[Amps] HV SAFETY QUESTION

[ka1xo at juno.com]

Ladies and Gents,

Realizing the last posting was not entirely serious, my apologies ensue.

However, the reason for getting your attention was based on a more previous posting where characters keyboarded into my system didn't print on some members' screens and there were misinterpretations of
capacitance values, etc.

The posting yesterday about skin resistance in the same paragraph as mentioning the HV rectifier and filter section was plainly understood by me, but I think of the neophyte here, as having to think about the possible untrained help my contractors sometimes employ.

We have a system of controls for workmanship and safety in our industry that are called MOP's, or Methods-Of-Procedure. These documents, when dealing with connections in the power plants our project oversees, must be very precise, because one slip can mean death or serious injury.

Case in point: Last month a contractor was tasked with a power plant job that had a line item of connecting new unfused cables from a storage battery through a 1200 ampere circuit breaker, to the charging rectifier. This contractor crew previously completed similar tasks in power plants that had one giant string of cells. In this circumstance there were two strings in parallel, and the MOP used, unbeknownst to me, was for a plant with only one string.

The contractor foreman gave the battery cell disconnection task to an apprentice. The apprentice had no clue. He dropped a live, unfused, 4/0 AWG cable lug on a bussbar energized with the opposite polarity right in front of his face and the explosion blew molten lead and copper into his safety glasses so hard it melted the lenses. The kid was burned, but not blinded.

We all kid around talking about getting zapped by our power supply voltages, and all of us have had first-hand experiences we care not to ever repeat. 

However, I think we should all be careful that what we talk about should be accompanied by a suitable warning that the wrong move may be someone's last.

Respectfully,

Hal Mandel
KA1XO