Electrics problem - shocks from washing machines

Owain_Moneysaver

ormus wrote: »

by the same token, a multimeter can fail and give you misleading info. with potential lethal results.

That is why you should:

1. Have equipment calibrated annually
2. Check equipment between calibrations using a test box or proving unit

And in particular when testing for live conductors the procedure is always

1. Test a known live voltage source
2. Test the conductor in question
3. Retest a known live voltage source

Health and Safety Executive Guidance Note GS38

This is fail-safe as if the tester fails between 1 and 2 it will be shown at 3. If it fails between 2 and 3 you assume the conductor is live and the tester is faulty.

"Design and Verification of Electrical Installations - Brian Scaddan"

Search your tool boxes: find, with little difficulty one would suspect, your 'neon screwdriver' or 'testascope'; locate a very deep pond; and drop it in!

Imagine actually allowing electric current at low voltage (50 to 1000V ac) to pass through one's body in order to activate a test lamp! It only takes around 10 to 15 mA to cause severe electric shock, and 50mA (1/20th of an ampere) to kill.

Apart from the fact that such a device will register any voltage from about 5V upwards, the safety of the user depends entirely on the integrity of the current limiting resistor in the unit. An electrician received a considerable shock when using such an instrument after his apprentice had dropped it in a sink of water, simply wiped it dry and replaced it in the tool box. The water had seeped into the device and shorted out the resistor.

keith969

Owain_Moneysaver wrote: »

"Design and Verification of Electrical Installations - Brian Scaddan"

A pity his advice is clouded by factual inaccuracy. A neon lamp - with or without a current limiting resistor - will not 'register' any voltage from 5V upwards. Typically they require a minimum of ~90V to strike a discharge.