ECM: Shipyard Electrocution

[George Stolz]

Did anyone read the article in the 08/06 issue of ECM about the shipyard journeyman that was electrocuted working on a transformer?

I was left with a few questions after reading it.

In the beginning, the man was referred to as a journeyman. Later, it says he was unlicensed. What gives?

The article also said the transformer was de-energized. How did he get electrocuted?

Gotta run, so I can 't go deeper. Comments?

 

[celtic]

I seem to have let my subscription to EC&M lapse

BUT...
to take a stab at the 2nd Q: the man was referred to as a journeyman. Later, it says he was unlicensed. What gives?

A: A journeyman does not neccessarily need to be "licensed". Not all states have the same requirements. NJ for example, has Licensed ECs and Licensed Journeymen - but no one enforces the LJ requirement.

What state was this in?

Depending on the voltage of the transformer, it could have had some "residual" voltage in the line...or...in the case of a MV/HV transformer, if not grounded out, a voltage could be induced into that feed from adjacent MV/HV lines.

 

[peteo]

George,
I value reading what you say here on the forum. Inadvertently my words will touch on a nervy subject, Cal shipyards, but I've made every attempt to try to answer the questions and avoid having your thread get sidetracked.

That article concerned an October 28, 1992 incident here in California.

1) Journeyman probably refers to the victim?s job title at the plant, is my guess. To quote the FACE report, ?facilities journeyman electrician.? The distinction is not touched upon, so it's not made clear. It appears that the author of the report simply assumed that an experienced electrician with that job title could be called a ?journeyman? without having the state licence.
2) CAL-OSHA rules at the time allowed an employee to service anything, as long as they were ?trained.? This rule was open to interpretation by employers.
3) The coroner?s report is alluded to in the article, but without substantial results from that inquest. The attending M.D. presumably found that electrocution would have caused the internal injuries, but no mention is made of specifics, i.e., whether hairs were found on a bobbin or even what conductive surface(s) or source(s) of power were involved.

Here?s a proviso from the article:

Editor's Note: This article was excerpted from a FACE report with permission from NIOSH. All FACE reports involving electrical injury and fatalities can be accessed on the Web at www.cdc.gov/niosh/face/default.html.


Here?s the report the editor is alluding to:

http://www.cdc.gov/niosh/face/stateface/ca/92ca016.html

 

[George Stolz]

Peteo, thanks for providing that link. All things being equal, I should have followed that before posting - it's cool that you linked straight to the story for me.

Here's one of the things in the article that was mentioned several times, and I am quoting this from the linked report:

Recommendation #3: Employers should have a proper ground in place for all electrical power mounds and equipment.

Discussion: This incident may have been prevented if a ground had been in place at the south power mound. Excess electrical energy in the cables at the power mound that evening may have been the reason the victim was electrocuted. Under Title 8 of the CCRs section 2943 (f) suitable grounding devices shall be used. They shall be first connected to a ground before being brought into contact with any de-energized conductors or equipment to be grounded. The other end shall be attached and removed by means of insulated tools or other suitable devices. When removed, they shall be removed from all conductors or equipment before being disconnected from the ground.

One, I don't understand the process they're describing. The last sentence in particular confuses me.

Two, is the purpose of connecting the normally ungrounded conductors to the earth to relieve any "residual" voltage in those conductors? If so, how does "residual" voltage occur? Capacitors on the load side of the transformer? I just don't understand how someone can get shocked or electrocuted from a transformer that has been shut off.

That knowledge may save someone's life someday.

 

[mdshunk2]

Higher voltage transformers and semi-con cables can turn into big capacitors. You can be electrocuted by a high voltage cable that is not presently energized but has not been grounded. Same goes for your bucket truck. You can be working near higher voltage lines and turn your truck into a big capacitor if you don't ground your truck.

 

[jim dungar]

One, I don't understand the process they're describing. The last sentence in particular confuses me.

They are describing the action of using "jumper cables" thereby creating a three phase bolted fault connection to ground.

NFPA70B is a good source of information for safe electrical maintenance work.

 

[mdshunk2]

They are describing the action of using "jumper cables" thereby creating a three phase bolted fault connection to ground.

NFPA70B is a good source of information for safe electrical maintenance work.

For slang, we sometimes call this process "hanging grounds". Sometimes you'll hear people improperly calling this procedure "hanging macs" which more properly refers to jumpering around live equipment rather than grounding it.

For transformers, AB Chance makes the more popular temporary grounding jumpers. The C600-0729 is a popular one. You jag it in where the elbow was unplugged and clamp it on the ground.

 

[Rockyd]

George,

Go here- http://www.hubbellpowersystems.com/powertest/tips_news/pdfs_best/09-9001.pdf

These guys can save your life! After testing to see if it's dead, you then apply these jumpers from ground to all three phases in a transformer, or anything else (like disco's in the swithch yard) you think you need an additional level of protection while working on.

 

[George Stolz]

Thanks for the info!

I'm still letting it sink in.

 

[H.L.]

You can check out Hi-Line Supply in Elgin Illinois. www.hilineco.com and look under grounding in their online catalog.

http://www.hilineco.com/pdf/91-102.pdf

H.L.

 

[George Stolz]

I just can't shake the impression that the procedure being described in the pdf Rockyd linked to are working live, which makes much of it either wrong or confusing.

 

[mdshunk]

I just can't shake the impression that the procedure being described in the pdf Rockyd linked to are working live, which makes much of it either wrong or confusing.

Yeah, hanging the grounds with the hotstick might give you that impression...
... they're "working it like it's live" until it's grounded to drain off the capacitive charge and assure that everything's at the same potential. This will also assure that the reclosers will open or fuses will blow if that section is accidentally energized for some reason.