Electrical Hazards Awareness Briefing

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Electrical Hazards Awareness Briefing

• Electrical Safety Hazard Awareness for
• Electrical Arc Welding and Cutting
• Module 3
• May 31, 2006

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Purpose

• Worker safety
• Raising your awareness of electrical hazards
  associated with arc welding and plasma
• Instructing you on how to recognize electrical
  hazards
• Providing ways to eliminate, remove and prevent
  electrical hazards in the workplace
• Emphasizing the extreme importance of observing
  all electrical safety requirements and practices

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Electric Arc Welding Hazard

• Arc Welding and Plasma cutting equipment produces
  controlled power arcs that can cause electrical
  shock if not properly operated and protected.
• Arc welding and plasma cutting is the discharge
  of electricity through combination of ionized air
  and vaporized conductor material.

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Welding Death in Aiken SC
On July 28, 2005, an experienced welding
supervisor died from cardiac arrhythmia due to
electrocution. According to the Aiken Standard
News, he inadvertently grounded out the welder
and sent electricity through himself instead of
the welding rod. It was a hot day and he was
sweaty according to reports. Reports indicated he
had been welding for years. Complacency and
working conditions may have played a role in this
fatality.
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Electrical Hazards Arc Welding

• A potentially dangerous open-circuit voltage
  exists between the electrode holder and work
  piece/ground it presents a hazard to the welder
  and those around him (normally gt50V but lt100V
  except for plasma arc - Plasma Arc machine
  potentials 200 to 400V).
• Voltage exists whenever power applied via POWER
  ON/OFF Switch.

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Welding Circuit Electrical Hazard
If you touch the welding electrode and ground or
the work lead, you become part of the welding
circuit and will receive a hazardous electrical
shock if you are not properly insulated from the
circuit. If you touch the work lead and an
ungrounded work piece, you may receive an
electrical shock. This is called a touch
potential because there may be a difference in
potential between the two contact points. (Note
It is common to find voltage on both the work
lead and electrode lead for some welding
equipment.)
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Electrical Hazard Arc Welding

• A SHOCK may occur when
• Equipment isn't properly grounded
• Direct contact is made with energized leads
• Contacting leads with moist/damp gloves,
  clothing, or floors.
• Environmental conditions such as wet or
  cramped/confined spaces - may make the likelihood
  of shock greater.
• Shock could throw a welder out of position or
  cause falls resulting in potential major injuries.

The avoidance of electrical shock is largely
within control of every welder. Electric shock
can kill! AC or DC welding has the power to
cause electrocution if electrode touches bare
skin (damp or wet gloves /or clothing) while you
are grounded.
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Electric Shock Injury Factors

• Amount of current conducted through your body.
• Resistance of the tissues
• Voltage or potential difference (electromotive
  force) applied primarily it is the OPEN CIRCUIT
  VOLTAGE of a welding or plasma arc machine
• Path of the current through your body
  (hand-to-hand or hand-to-elbow, etc.)
• Length of time you are subjected to the
  current.
• Type of current alternating (AC) direct
  current (DC).
• Your present physical state or condition (sick,
  pre-existing condition, wet, perspiring).
• Total area of skin contact with the welding
  circuit.

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Safe Practices-Rules

• Welders must comply with all safety
  precautions/instructions as found in site
  procedures and the manufacturers or owners
  manual prior to operating/servicing any welding
  equipment.
• OSHA (1910.254(d)(6)) states printed rules and
  instruction covering the operation of the
  equipment supplied by the manufacturer shall be
  strictly followed.
• READ, UNDERSTAND and FOLLOW ALL INSTRUCTIONS and
  LABELS.

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Safe Practices Grounding

• Connect the workpiece being welded and the frame
  or chassis to an approved electrical ground.
• Use building frame or other appropriate ground
  (Reference NEC Article 250)
• DO NOT use chains, wire ropes, crane hoists and
  elevators as ground.
• The work lead is not the ground lead. The work
  lead connects the work terminal on the power
  source (weld machine) to the workpiece it is
  the return path for the welding circuit.
• Use a separate lead to ground the workpiece.

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Electrical Safe Practices Grounding
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Electrical Safe Practices Grounding

• Voltage does exist between the electrode and work
  piece.
• Use a Ground Fault Circuit Interrupter (GFCI)
  such as receptacles in boxes, extension cords,
  etc. when using the auxiliary power from welding
  generators.

