In the course of our work we come across some "interesting wiring. some of the more interesting items are shown below. Contributions will be most welcome.

	How Not To: Plug into shore power. Domestic flex, a 13 amp plug and socket, rain & seawater. SHOCKING!!!
How Not To: Treat a relay. This poor relay had been left with the power on whilst being immersed in sea water. Surprisingly it didn't work. In fact it was quite happy turning a starter motor the second the battery isolator was turned on. Seawater and electrics do not mix.
	How Not To: Connect wires together, especially in an engine bay. Connections like this are the frequent cause of equipment failure or fires.
How Not To; Treat the wiring to your bilge pump. You will be surprised to hear that this bilge pump no longer works. The best bit is that the supply to the bilge pump was direct from the battery using a bit of old bell wire with no fuse. In military terms this is known as a "detonator".
How Not To: assume that because your engine is new everything is OK. This well made terminal prevented a one year old Volvo engine from starting. This is the negative cable to the engine block. The engine was painted with Volvo green paint and the terminal had been fitted over the paint. The contact with the engine block was poor but sufficient for it to work. After a while small sparks built up a deposit causing the connection to fail. The repair was simple and low cost.
	How Not To: connect battery cables to the rest of the boat. In this example two cables connected to the battery were connected to a multi-core cable. This was then used to feed the rest of the boats electrical system. The red and black battery cables were taken from an industrial application and each cable only had six strands of copper. This type of wiring is typical of a home made job and is one of the main causes of devastating electrical fires.
How Not To: connect NMEA data cables. This connection box was used to try and send data from a chart plotter to among other things a DSC radio. The wiring is a combination of domestic three core cable and burglar alarm wire. Sea water has penetrated to connection box and corrosion has set in. The use of block connector is not recommended for data cables.

Marine Electrical Ltd 17 Margaret Street Beaumaris, Isle of Anglesey, LL58 8DN Company Number 4640817