Festive lights go with a bang
With the festive period fast approaching and the decorations going up, a fortune will be spent on Christmas lights in 2017
Whilst they make everything glow, they can also be dangerous, especially when it comes to Christmas tree
lights. According to the US National Fire Protection Association, Christmas tree light fires caused an average
six civilian deaths every year and $14.8 million in direct property damage between 2011 and 2015.
How many of us have plugged our Christmas lights in, only to find they short-circuit all the power supply? Not
to mention the impact that twinkling and flashing lights are having on our power distribution system.
So, with our ‘elf and safety’ hat on, I would like to offer some simple tips to make sure that the only
thing that goes with a bang this festive season is your Christmas cracker!
The key to Christmas light safety is very simple – make sure you use a Miniature Circuit Breaker (MCB).
Why? Because festive lights put additional loads on circuits. As long as the loads are distributed across several
circuits, it won’t be too big to cause any issues. But, if the load gets too large, then the MCB will trip and your
lights (and the rest of your house) will be plunged into darkness. Not what you want on Christmas Day, when
you have a house full of people.
So, how does the MCD work? Although it’s small, an MCB is a clever device that protects wires from overloads
and short-circuits. For overload protection, the temperature of a bimetal through which the current passes is
decisive. If the nominal current rises slightly, the bimetal heats up to a greater extent, and after a certain
amount of time, this causes the switching mechanism to trip.
Short-circuit protection is located in the MCB’s electromagnetic coil. In the event of a short-circuit, the current
rises very sharply and the coil creates a magnetic field that both trips the switching mechanism and opens the
contacts via a quick release mechanism. This additional quick release for opening the contacts in the event of a
short-circuit helps to keep the energy to a minimum, which in turn reduces stress on the wires.
In cases of a short-circuit or overload, the shutdown process results in an electric arc between the contacts of
the MCB. To extinguish the arc, which has a temperature of more than several thousand degrees Celsius, it
needs to be directed away from the contacts to the arc chamber. The arc chamber splits it into several smaller
arcs until the driving voltage is no longer sufficient and they are extinguished.