A few weeks ago whilst carrying out regular daily maintenance in the fish house, I heard a “crackling sound”, at first this sounded like running water, I then smelt burning and noticed thick smoke from the terminal (chocolate) block in the following photograph. I quickly shutdown all electricity in the fish house. To investigate the problem further.
This 15Amp terminal block was used to connect a 500Watt (approx 2-3Amp) heater to an external thermostat. As you can see from the photograph, it’s been completely destroyed, melted and fused.
On further investigation I found that the solder used to “tin” the wires had degraded, causing a gap between the electrical contacts in the terminal block and wire. This gap caused an electrical arc, hence the crackling sound, the heat caused by this electrical arc was responsible for melting the terminal block. This heater is thermotstatically controlled, so the heater is only on for very short periods.
I understand that the practice of “tinning wires” in electrical appliances is no longer performed for this very reason, solder breaks down with age, exposure to air (oxidation) and can cause fires. Wires in electrical appliances are now terminated using bootlace ferules.
Tinned copper wires and wires terminated with insulated bootlace ferrules.
I’ve now started to remove all tinned wires using solder and replace with insulated bootlace ferrules. in the fish house.
insulated bootlace ferrules. in use, when connecting heaters to an Algarde DigiTherm external thermostat.
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