The Circuit Breaker has a very different role in life than the Trip Switch. When you have too many appliances working at the same time, or you badly damage an electric cable, it's the MCB that trips. This innocent looking device is usually the culprit in cases of cables melting and fuseboards catching fire. Always remember the Golden Rule; never replace a CB with a higher rated one unless the cable can handle it. Each electrical circuit must have the correct rated MCB protecting the cable which it supplies in accordance with the maximum current carrying capacity of the cable. A Circuit Breaker rated higher than the cable it protects will cause the cable to overheat before it can trip, causing damage to the installation and a risk of fire. To check the condition of the Circuit Breakers in your Consumer Unit, look for signs of burning (eg discolouring or browning). Look for signs that the CBs have been changed since the original installation (eg there maybe a mixture of different makes). Remember, a CB that has been changed and re-fitted with a higher rating than the cable it protects is a fire hazard, that's the same as placing a nail in a fuse holder. Occasionally CBs stick, it fails to trip but the supply still goes off, a little wiggle now and then will prevent that. Circuit Breakers are practically 99% 'fail safe'. Correctly fitted, they either 'make' or 'break' and require no maintenance. Use this table as a guide for checking the correct size Circuit Breakers are fitted in your Consumer Unit;
  • 10 Amp
  • 16 Amp
  • 20 Amp
  • 25 Amp
  • 1.5 mm²
  • 2.5 mm²
  • 4.0 mm²
  • 6.0 mm²
  • lighting, alarms
  • socket outlets, a/c units
  • utilities, jacuzzi
  • cooker, swimming pool
In Spain, all the MCBs used to protect individual single phase circuits should be 2-Pole, ie the device switches both the live and the neutral. Sparks Electrical Services can upgrade and rewire existing Consumer Units and Distribution Boards, together with all the internal Circuit Breakers and Trip Switches.
    Circuit breakers   MCB's