2-pole MCBs disconnect both line and neutral during a fault, making them essential on certain circuits where full isolation is required for safety and compliance. They’re commonly used on outdoor supplies, plant equipment, TT systems and any circuit where a single-pole device isn’t enough.
Quick Answer: A 2-pole MCB breaks both live and neutral, providing full isolation under fault conditions. You need one when supplying outdoor equipment, machinery, TT installations, or any circuit where neutral disconnection is required under BS 7671. They also prevent backfeed risks on shared neutrals.
See the full range: 2-Pole MCBs
Jump to:
What a 2-Pole MCB Actually Does
Unlike a single-pole MCB, which breaks only the line conductor, a 2-pole MCB mechanically links both poles - ensuring line and neutral disconnect together under fault or manual operation.
This is critical for:
- Full isolation during faults
- Neutral disconnection on TT systems or shared neutrals
- Preventing backfeed from connected loads
- Safe maintenance on outdoor or exposed equipment
When You Need a 2-Pole MCB
2-pole MCBs are the correct choice whenever BS 7671 requires full disconnection - or where neutral continuity can create a hazard.
Use a 2-pole MCB for:
- Outdoor and exposed circuits (sheds, garages, gardens)
- TT installations where neutral must disconnect
- Machinery and plant equipment requiring full isolation
- Heat pumps, condensers and AC units on external walls
- Circuits with shared neutrals or multi-core feeds
- Temporary supplies and portable equipment
- Caravans, outbuildings and marinas
In these cases, a single-pole MCB does not offer adequate safety or compliance.
When Not to Use a 2-Pole MCB
They are not replacements for switching or isolation devices unless specifically designed for that purpose. They also aren’t required on standard domestic lighting or socket circuits.
Avoid 2-pole MCBs for:
- Standard 230V final circuits (ring, radial, lighting)
- Applications needing a dedicated isolator - use a switch-disconnector instead
- Three-phase circuits - use 3-pole or 4-pole devices
- Circuits where neutral switching is not beneficial
Installer-Favourite 2-Pole MCBs
These units are commonly used for outdoor supplies, plant equipment, TT systems and any circuit requiring neutral disconnection.
- 16A 2-Pole 10kA MCB – B Curve
- 50A 2-Pole 10kA MCB – C Curve
- 40A 2-Pole 10kA MCB – C Curve
- 40A 2-Pole 10kA MCB – B Curve
- 32A 2-Pole 10kA MCB – C Curve
- 32A 2-Pole 10kA MCB – B Curve
- 20A 2-Pole 10kA MCB – C Curve
- 16A 2-Pole 10kA MCB – C Curve
- 10A 2-Pole 10kA MCB – C Curve
Browse the full category: 2-Pole MCBs
FAQs
Installers often need clear guidance on when full disconnection is required. These quick FAQs cover the main use cases.
Do 2-pole MCBs provide isolation?
They provide full disconnection of line and neutral, but they are not a substitute for a dedicated isolator unless rated for that purpose.
Are 2-pole MCBs required on TT systems?
Yes - BS 7671 generally requires neutral disconnection on TT installations.
Should outdoor circuits use a 2-pole MCB?
In most cases, yes. Outdoor or exposed equipment benefits from full disconnection for safety and maintenance.
Do 2-pole MCBs work with RCDs and RCBOs?
Yes - they can be used upstream or in combination depending on the design of the circuit and required protection.
👉 Need full line + neutral disconnection for safe isolation? Shop all 2-Pole MCBs