walters

How do i check if the Chassis is Live i don't want to touch my hands on the chassic because thats like 300Volts going straight into me and thats a bad shock is there ways to check methods for a Live chassis

I seen the AC wires REVERSED and that causes the chassis to be live
but every piece of gear is different so how do you know if the chassis it live when you turn on the piece of gear without putting your hands on the chassic ?

Dean Huster

With a hot chassis, always plug the hot chassis item into an isolation transformer. Then you are free to connect an oscilloscope or VTVM (both are typically referenced to earth ground) to the chassis without fear of destroying something.

You can buy isolation transformers or you can make your own by putting two identical transformers of decent power capability back to back. For instance, if you have a couple of identical "filament transformers" capable of 6.3 volts at 20 amps, you can connect the two 6.3v secondaries together, plug one transformer into the mains and use what was formerly the primary of the second transformer as an isolated secondary with the same voltage as the mains. In this case, you'll be capable of handling equipment up to around 120 watts. There will be some losses and inefficiency in the two transformers, so give yourself a bit of a cushion under that 120 watts.

Dean

__________________
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

walters

I seen someone use a AC pilot light and put there finger on one end and the other end went to the chassie if that AC pilot light lite up it has Live

walters

What makes or cause a chassis to become HOT or live?

walters

If the cables of the AC line wire is connected normal what would make the chassis HOT or live ?

Phasor

The purpose of the EARTH / GROUND connection is to prevent the case becoming live. If the case should become live, either earth leakage protection, or overcurrent protection should operate (trip), thereby removing supply.

If the earth connection is open-circuit, and you get an internal fault in your appliance, there is no path for the earth leakage current, thereby livening up the case.

With regards to checking for a live chassis, you can usually use a voltage proximity detector, otherwise known as "voltfinger" or "voltstick".