Friday, February 24, 2012
Wheres the ground on this machine?
Once again another case of a lazy ass hole putting lives at risk and violating NEC and Major OSHA
Rules but what does he care he got the machine wired and working .
The machine in question is used to grind and sharpen very large size drill bits like those used in machine shops. It can be wired for either 230 or 480 3 phase power.
Normally this would be done with a piece of 14/4 rubber SO style cord.
But apparently this machine was wired with metal green field which is allowable as it provides for a proper ground but the problem it the idiot instead put a 3 wire plug on the end of the greenfield which is not permitted by NEC code . The plug is designed to be used with flexible SO and SJO type cable only . Instead It should have been terminated into a grounded metal junction box.
With this set up there is no safety ground to remove electrical current on the metal case of the machine in case there would be a malfunction in the machine which would allow a live conductor to make contact with the case, any one going over and starting up this machine could receive a severe to fatal electrical shock because the ground is not present.
At one time back in late part of the 1800's up till 1940's it was common practice not to ground machines so that they could stay operating until a line of machines could be shut down and repaired. This prevented the whole line having to be shut down and productivity could be maintained. The shop power bus would have 3 usually red light bubs tied to it and when one of the bulbs went bright it warned there was a problem.
If a bulb went out it meant a phase went out and the line needed shut down till the phase came back on. Unfortunately with this situation electrical engineers eventually found out this was a very bad arrangement because ground faults would not be repaired and eventually you could have a catastrophic run away surge which would take out all motors on the machines on the power bus. With properly grounded motors not only do you have safety but you avoided the run away surges.
Obviously who ever wired this machine was from the old school of wiring where we never ground anything But more than likely it was a do not give a dam to care I can wire anything idiot.
Putting any one operating this machine in danger.
Posted by Nick Markowitz Jr. at 5:48 PM