MCB’s
TP&N board MCBs are miniature circuit breakers that protect cables in three phase distribution boards against overload and short circuit. The range covers Garo single pole MCBs in B and C characteristics, Garo triple pole C curve breakers from 6A to 63A, a Garo 3 pole B characteristic MCB and a Live Electrical 32A single pole 10kA breaker.
Trade prices are available to account holders, and stocked breakers ordered by 5pm on any weekday are delivered next working day across Northern Ireland and the Republic.
Choosing MCBs for three phase boards
A TP&N board usually carries a mix of triple pole MCBs for three phase equipment and single pole MCBs for lighting and small power circuits taken from individual phases.
Single pole or triple pole?
- Single pole - protects one line conductor for single-phase circuits, such as lighting, sockets and heaters.
- Triple pole - protects all three lines with a common trip, so a fault on one phase disconnects all three. Essential for three phase motors, sub-boards and plant.
Choosing the curve
B characteristic breakers suit resistive and general loads with low inrush. C characteristic breakers, such as the Garo 3 pole C range, tolerate the higher inrush of motors, transformers and large lighting installations without nuisance tripping. The designer should confirm that the chosen curve still disconnects within the required time for the circuit's earth fault loop impedance.
Breaking capacity and rating
Check that the kA rating (6kA or 10kA in our range) is equal to or greater than the prospective fault current at the board, which can be higher in commercial premises close to the supply transformer. Size the current rating to protect the cable while carrying the design load.
Installation tips
- Use breakers compatible with your TP&N board so they seat on the busbar correctly.
- Balance single pole circuits across the three phases.
- Add RCBOs where single-phase circuits need earth leakage protection.
- Motor circuits often need an overload relay and contactor, available in control and automation.
Always work to current wiring regulations and the manufacturer's instructions.
Meteor Electrical is a family-run wholesaler with 5,000+ products in stock and more than 40 years of trade experience. Delivery is free over £30 / €35 ex VAT, and credit accounts are available subject to approval.
FAQ's
- What are MCBs?
- What do MCBS protect against?
- What can cause MCBs to trip?
- Where are B curve MCBS used?
- Where are C curve MCBS used?
- When should I use a triple pole MCB?
- Can three single pole MCBs be used instead of a triple pole MCB?
- Which MCB should I use for a three phase motor?