisture tolerant for engine bay and underbody mounting.
✅ Universal Vehicle Compatibility
Works on motorcycles, scooters, bikes, cars, jeeps, SUVs, and commercial vehicles — a true universal relay for vehicles.

🔧 Why Choose the Roots 12V 30A Relay?

Roots is a trusted name in Indian automotive electrical components. This 30 amp relay is workshop-tested for consistent switching performance — no chatter, no premature contact wear. Unlike generic relays, the RMCR4A uses a robust coil design that draws minimal current from your control circuit while switching up to 30A on the load side. Ideal as a headlight relay upgrade, horn relay, or auxiliary light relay for motorcycle and car builds.

Pair it with our Heavy Duty 4 Pin Micro Relay Coupler for a weatherproof, solder-free installation — no crimping required. A complete relay wiring solution for bikes and cars.

Suitable For

🏍️ Motorcycles & Bikes (all makes and models)
🛵 Scooters & Mopeds
🚗 Cars, Sedans & Hatchbacks
🚙 SUVs, Jeeps & MUVs
🚐 Commercial Vehicles & Vans
🔧 DIY Electrical Builds & Professional Installations

Specifications

Brand: Roots
Model: RMCR4A
Voltage: 12V DC
Current Rating: 30 Amps
Pin Configuration: 4 Pin Micro Relay (30, 87, 86, 85)
Contact Type: SPDT (Single Pole Double Throw)
Operating Temperature: -40°C to +85°C

Package Includes

📦 1x Roots 12V 30A Relay (Model RMCR4A)
📋 Pin layout reference on relay body

❓ Frequently Asked Questions

How does a 30 amp relay work?

A 30 amp relay works as an electrically operated switch. When a small control current (typically 200–300mA) energises the relay coil through pins 85 and 86, it creates a magnetic field that pulls the internal armature and closes the main contact between pins 30 and 87. This allows up to 30A of load current to flow — powering accessories like fog lights, auxiliary lamps, or horns — without running that high current through your handlebar switch or ECU. When the control signal is removed, the spring resets the contact and the circuit opens. This protects your wiring and switches from heat damage.

What is a micro relay?

A micro relay is a compact, space-saving version of a standard automotive relay — smaller footprint, same switching capability. The Roots RMCR4A is a 4 pin micro relay that fits tight spaces in motorcycle headlight assemblies, under-seat electrical boxes, and car fuse boxes where a full-size relay won't fit. Despite its small size, it handles the same 30A load as a standard relay, making it ideal for motorcycle auxiliary light relay setups and compact car builds. Pair it with a matching 4 pin micro relay coupler for a clean, plug-and-play installation.

What is the cost of a 30 amp relay?

A quality 30 amp automotive relay in India typically costs between ₹80–₹350 depending on brand and build quality. Generic unbranded relays are cheaper but prone to contact failure and voltage drop under sustained load. The Roots 12V 30A relay (RMCR4A) is available here at ₹299 for the relay only, or ₹499 as a combo with the matching coupler — offering branded reliability at a competitive price point. For critical circuits like fog lights, horns, or headlight upgrades, investing in a quality relay prevents wiring damage and repeated replacements.

What are the 4 types of relays?

The four main types of relays used in automotive applications are: 1) SPST (Single Pole Single Throw) — simplest type, one input and one output, either open or closed; 2) SPDT (Single Pole Double Throw) — like the Roots RMCR4A, it can switch between two outputs (pins 87 and 87a), making it the most versatile 4 pin relay for bikes and cars; 3) DPST (Double Pole Single Throw) — controls two separate circuits simultaneously with one coil; 4) DPDT (Double Pole Double Throw) — two independent SPDT switches in one relay body, used in complex switching applications. For most motorcycle and car auxiliary wiring, an SPDT micro relay like the Roots 12V 30A is the go-to choice.

Which pin is which on a 4 pin relay?

On a standard 4 pin automotive relay: Pin 30 is the common terminal (connects to your power source/battery); Pin 87 is the normally open (NO) output — this is where your accessory (fog light, horn, etc.) connects; Pin 86 is the coil positive — connects to your switch or trigger wire; Pin 85 is the coil negative — connects to ground. When 12V is applied to pin 86 and pin 85 is grounded, the relay closes and power flows from pin 30 to pin 87. The pin numbers are printed on the Roots RMCR4A relay body for easy reference.

Do I need a relay for fog lights on my bike?

Yes — for any auxiliary fog light or LED driving light drawing more than 5–10W, a relay is strongly recommended. Running high-current loads directly through your handlebar switch causes switch contacts to burn out over time and can damage your bike's wiring harness. A 30 amp relay for fog lights routes the heavy current directly from the battery to the lights, with your switch only triggering the low-current relay coil. This protects your OEM wiring, prevents voltage drop, and ensures your lights run at full brightness. The Roots 12V 30A relay is purpose-built for this application.

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