Personal Protective Grounding

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Personal Protective Grounding

Post  BC_boy on Sat Apr 07, 2012 7:53 pm

IF IT ISN'T GROUNDED, IT ISN'T DEAD!















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Re: Personal Protective Grounding

Post  rcdallas on Sat Apr 07, 2012 9:50 pm

That's a good informative write up on grounding BC. Real world some things may differ a little bit such as the company's method of grounding. Here we don't use equipotential (EPZ) grounding. Instead we use the bracket grounding method, however it's short circuited. There are other rules where you can't be more then 3 spans apart between grounds.

The engineers say nowhere on our distribution system the fault current will exceed I think like 17000 amps so we can use #2 grounds all day long - I am willing to bet almost all utilities can get away with #2 grounds.

When working major storms they'll go so far as ground the line AND wear rubber gloves. When we get into some certain underground equipment there is no way of grounding it by the book, you might have to isolate THEN touch ground to bleed off the capacitive charge that URD cable presents.

Not too long ago we tested all our grounds on this ground tester machine-ma thing deal. Simplest way to repair ground sets is to brush them...seen it first hand how brushing the duck bills makes a big difference.

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Re: Personal Protective Grounding

Post  Highplains Drifter on Sat Apr 07, 2012 10:03 pm

rcdallas™ wrote:Not too long ago we tested all our grounds on this ground tester machine-ma thing deal. Simplest way to repair ground sets is to brush them...seen it first hand how brushing the duck bills makes a big difference.


Can I assume if you don’t brush the duck bill that you do not brush the wire where you are installing the ground or applying a light coat of grease in the ground’s jaws? Brushing the conductor is one practice I always do.
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Re: Personal Protective Grounding

Post  rcdallas on Sat Apr 07, 2012 10:18 pm

I won't deny it, but no I haven't always. Speaking of here's a good one. One night about a year ago another guy and I were working a broke pole. We decided to ground the 240v street light circuit as it was fixing to be dark soon. It was 6cu conductor. We grounded both ends of the street light at our work point and before doing so brushed the snot out of that copper before placing grounds.

We we're at about the end of the circuit that ran for a LONG ways. After we got everything transferred over to the new pole, as I was removing my grounds it drew and arc. He removed his and drew one hell of an arc. Transformer being so far away thought it was load! Smile


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Re: Personal Protective Grounding

Post  BC_boy on Sun Apr 08, 2012 12:48 am

OK Disclaimer: This is merely a guideline meant to inform of the principle and to learn about the concept of personal protective grounds. Always remember to inform yourself of and follow the rules and procedures used by your particular company. study Cheers!
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Re: Personal Protective Grounding

Post  hotwiretamer on Sun Apr 08, 2012 12:24 pm

We are now using the "Cable isolation method" with our URD. You isolate, test, ground, and then remove the ground off the feedthrough stand-off. On a feed through it is isolated from all sources of system energy. This method keeps you clear of fault current off of the conentric as long as you are on a ground mat at work location. There is no difference of potential between the isolated cable you are working on and the concentric neutral you are in contact with.

It's a tough pill to swallow when you are use to grounding your URD when working on the other end of the cable!
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Great Thread BC_boy

Post  topgroove on Sun Apr 08, 2012 6:56 pm

Let me first say thank you BC ,

I'm gonna share something I never told too many people before. The job was to replace a 34.5kv backlot vertical construction pole. I was an apprentice and eager to show what I can do. We had our clearence and tested dead and grounded at the road where we could get to everything with the truck.

Perfect work for an ape! everything dead and grounded. After we set the new pole with the track digger, I went to work. I tested dead again and installed three phase bracket grounds on either side of me with a pole mounted cluster ground on the pole at my feet. I created, as I was trained, an equipoential zone of protection.

Old school stuff with Brace and bit! Installed everything Transfered the conductors and cut down the old pole. I was so damn proud of my work...

The first thing your taught as an apprentice is to not stand on the hardware on a pole!
Let me be the first to say... After four hours in my hooks I was all over that hardware like a cheep suit. with 48 inch spacing between phases standing on the phase beneath you was the most comfortable position!

I finished up the pole and was admiring my work when I suddenly felt the most unusall feeling. I cant quite describe it, but it felt as if the whole pole jumped a bit?

I kinda brushed it off removed my grounds,,, dropped the handline and climbed down.. As a grunt, it felt great to have everybody say nice job Dave! Looks good. I felt great, One of those moments I guess!

We grabbed our gear and headed for our first set of grounds.. I remember asking if I could remove the last set of grounds! The foreman said relax Dave you did enough today!

The Journeyman was booming up in the air when suddenly,,,, Over the air.... Regional controll called out our truck number and asked if everyone was allright! You could hear the horror in his voice! We all kind of stopped and it was a WTF moment.

My foreman Had a cellphone.... It was one of those early model cell phones that was the size of a small suitcase. The phone looked like a full size, land line phone , (kind of funny for the young guys).

He knew the guys in regional controll and gave them a call.... Turns out, the regional controll day shift had completed all the paperwork to clear the clearence on the line we were working. They had all the paperwork ready and waiting for the afternoon shift.

The afternoon travelling opperator that did the switching simply grabbed his switching orders off the desk like he had done for the last twenty years. Simple routine stuff, stuff he does every day without even thinking anymore. Kinda like grabbing your morning coffee.
Guess he figured he'ld get his work done and skate the rest of the night? ( I guess, could be wrong). After all, he had all the paperwork... all signed and ready to go... Can't really fault the guy.

When He got to the breaker and removed the tag and closed in...... Sending 34.5kv directly to the line I was literally standing on phase to phase! I hardley felt a thing... in fact I had no idea at all the line had become energized. Just a little jump and maybe a tiny crackle or arc sound? not really sure what it was at the time?

When the journeyman removed the grounds at the road out of the bucket he noticed three perfect burn marks on the 4/o copper conductor underneath the ground clamps.

Burned and melted it so perfectly we had to re-issue the clearence, test dead, re-ground and splice out the conductors.

Those grounds saved my life! I had no idea at all the line was accidentally energized
No ones fault really.... just a simple failure to follow proper procedure! That little unfortunate incident that happened, changed forever the way regional control did business. We all studied the sequence of events and figured out a way, that that senario could never happen again.

Bottom line is.... Properly installed grounds will save your life. You can have an accidental 230kv energization and if you have your grounds around you and you and you are at the same potential as the system voltage you are as safe as in a newborn in its mothers arms!
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Re: Personal Protective Grounding

Post  hotwiretamer on Mon Apr 09, 2012 2:00 am

I'm glad that story had a good ending Groove.

That Hoover line we are working on is obviously isolated and grounded. My grunt wanted to climb a new pole on a change out on that line. I told him the only way he was going up was if our cluster ground would fit around the new pole. Unfortunately for him the chain binder was not long enough. (H4, 70') he was a little pissed, but understood the situation. After reading your story I feel better that I didn't let him go up!

Thanks for the post.
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