Care & use of short circuiting devices
Short-circuiting devices should be maintained to a standard that ensures it is fit for purpose.
Guide To Selection Of Appropriate Earthing And Short-Circuiting Conductor
Higher temperature levels are now allowed under IS EN 61230:2008 to accommodate lighter equipment. The following Tables may be helpful.
COPPER -V- ALUMINIUM CONDUCTOR
Even though Copper conductor is heavier and more expensive than Aluminium conductor, (Aluminium is aproximately 60% of the weight of copper) Copper conductor offers a far superior temperature range and fault level aspect. The equivalent Aluminium conductor has a larger CSA but offers aproximately 60% of the current carrying capacity and similar working temperature range.
“A SAFETY PROCEDURE THAT DOESN’T WORK”
Current flows in all current paths. (Ohms Law)
Induced Voltage and the Transformer effect.
The presence of induced voltage may vary from day to day, hour to hour or minute to minute.
SAFETY PROCEDURES THAT INCREASE DANGER
Numerous tests prove that grounding a machine provides no protection to ground workers or machine operators.
Safe levels of current in the human body
There is a mistaken belief that a short circuiting device will prevent current flow in the human body “Not so”. An Earthing and short circuiting device can only limit the current flow through the human body.
Guide To Selection Of Appropriate Earthing And Short-Circuiting Conductor
Higher temperature levels are now allowed under IS EN 61230:2008 to accommodate lighter equipment. The following Tables may be helpful.
Principles of short circuiting for human protection
Human protection by a short-circuiting device is achieved by establishing the correct resistance ratio between the human body and the short-circuit jumper
GUIDE TO ELECTRICAL FAULT LEVELS
It may be safer to base fault calculations on Transformer “Let through levels”, than depending on Utility figures which are liable to change without notice.
THE VOLTS MAY JOLT, BUT IT’S THE MILLS. THAT KILL
A short-circuiting device will not prevent current flow in the human body, it will only limit current flow to safe levels if properly sized.
