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What happens when an every-day part of our home life starts to fail? In this case a standard 2 gang dimmer switch began to fail overtime to the point that it became a dangerous fire hazard.
On this night we received a call with reports that a light switch in a holiday apartment on the Esplanade sea front of Tenby had suddenly started smoking with a flash of light and the lights went off on one of the dimmer switches, and the other was unable to be turned off.
A dimmer switch works in different ways depending on the type of lighting load requiring dimming, in this instance it was a traditional leading edge dimmer which was commonly used to dim the original halogen lamps (bulbs) of days gone by.
We arrived at 22:15 and the switch was hot to the touch. There were audible sounds of arcing and crackling from behind the switch plate. To assess what was happening the faceplate was unscrewed and we were met with this - a smouldering dimmer switch with sudden ignition from the smouldered plastics.
As we’d not attended this property before we were unfamiliar with the layout and the location of the consumer unit. As the switch was actively igniting a decision was made to cut the live conductors with VDE rated electrical cutters to disconnect the live supply to the switch to remove further danger. This was done with extreme care and professional experience, to remove the risk of further ignition.
Why did this happen?
After locating the consumer unit and disconnecting the supply, work began on removing the damaged switch and dry lining back box. The conductors appeared to be intact within the terminal, but the entire terminal came loose from the box. This could have been due to electrical heating of the dimmer switch as the dimmer aged, which continued to escalate over time to the point where the heat accumulated enough to smoulder and begin the stages of fire production. When subjected to heat, the plastics begin to carbonise which gives off their own gases which can become flammable. This was evident when the faceplate was removed from the box and the conductors were able to arc which provided an ignition source to the gases.
How did we fix this?
As this was a late Saturday night call out, we replaced the dimmer switch with a standard 2 gang rocker switch and dry lining back box. After connecting this we issued an Emergency Call Out Record and inserted it into the Welcome Folder in the property for a paper trail.
How could this have been prevented?
Holiday apartments in Wales are subject to Welsh Government regulations on accommodation for sleeping guests that state such premises should receive an EICR (electrical installation condition report) every five years at minimum - although these can be done more frequently at the owners request.
Had the property have had a recent EICR carried out by a reputable electrician, this could have been picked up during the inspection which would have identified a potential breakdown at the switch and been replaced immediately.
What happens in an EICR?
All inspecting electricians carry out EICRs differently, so here we will outline how we carry out EICRs.
When first arriving to a property we conduct an initial walk around of the property to try and identify any blatant non-conformities and note them down. We then identify the protective Earth bondings to non-electrical services such as the gas and water supply.
After removing the cover to the consumer unit we then isolate the supply and carry out the necessary live testing and record the results.
After the live testing we then carry out the “dead testing” which includes confirming earth continuity on all circuits, end to end testing of ring final circuits (socket circuits), and insulation resistance which gives an understanding on the health of the cables.
We inspect various accessories (sockets, switches and light fittings) to check terminations and and conductors visually. Where poor results are found we then inspect more accessories to get an average overview of the installation.