Formerly imperial ratings were used for fuses and circuit breakers, but the international Renard ratings have now been added and will supersede them.
Fuse manufacturers are still using the imperial sizes while circuit breaker manufacturers have mostly changed to the new ratings. An equivalence chart is shown above.
The miniature circuit breaker (MCB) is now widely used and overcomes all the problems associated with ordinary fuses. It is a small, sophisticated unit affording a much higher level of protection than an ordinary fuse. It is tamper-proof and the unit involved is easily identified when one has tripped (the switch moves to the ‘off’ position). Most importantly, MCBs cannot be reset if the fault still exists; this eliminates the foolish and highly dangerous practice of putting in the wrong fuse wire or cartridge just to get things ‘conveniently’ working again for the time being. Read the rest of this entry »
A basic understanding of electricity is essential, even for those who do not intend to carry out any repairs or servicing of appliances. Ignorance is no protection against your own or someone else’s errors and oversights, whether with repairs, servicing or installation.
Power is supplied to an electricity substation at a very high voltage — 400,000 volts — in three-phase form. There it is converted, via a transformer, to 230 volt single-phase for distribution to our homes. In normal circumstances, current flows from the live supply of the substation’s transformer, through the electrical appliances used in the house and back via the neutral conductor (cable) to the substation transformer’s neutral pole (a closed loop). Read the rest of this entry »
