Working near energized 4160 insulated electrical cable

powerpete69

Senior Member
Location
Northeast, Ohio
Occupation
XXX
Thanks guys. The point is that when you double the voltage, you WAY more than double the power per resistance. If the resistance goes down as you say, then it is even worse than I am pointing out. But per same "theoretical resistance", I stand by my figures.

This also points out what happens when you put that 208V heater on a 240V circuit or similiar situations.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Electroporation often causes the victim to drop dead on the fourth day after appearing to recover from the initial electrical-contact trauma. Holes in the cell walls make it impossible to maintain electrolyte balance.
None of it’s pretty. I know a few older people with burns and missing limbs that I consider lucky.
The one I witnessed was laying under a 13.2kV line through three reclose cycles. Believe it or not, after 15 years he apparently has no bad side affects.
Yet..
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
Suggest checking your state laws. For example, Alaska is pretty clear:
HV lines is anything over 750V
Overhead lines means above ground, energized, and not in "Iron Pipe" - pretty broad definition.
Have to stay 10 feet away or:
The operator (of the HV lines) is require to de-energize, or put up barriers. The outfit requesting the protective barriers is required to pay for the operator's work.
Just not putting up the required sign is up to $500 and up to 6 months in jail - per day
And if they screw up and have actual contact, the violator is liable for all the damage and all the liability of the operator/owner.

The following is the state law (reference):
www.labor.alaska.gov/lss/forms/electrical-stats-regs.pdf

Sec. 18.60.670. Prohibition against placement of equipment near electrical power lines and conductors.
A person individually or through an agent or employee may not
(1) place any type of tool, equipment, machinery, or material that is capable of lateral, vertical, or swinging motion, within 10 feet of a high voltage overhead electrical line or conductor;
(2) store, operate, erect, maintain, move, or transport tools, machinery, equipment, supplies, materials, apparatus, buildings, or other structures within 10 feet of a high voltage overhead electrical line or conductor.

Sec. 18.60.680. Placement of barriers for temporary work.
Before a person is going to temporarily engage in work or other activity in closer proximity to a high voltage line or conductor than is permitted by AS 18.60.670, the person shall immediately notify the operator or owner of the high voltage line or conductor of the work to be performed and make appropriate arrangements, with payment satisfactory to the operator, for the installation of temporary mechanical barriers, temporary deenergization and grounding of the conductors, or a temporary raising of the conductors. Costs incurred by an operator or owner of a high voltage line or conductor in providing barriers, deenergization, and grounding as specified in this section shall be paid by the person engaging in the work that requires these protective measures.

Sec. 18.60.695. Definitions.
In AS 18.60.670 - 18.60.695,
(1) "high voltage" means a voltage in excess of 750 volts between conductors or between any single conductor and the ground;
(2) "overhead lines or overhead conductors" means all bare or insulated electrical conductors installed aboveground except those that are de-energized and grounded or enclosed in iron pipe or other metal covering of equal strength.


And there has to be a Sign:
Sec. 18.60.675. Posting of warning sign before operation.

A person individually or through an agent or employee may not operate a crane, derrick, power shovel, drilling rig, hoisting equipment, or similar apparatus, any part of which is capable of vertical, lateral, or swinging motion, unless the operator or the operator's employer posts and maintains, in plain view of the operator, a durable warning sign legible at 12 feet that reads as follows: "It is unlawful to operate this equipment within 10 feet of high voltage lines."


And they even put a criminal penalty, civil liability on it:
Sec. 18.60.685. Criminal penalty; civil liability for damages.
(a) A person who violates AS 18.60.670 - 18.60.695 is guilty of a misdemeanor, and upon conviction is punishable by a fine of not more than $500, or by imprisonment for not more than six months, or by both.
(b) If a violation of AS 18.60.670 - 18.60.695 results in physical or electrical contact with an overhead high voltage line or conductor, the violator is liable to the owner or operator of the high voltage line or conductor for all damage to the facilities and for all liability incurred by the owner or operator as a result of the unlawful activities.
(c) Each day on which a person fails to post or maintain a sign as required by AS 18.60.675 constitutes a separate and additional violation.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
None of it’s pretty. I know a few older people with burns and missing limbs that I consider lucky. ...
Met a guy on the airplane a few years back - Pretty sophisticated knee, leg, foot. Had some electric stuff in the prosthetic - couldn't tell what it did. One hand/arm was twisted up, one side of his face was twisted.

He said he had been on his roof cleaning the chimney, and top of the brush pole hit a 13.8kV line. All he remembers is the feeling of being hit with a swarm of bees.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
I could of sworn there is working clearance tables in the nec for transmission lines...but it may be a old field manual, kind of a uglies, but also includes rigging rules and the such.
It’s in 70E, not the NEC. Hopefully they have corrected the typo, they were increasing the distance by one inch for every 10,000 volt increase if I remember correctly. That was about 15 years or so ago.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I knew a guy with only one limb left (left arm) after falling into 7200. He had many more health problems from it as well.

Roger
 

Besoeker3

Senior Member
Location
UK
I disagree. De-energizing is not enough.
Unless there's enough physical separation so there's NO chance of contact -- and you wouldn't be asking if that were the case -- the line should be de-energized, locked out & tagged out, tested by a lineman qualified to work at that voltage and wearing the appropriate personal-protective equipment, then clamped with shorting cables to assure the roofers' safety even if someone does inadvertently turn it back on.
Totally agree. We also would have had to a permit to work and an approved site safety passport. These were mandatory.
 

tommydh

Member
Location
baltimore,md
I disagree. De-energizing is not enough.
Unless there's enough physical separation so there's NO chance of contact -- and you wouldn't be asking if that were the case -- the line should be de-energized, locked out & tagged out, tested by a lineman qualified to work at that voltage and wearing the appropriate personal-protective equipment, then clamped with shorting cables to assure the roofers' safety even if someone does inadvertently turn it back on.
Just today the Safety headline at the plant I'm at referred to a 16 year old roofer that was adjusting his ladder and lost balance hitting an overhead line killing him. So every precaution must be taken not only to de-energize but to ensure it remains safe for the duration of work. So this means not only being Locked out and tagged by Electrical person but each member of roofing crew should have a lock on a box or multi clamp that only is removed when complete. Also sounds like a good time to have the cables inspected and/or tested to ensure the integrity of insulation.
 
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