Exposed Live Parts – An  Engineer’s Concerned Position

 

In the United States, according to the Census of Fatal Occupational Injuries, between 1992 and 1999, there were more than 2500 deaths. At least 648 deaths, more than 25% of the fatalities, occurred because of contact with electrical components of power distribution other than power lines.

 

The National Electrical Code allows live parts to be exposed provided the area is only accessible to qualified personnel:

 

110.27 Guarding of Live Parts

(A) Live Parts Guarded Against Accidental Contact. Except as elsewhere required or permitted by this Code, live parts of electrical equipment operating at 50 Volts or more shall be guarded against accidental contact by approved enclosures or by any of the following means:

(1) By location in a room, vault, or similar enclosure that is accessible only to qualified persons.

(2) By suitable permanent, substantial partitions or screens arranged so that only qualified persons have access to the space within reach of the live parts. Any openings in such partitions or screens shall be sized and located so that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them.

(3) By location on a suitable balcony, gallery, or platform elevated and arranged so as to exclude unqualified persons.

(4)  By elevation of 2.5 m (8 ft) or more above the floor or other working surface.

 

III. Over 600 Volts, Nominal

 

110.34 Work Space and Guarding.

(C) Locked Rooms or Enclosures. The entrance to all buildings, vaults, rooms, or enclosures containing exposed live parts or exposed conductors operating at over 600 volts, nominal, shall be kept locked unless such entrances are under the observation of a qualified person at all times.

Where the voltage exceeds 600 volts, nominal, permanent and conspicuous warning signs shall be provided, reading as follows:

DANGER — HIGH VOLTAGE — KEEP OUT

 

Construction workers (Qualified personnel?) are dying at the rate of 2.1 deaths per 100,000 persons per year. Requiring all live parts to be enclosed up to a height of  84” or higher could prevent a significant number of these deaths.  

 

Accidental Electrocutions aren’t limited to the workplace. In February, a 4-year old in Houston, Texas crawled into an unlocked transformer. She and a friend were injured. Her family will collect millions of dollars according to settlement information.

 

In New Orleans, in early March, a street person who had been living in a transformer vault was electrocuted.

 

February 13, 2007, a college freshman wandered into a transformer vault and was electrocuted.

 

The three events above took place within the span of less than one month of this year. Locks are insufficient protection. People are imperfect. Locks are left unlocked or fail or are removed by vandals. Unlocked spaces attract children, teenagers and those seeking warmth and shelter. Electrical parts need to be shielded.

 

All  installations covered by the NEC should require equipment located under a height of 84” to be metal enclosed and designed so that foreign objects inserted through openings will be deflected. No exception should be made for areas accessible to qualified persons only. There is no such area and there is no such person.

 

According to a report on electrical incidents in Canada by Mike Reiser, P. Eng., more deaths occurred due to accidental contact with electrical equipment than from contact with live equipment being repaired or from faulty equipment.

 

How many lives could be saved by changing the code? The statistics from any one survey are inappropriate to determine the number, but if the rates are comparable between different surveys in Canada and the US, then at least 40 unimportant deaths could be prevented each year.

 

Did you just respond with outrage? I hope so. Deaths of electrical workers are discounted because they could have known better; should have known better. An inherently high risk condition is allowed to continue to exist because with education, the worker should be able to survive working in adverse conditions. If an electrical worker violates an OSHA rule, then his family isn’t going to collect three million dollars. The newspapers aren’t going to run coverage every day for weeks. It won’t hit CNN. His death is unimportant. So death after death after death continues to occur because the rules are inappropriate for the situation.

 

The NEC rules need to be changed in order to protect little girls, and college students, and vagrants. The NEC frequently changes in order to protect such people. But, the NEC also needs to change in order to protect the lives of hundreds of diligent, hard-working individuals who work with electricity on a daily basis.

 

Deborah J. Mann, PE