Safety in electrical testing (sort of)

On Sat, 11 Oct 2003 20:03:03 +0100, "john" Gave us:

You need to build a cage around the test bench. At 33kV, I'd go for at least a 3 meter cube.

The idea is that the tester can NEVER be in the cage during energization.

This allows observation, but the switch gets thrown in a safe zone,

*outside* the cage. At these voltages, the fact that air ionizes so easily, and even easier in closed low flow spaces, the voltage levels should require the type testing I refer to, no matter how many techs are present.

A test cage is the safest bet, and make sure that pup is Well grounded, and of a good mesh size, not chain link fence, and of a good gauge, not chicken wire.

We use cold rolled steel seamed tubes at like 2" x 2" size 22 ga. and there is a nice small pattern steel link fence type mesh out there which we choose for good visibility. I think it was 1/2" size. We coat ours well so it can be an attractor, and a safety cage, but will not likely actually get a discharge if well coated. YOU MUST GROUND THE CAGE, however.

If you want to have lines that lead to another cage where you place test loads, fine. Just follow the same procedures.

Only energize when outside the cage, and never point fingers at HV sources. We use big variacs to bring things up slow as well, and look for shorts in this manner, so as not to just blatantly blow things.

Never point at HV sources.

You could become a high gradient attractor... but only once. :-{

Stay outside the cage, and make sure that all of your HV probes, etc. have their return wires in place or the meters in the cage will float high and get zapped (perhaps). No gear gets wired to a point outside the cage, unless it goes, protected, to another cage. Remain outside that (those) cage(s) as well during any test. NO wrist or heel straps!

Single test stations are common as far as I know.

4 engineers for 4 miilivolt-amperes?

Sounds like your MD is correct and 3 are redundant.

Unless, of course, you meant Megavolt-amperes, in which case there is a different reason why you should go?

I fought this battle with an electrical utility. The managers were only interested in $'s - safety and lives were secondary. Naturally safety was documented and preached daily - but the daily procedures showed the difference between safety and $'s.

The electrical operators worked as a team with all the other depts (including the managers) to maintain and upgrade our system.

I am not familar with UK regulations. Whenever we had a lineman or construction worker required to work to limits of approach an observer was mandatory. Your brief description creates other possible scenarios - control of the electrical environment being foremost.

One question that may put your issue beyond a conceptual $ number in some managers budget - what would be the cost to your company for the lost life of one employee in the knowledge, skill and experience the employee has, the payments your employee would make to his wife and children and the potential costs to your employer in legal fees and bad publicity. But, bottom line - does management give a SH** about their employees or only about $'s?????

To discuss this issue further - I use recyclecomputer @###somewhere hotmail.com I would prefer a direct contact email.

----- I have done tests in a small HV lab (300KV AC ,15ma ) which was designed by a professor who gained his experience in UK. This lab had a grounded steel mesh cage around the periphery and all controls were external to the cage. The gates were interlocked with the power supply for the test apparatus and , in addition, the procedure was to pick up an insulted rod with a grounded hook on the end and after shutting off power and also opening the gate (double protection), hanging the hook on the "hot" lead to ground it (level

3 protection). The latter could be forgotten but it became second nature. It is foolproof but not damfoolproof (which is impossible). In industrial conditions, the intention is to make the process as near "damfoolproof" as possible so demands and protocol are more stringent. The MD may be right but ask him what the company's situation and costs would be for a fatal accident of a single worker where there is a legally strong possibility of this being avoided with a second person present. Compare the cost to what Lloyds would charge.

On Sat, 11 Oct 2003 21:52:13 GMT, "Don Kelly" Gave us:

Well, there should ALWAYS be someone in the same lab, but single work station setups was the query here. As long as you are not totally alone, you are not alone. That is an easy policy to run through.

Ask for documentation reflecting the "policy" change {and written clarification of that documentation as needed} for the new procedures.

Notes or printed evidence of "old" procedures could be contrasted. You might want to clearly differentiate what changes were authored by the new manager, what consensus references he is using, and what in-house review he has done to support the changes, possibly with respect to portions of workplace regulations like

29CFR1910.

You might also review operational procedures issued by manufacturers of the test equipment used.

For a research environment where closely defined electrical safety is routinely addressed commensurate with risk, you might try online materials like llnl.gov/es_and_h/hsm/doc_16.01/doc16-01.html There are a number of reference links there that may be applicable to your work. Although these procedures represent safety boilerplate within that organization, often as a condition of procurement for services by vendors, contractual agreement to the same procedures is specified {and subject to onsite audit} as a condition of purchase-order conformance/completion.

--s falke

You can also play him along the lines of "where's the risk assessment?" which I believe is mandatory by law (Health and safety at work act) in the UK. This should outline the dangers involved and measures put in place to minimise the risk, and quite correctly, argue your points. Hope this helps, Paul F.

background)

Welcome to the world where MBA's make decisions about the bottom line. I worked for a company for 5 years that had boiler plate about needing 2 men on anything medium voltage. The rule was NEVER followed. It was common pratice to send one man for a two man job.

The bottom line is all that matters now. Be safe and be careful you are not alone in this situation.

Yep!

Someone should "be in the area" in case something goes wrong. Aside from everything else, there usually is some kind of "panic button" which will power down much of the stuff. The problem is, of course, that high voltages can charge caps with enough energy to do serious damage to people and material. So even after the "panic button" has been pressed it can still be dangerous to come to the aid of someone who is down.

Frankly, were I engaged in high voltage testing I would much prefer to work alone. I would not trust my helper with my life and I would not expect him to trust his life with me.

If a second set of eyes is desired in case of accident to help in the accident investigation, the "eyes" can just as well be a video recorder.

The second person is for the CPR, choose your lab partner accordingly.