Where Do You Stand on the Left-Hand Rule
Dave Smith has been an Industrial Maintenance Electrician since 1975. He has taught maintenance, troubleshooting and safety courses to thousands of electricians in mines, mills, refineries, factories, plants, power stations and offshore platforms throughout North America and the Middle East. Dave is a hands-on guy and teache...
June/July 2010
By Dave Smith
When you are switching a piece of electrical; equipment with the operating
handle on the right-hand side, where should you stand to operate that piece of
equipment? "This question was asked at a recent conference----it
never seems to go away.
I have been an electrician since 1975. The Left--Hand Rule was drilled into me
and every other apprentice going back to 1879 when Thomas Edison turned the
power on. We were drilled and grilled to stand to the right of the equipment,
grab the handle with our left hand, face away and very forcibly operate it
either On or Off in a Swift, decisive movement, with no hesitation.
With the advent of arc flash awareness, this rule is being challenged by some
who suggest it is safer to reach across the front of that equipment----placing
your body directly in front of it---and operate that handle with your right
hand. The rationale is this: were there an arc flash, then the metal door would
protect you.
I have a few things to say about this line of thinking. With the left--Hand
Rule, we have 131 years of empirical evidence showing that it works; we don' t
have nearly the same amount of evidence with this new thinking. I have logged
over 12'000 hours in classrooms---most of them teaching electrical safety----and
have met numerous students that have had doors blow past, or over, them. When
they followed the Left--Hand Rule, Their bodies were not hurt. Those who got
caught by a door, however, always suffered major damage.
Secondly, let's say the door protects you from the blast. What research has
been done to evaluate the force of that same door bursting its clasps and
propelling your arm backward with all of its unspent force? Would it merely
destroy your rotator cuff and shoulder ligaments, or rip your arm right out of
its socket?
Six years ago, an operator pushed a 480V Start button on a 30--amp contractor
with a dead short 40 Ft away in a motor. When he hit the Start button with his
right hand, the door blew open, driving his hand leftward into a pipe and
permanently damaging his arm. He'll never throw a ball again.
Thirdly, this thinking ignores that fact that door can get ripped off of
hinges. My very first experience with this was with a hospital electrician in Calgary in 1981. He threw
on a 600--volt star--delta starter with his right hand and, when it came into
the first stage, he could hear something sizzling. He immediately started
moving out of the way, but it exploded when it hit the second stage, ripping
the door clear off the hinges. His left hand was caught by the flying door,
breaking his lower arm and hand. The door bent an iron railing about 10 Ft
away, and the explosion was heard on the 5th floor! There was enough force in
that blast that, had he been standing directly in front, it would have caved in
his entire chest and completely crushed the bones in his face.
Recently, I was standing 20 Ft from the secondary of a utility
transformer...in front of a 30--year old, 1600--amp disconnect that had
not been operated
in eight years. This switch was old and ugly. If you feel like putting your arm
across to operate that disconnect, I honor your courage: you definitely have
more of it than me.
Were I sill an electrical foremen, I would go ballistic were I to see one of my
crew operating that piece of equipment in that fashion. My son is a journeyman,
and I hope he never reaches across such a piece of equipment. The explosive
force would be thousands of horsepower!
The reality is this: there are no simple answers to complex questions. When you
operate any type of switch, recognize there is nothing more than a thin metal
door between you and as much energy as the system can supply. So it makes sense
to do this in the safest manner possible, or you'll get, permanently
disabled....maybe worse.
We never intend nor expect something to blow up, but electrical systems are
subject to water infiltration, environmental contamination, incipient failure,
and things that creep, crawl and slither. Additionally, you have no idea what
damage may have occurred years ago to a critical part of the insulating
system. We always accept in blind faith chat our equipment is in good shape
until the day it blows.
There certainly are instances where you are forced to put your body at risk
but, if it is at all avoidable, then don't do it. When the operating mechanism
is in the centre or to the hinged side, the please stay on the hinged side.
When it is opposite the hinged side, then follow the Left--Hand Rule and
protect yourself from an arc flash with the right PPE (personal
protective equipment). Put on your rubber gloves and leathers (they give great
arc flash protection), protect yourself with multiple layers
of FR clothing, and put on your face shield and face the switch. Take a deep
breath, close your eyes, and move that handle with
all the muscle you can muster and no part of your body in front of that door.
Should a small explosion occur, nothing will happen; a larger one will bulge
the door; larger one yet will blow the door open and, sometimes, rip the door
right off of its hinges. Once you witness the aftermath of such an event, you
would never advise anyone to put their body in front of a switch. If you choose
to do it, then more power to you. For my part, I'll continue to follow the
Left--Hand Rule that has proved itself time and time again over the last 131
years. Until next time, be ready, be careful and be safe.
