Need help with cracking those EICR codes? The technical team at NAPIT, with the help of the 18th Edition Codebreakers publication, answer your latest coding queries. Click on the photos for a closer look!
ANDY NEWELL: HERE ARE TWO PHOTOS TAKEN AT MY DAUGHTER’S HOUSE. THE FAMILY HAD SMELLED SOMETHING STRANGE AND I NOTICED A DOUBLE SOCKET AT THE BACK OF A CUPBOARD FEEDING THE DISHWASHER AND WASHING MACHINE. THE PLUG WAS FOR AN EXTENSION LEAD, AS THE SOCKET WAS TOO FAR AWAY FROM THE WASHING MACHINE. THE LIVE WIRE BURNED BACK COMPLETELY BEFORE THE MACHINE STOPPED AND THE BREAKER IN THE CU DIDN’T TRIP AS THE NEUTRAL AND EARTH WIRES REMAINED INTACT.
We often see socket outlets with thermal damage. There are numerous reasons why this happens, but in this case, the damage is more from heat transferal from the plug, looking at the localised dark patch just above the Live (Line) pin outlet. Even though an extension lead is classed as portable equipment, being used in this manner, it is very much seen to be a part of the main electrical installation. Where washing machines and mobile loads that generally have a high current rating are used, it’s best practice to install a local socket-outlet and not rely on extension leads.
Looking at the extension lead plug top, it looks as if the Live (Line) terminal was loose and causing excessive localised heat and quite possibly arcing. We can also see that the plug top may have been wired by someone other than its original manufacturer, which could easily be the source of the loose or arcing conductors, causing the thermal damage. As the Live (Line) conductor has been burnt back to the overly tight cable clamp, we can assume there may well have been some arcing in this case.
These types of problems arise from a poor understanding of load management and are usually only found when things go wrong or on an EICR. This kind of potential fire risk is exactly the reason BS 7671 has started to favour the introduction of Arc Fault Detection Devices. Even though BS 7671 doesn’t normally concern itself with equipment fitted to the electrical installation, a ring-final circuit protected with an AFDD would likely have detected this kind of arc fault and isolated the circuit to make it safe.
Three things would have prevented this issue:
1. Following industry guidance and putting socket-outlets where they are needed. There’s still no guarantee the plug top used won’t have been incorrectly fitted.
2. Carrying out regular EICRs, as this will have had long periods in between checks, including portable and fixed appliances.
3. Using an AFDD – almost instantaneous, leaving the circuit safe until remedial action can be taken.
Looking at the three options, a continually monitoring AFDD is likely to be the safest option and will protect lives.
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