another electricution - metal street pole-baltimore!

[petersonra]

Re: another electricution - metal street pole-baltimore!

Originally posted by physis:
I just don't beleive that removing a ground rod will improve anything.

My guess is it might well convince people the green wire is completely unnecessary, making them even less aware of the need for proper bonding.

 

[physis]

Re: another electricution - metal street pole-baltimore!

Now there's Bob And Bob B.

Bob not B. now I'm thinking if they let me change the wire names maybe there should be a different name and color for bonding and grounding conductors.

 

[charlie tuna]

Re: another electricution - metal street pole-baltimore!

iwire and bob,
i never said i was against home inspectors because they were "unqualified". they may be qualified to the requirements of their municipality or state, but in relation to a typical residence they can do little to protect the new home owner from purchasing a home with existing electrical problems in it. i do not like the idea that they communicate a signal to the new home owner that their home is up to code or is clear of electrical problems. or like the example i wrote about-- suggesting that the aluminum wire in a house was against code. i put myself in the place of the buyer - i would much rather spend my money on an a.c. contractor to evaluate the condition of the a.c.system. a licensed roofer to check the roof--etc.. it would cost more but it would mean something.

the subject of the ground rod at light poles is very basic --- if it serves no purpose --- and it adds confusion to those maintaining it --- why have it? yes, education is the key! take away the thought that the ground rod connection renders the pole safe from being electrified. it is a step in the right direction. why require something on any job that has no function?

guys---the "home inspector" and the "ground rod" have one thing in common---neither have a meaningful function!

 

[iwire]

Re: another electricution - metal street pole-baltimore!

Originally posted by charlie tuna:
guys---the "home inspector" and the "ground rod" have one thing in common---neither have a meaningful function!

Both of those statements are opinion, you can not back either one with facts.

There are a lot of things HIs find that home buyers who do not have construction backgrounds would have not known about.

The ground rod can clear a fault if the steel pole is energized by a high voltage utility line.

 

[physis]

Re: another electricution - metal street pole-baltimore!

Isn't one of the purposes of a ground rod to try to keep the earth at 0 volts related to the service?

 

[George Stolz]

Re: another electricution - metal street pole-baltimore!

because what we are trying to do is maintain a low resistance path from the metallic parts of the pole back to the power source so that if a phase conductor comes in contact with any of these metallic surfaces it will cause the overcurrent device to operate and turn the circuit "off"!

C.T., sometimes the obvious answers are best. I'm slow on the uptake, thanks for clearing that up!

 

[physis]

Re: another electricution - metal street pole-baltimore!

The ground rod can clear a fault if the steel pole is energized by a high voltage utility line.

Are you sure about that Bob B.? (Bobby, he he)

 

[iwire]

Re: another electricution - metal street pole-baltimore!

Originally posted by physis:

The ground rod can clear a fault if the steel pole is energized by a high voltage utility line.

Are you sure about that Bob B.? (Bobby, he he)

First I hope you wear skirts because men do not usually call me Bobby.

Yes I am sure about my statement.

Even if the ground rod has 50 ohms of resistance a 7,200 volt line falling against the pole will produce 144 amps of fault current. I doubt very much that the utility OCPD will not open at that level.

[ January 05, 2005, 08:10 PM: Message edited by: iwire ]

 

[physis]

Re: another electricution - metal street pole-baltimore!

Then how in thunder blazes does a downed line stay energized?

[ January 05, 2005, 08:27 PM: Message edited by: physis ]

 

[iwire]

Re: another electricution - metal street pole-baltimore!

Originally posted by physis:
Then how in thunder blazes does a downed line stay energized?

My best guess would be lack of good contact.

 

[physis]

Re: another electricution - metal street pole-baltimore!

I'm thinking that too.

 

[physis]

Re: another electricution - metal street pole-baltimore!

I haven't seen Charlie all day

Edit: I hope you haven't made him mad Bob. :roll:

[ January 05, 2005, 08:42 PM: Message edited by: physis ]

 

[roger]

Re: another electricution - metal street pole-baltimore!

Sam, I noticed that too, hopefully he is just busy.

Roger

 

[charlie tuna]

Re: another electricution - metal street pole-baltimore!

you have to remember something in relation to the ground rod --- what is the impedance of the ground rod to the power source. thats what will determine how fast the fault can get cleared! weather it is the primary or secondary power -- the pole gets energized by a power source ---what is the total resistance back to the power source?

 

[hurk27]

Re: another electricution - metal street pole-baltimore!

Bob there was a video on here some where, of a lumber truck that had it's hoist cable touch a power line. the truck was destroyed and the arcing was still going. They must fuses these lines high. Charlie tuna A ground rod will have very little effect on opening a OCPD. At a 120 volts to ground there would be very little current added to the fault to cause the OPCD to open.

 

[iwire]

Re: another electricution - metal street pole-baltimore!

Originally posted by hurk27:
Bob there was a video on here some where, of a lumber truck that had it's hoist cable touch a power line. the truck was destroyed and the arcing was still going. They must fuses these lines high.

As always it would depend on what lines you get involved with.

 

[physis]

Re: another electricution - metal street pole-baltimore!

Was that just one wire?

Because, what about rubber tires?

 

[iwire]

Re: another electricution - metal street pole-baltimore!

The rubber is not enough of an insulator once the voltage is to high.

Of course they may add some impedance until they melt and the rims hit the pavement.

 

[charlie tuna]

Re: another electricution - metal street pole-baltimore!

home inspectors:
the inseption of the "home inspector" has just come about in the last ten years or less--from my knowledge! how did we sell homes prior to their existance? just like the "new home owner's insurance" --- how did we get along without it?
these are things that make the realtors job easy but does not cost them anything.

ground rods:
remember, a 120 volt pole fixture on an ungrounded pole can have 780 volts on it if the capacitor lead comes in contact with the pole.

primary fusing:
i recently was called to a job where an electrical contractor set his nextel cell phone on top of a 800 amp breaker while he closed it! the vibration of the breaker caused the cell phone to fall into the open panel's bus and set off a major melt down. the line side of the panel went phase to phase and the service wires burnt back into the primary vault. melted the 4" inch rigid nipples thru the vauld wall! the primary fuse (50 amps) never blew! the potheads on the pole out on the street were on fire when the fire department arrived! the actual problem here was that the vault was miswired. the customer's neutrals were made up to the vault's ground bus. this ground bus was connected to the vault's ground loop by a(1) number one copper wire which blew in half when the short started. since the short was phase to phase -- the primary system saw the load as a heavy load ---no return path via the neutral.

[ January 06, 2005, 07:43 AM: Message edited by: charlie tuna ]

 

[petersonra]

Re: another electricution - metal street pole-baltimore!

i wonder how much this little incident will cost that EC?

there goes this year's bonuses!