Why appliances with metal cases need to be earthed

Our Team. Our Faculty. Behind the Scene. Tutorix for Schools. Contact Us. Reseller Opportunity. Follow us. Available on. All Rights Reserved. There are two pin sockets specifically for shavers which are often found in hotel rooms, so an adapter is not needed.

Does that mean there is no need to earth or is the reason to not earth such as a danger if earthed? This is an interesting question. And one I was looking to get answered here myself. In equipment with double insulation and a metal outer casing, which contrary to what people say does exist I have come across in the past a Marantz Amplifier and a Yamaha DX7 Synthesizer like this. The outer metal case is insulated from the inner chassis by a plastic chassis or the inner chassis is plastic.

Unless you modify the equipment there will be only a 2 wire cable supplied with no wiring going to the chassis so you cannot earth it anyway As long as the outer chassis is not connected to the internal electronics then earthing it will not effect the performance of the equipment. The only reason I can think where this might be the case no pun intended is that the metal chassis is screened to the signal ground lines and creating a faraday cage to stop noise.

Earthing it in this case would introduce noise into the equipment. Manufacturers have to prove its safe before they can get electrical safety approvals on their equipment. If the equipment is approved then there will be a label close to the mains input showing the power requirements and stating how it complied to electrical safety.

In the case of the Marantz amplifier I fitted a 3pin mains socket to replace the original 2 pin and fitted an earth stud in the chassis and took the earth wire directly to that. I then star bonded from there to all the other outer metal parts such as the lid and control panel. Anyone with the slightest knowledge of electrical theory can confirm that this is not how parallel circuits work.

Please do not spread misinformation like this. The earth wire usually carries no electricity. The earth wire is connected to the inside of an appliance that has a metal case. When the appliance is working correctly, the live wire supplies the electricity which flows through all of the components.

When functioning properly the live and neutral wires are connected to the motor - they therefore come into play when the machine is switched on. It would function just like the earthed machine. If the live wire comes loose the motor will no longer have a p. If it happens to touch the metal casing the case becomes 'live'. This will only happen if the live wire touches the case. If the neutral wire touched the case instead then the case would not be 'live' but at 0V - anyone touching it would therefore not get electrocuted - but the diconnection of the neutral wire from the motor would stop the appliance operating.

On the continent earthing is not common.