ELCB's, RCD's and Breakers
ELCB, RCD, MCB, Wired Fuses, Whatever you happen to be using in your home at the present time, it is important to understand the differences and how these differences affect your home safety.
MCB or Minature Circuit Breaker is a protection device designed so as to cut out, or break the electrical supply when a preset current level is exceeded, they come in various rated sizes, ie: 5A, 10A, 15A for domestic installations. They are a step up from basic wired fuses, but should be replaced when ever possible with ELCB's of equivalent rating for improved safety and protection.
ELCB and RCD are two different names for the same device, ELCB is usually the term referred to when talking about usage in relation to the household consumer unit (Fuse Box), and the term RCD is more commonly used when referring to portable plug in devices such as a device that is plugged in first in order to protect when using a lawn mower or other hand held electrical equipment.
These devices, RCD's and ELCB's work by detecting any difference between the outgoing current and the returning current which should be equal under normal working conditions, but when something goes wrong like cutting through the cable with your lawn mower, the the outgoing current would increase, probably quite dramatically and would exceed the return current as current would now flow to earth, making the RCD trip out and cut off the current flow, so offering protection and possibly life saving protection.
These types of devices when installed in a home consumer unit with the appropriate values for the various household circuits can considerably reduce the amount of damage sustained when an electrical equipment failure occurrs, An example of this would be a fan oven element failure when the element breaks down and current in the element leaks to earth by tracking from the filament to the outer steel casing of the element. Without an ELCB fitted the leaking current will have to increase to the full value of the circuit breaker fitted and exceed this value for a not-insignificant amount of time before it will trip out and cut off the current. During this time, with the full amount of current now flowing through part of the element to earth, there is a considerable opportunity for burning and therfore damage to the cooker to occur before the breaker or fuse actually trips and cuts off the current. This can be seen when the faulty element is removed by a "welded metal" like the appearance of part of the element and even maybe damage to the surrounding casing of the oven.
On the other hand, the situation would be totally different if this same problem occurred and an ELCB was fitted instead of a MCB or a wired fuse, as soon as the fault occurs and the leaking current exceeds the device trip current it will react and cut off the current immediately, avoiding the consequential damage that the faulty part could possibly have caused.
ELCB's are a definite worthwhile investment for the safety and protection they offer to a modern home, with so much electrical equipment in use in a modern household, especially low current devices that stay plugged in continuously in many homes, for example TV's DVD's and games consoles left on standby, charging units for telephones and many other portable devices that are battery-powered, all of these types of power supply units develop a small amount of heat and are therefore a possible source of fire in the home and it is therefore of utmost importance that an ELCB of the correct rated value be fitted as this will cut off the supply current very quickly after a fault occurs, thus cutting off the fuel, (electric current) to the faulty equipment and preventing any consequential damage!