Grey, red and blue Anderson plugs are often used to separate circuits in 4WD, caravan and canopy wiring. The important point is that colour is not just decoration: on genuine SB50 housings, the colour is tied to the mechanical keying of the connector. In most cases, plugs must be the same size, colour and keying to mate.
Colour does not create a universal wiring standard. A red plug is not automatically solar, and a blue plug is not automatically fridge power. The installer or vehicle owner decides what each circuit does. The safest approach is to match the connector exactly and label the circuit at both ends.
Quick answer: which colour should you choose?
| Situation | Best approach |
|---|---|
| Connecting to an existing plug | Match the exact plug family, size, colour and contact size. |
| Adding one general-purpose SB50 circuit | Grey is commonly used, but document the purpose of the circuit. |
| Keeping two or three circuits separate | Use different keyed colours and clear labels at both ends. |
| Replacing a damaged housing | Check the markings on the original connector; do not choose by appearance alone. |
Why SB50 colours do not always connect
Anderson Power Products describes SB50 housings as colour-coded and mechanically keyed. This helps prevent circuits with different purposes or voltages from being connected accidentally. The manufacturer also notes a specific exception: genuine black and grey SB50 housings share the same keying. Do not assume that exception applies to unbranded or Anderson-style copies.
The manufacturer's official SB50 housing page is the best reference for genuine housing keying and compatible contacts.
Grey Anderson plugs
Grey is the most common general-purpose colour in Australian 12V touring setups. It is frequently used for fridge power, solar input, battery charging and accessory feeds. Because it is common, the colour alone tells you very little about the circuit.
If you are matching a standard grey connection, see the grey genuine SB50 plug kit. Confirm the cable, contacts, fuse protection and expected current before installation.
Red Anderson plugs
Red is useful when you want a visibly separate circuit. A canopy builder might use grey for a general output and red for a second battery or dedicated accessory feed. That is a local convention, not a rule.
Use a red genuine SB50 plug kit only when the other connector is the matching red SB50 housing and the circuit has been verified.
Blue Anderson plugs
Blue provides another keyed option for separating a third circuit. For example, a builder may choose blue for portable solar, red for charging and grey for fridge power. Any layout can work if it is consistent, documented and labelled.
The blue SB50 plug kit is intended to mate with a matching blue SB50 connector.
Colour is not a substitute for a label
Vehicles change owners, accessories move and wiring gets modified. A label such as SOLAR IN, FRIDGE or DCDC INPUT is clearer than relying on colour memory. A fixed Anderson plug surface mount can keep the connection secure and make the circuit easier to identify.
Label both ends of the cable and record the following:
- Circuit purpose and direction of power flow
- System voltage
- Fuse or breaker rating
- Cable and contact size
- Connector family, size and colour
- Date of installation or last inspection
Do different Anderson plug sizes connect?
No. SB50, SB120, SB175 and SB350 housings are different sizes. Colour matching does not make different connector families compatible. Read our SB50 vs SB120 vs SB175 guide before choosing a mount or connector.
Before plugging in an unknown circuit
- Trace the cable and identify where it terminates.
- Confirm voltage and polarity with suitable test equipment.
- Check the fuse, cable and contact sizes.
- Confirm that the connector housing is an exact match.
- Ask a qualified auto electrician if the circuit is unclear.
Final word
Use Anderson plug colours to prevent mismating, not to guess what a circuit does. Match size and keying, add clear labels and verify the electrical design before connecting equipment.
Important safety information
Water protection: Dust covers, mounting gaskets and connector mounts discussed in this guide are not waterproof or watertight. Install them in a protected location away from direct spray, high-pressure water and immersion.
Electrical installation: All electrical wiring and installation must be carried out by a suitably qualified electrician or auto electrician, as appropriate. The installer must confirm cable sizing, terminations, fusing, circuit protection and suitability for the application.