• Never ground to an electrical conduit or to a
  pipe carrying any gas or flammable liquid such as
  oil or fuel.
• Inspect ground connections regularly high
  impedance (resistance) connections and bare spots
  on cables increase possibility of electrical
  shock.

Ground Clamp Not Connected
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Grounding Method I
Ground Method I Bldg Ground to Work Lead
Terminal and to Weld Table
A complete grounding method consists of an AC/DC
power source, the electrode lead or cable, a work
lead attached to the work piece or table, and
separate ground wire/clamp (bare metal
connections) as close as practical to the area to
be welded.
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Grounding Method II
Ground Method II Bldg-Ground to Work Piece and
Work Lead to Work Piece OR both to Weld Table
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Safe Practices Cables

• Do not wrap cables carrying electric current
  around any part of your body!
• Do not use worn, damaged, undersized, or poorly
  spliced cables, welding gun cables, or torch
  cables.
• Make sure all connections are tight, clean (bare
  metal), and dry.
• Ground return cables must be at least the same
  size or larger than the work cable with good
  mechanical connections.

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Safe Practices Cables

• Excessive cable length can cause
• Equipment damage
• Increase the potential for worker injury
• Use leads of minimal length. If longer leads
  are occasionally needed, cable lengths should be
  added using in-line (jacked) connections.

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Safe Practices Protecting Others

• Welders must protect themselves and OTHERS in the
  vicinity of welding operations from electrical
  shock.
• Turn OFF welding machines when leaving for
  appreciable/extended periods of time. (OSHA)
• YOU MUST prevent the general population from
  coming in contact with ENERGIZED ELECTRODES
  both leads are electrically energized/HOT!

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Safe Practices-Perspiration

• Perspiration dramatically lowers skin resistance
  allowing greater electrical current to flow in
  your body.
• During periods of high heat/humidity, you must
  use dry hole-free insulated (leather) gloves.
  Change gloves as necessary to maintain dryness.

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Safe Practices Electrode Holders

• DO NOT use damaged electrode holders or defective
  welding cables.
• Poor connections/bare spots on cables increase
  shock probability.
• DO NOT touch Electrodes or welding wire with bare
  hands.

Insulation Missing/Damaged
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Safe Practices Electrode Holders

• Electrode lead/holder or welding gun should never
  be held/placed under the armpit.

Electrical Burn/Injury
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Safe Practices Electrode Holders

• Never dip the holder into water to cool it or lay
  it on conductive/work surface.
• All metal parts touching the electrode
  (GMAW/FCAW) are energized when the power is on
  wire, wire reel, drive rolls, etc .
• Do not allow holder or electrode to contact/touch
  another person.

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Safe Practices Electrode Holders

• In order to prevent damage to the insulators on
  the electrode lead, the electrode should be
  discarded when all but approximately 2 inches
  from the electrode holder has been consumed.
  Attempting to consume the electrode all way up to
  the electrode holder will burn away the
  insulators and increase the potential for
  electric shock. The electrode holder will be
  damaged by exposure to extreme heat.

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Safe Practices Electrode Holders

• Work and electrode leads should be inspected.
  Flexibility of the leads should be uniform stiff
  places in the leads indicate fusing of the copper
  filaments, which probably has been caused by a
  current leakage.

Normal Multi-strand copper cable/wire
Multi-strand copper cable/wire fused
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Safe Practices- Electrodes
OSHA Electrode holders when not in use shall be
so placed that they cannot make electrical
contact with persons, conducting objects, fuel or
compressed gas tanks.
Establish the controls and measures
necessary to create safety working conditions
including barricading of work area and proper
posting to protect personnel in area of
welding/plasma arc operations.
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Safe Practices- PPE

• Always wear dry hole-free insulating (refers to
  both protection from heat, sparks, and electrical
  insulating properties) gloves to protect against
  or reduce electric shock.
• Wear rubber-soled high-top shoes

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Safe Practices- PPE
Use insulating layer, such as dry board or rubber
mat, for protection from conductive surfaces.
Whats wrong with this picture?? Look at his
SHOES!
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Safe Practices- Maintenance

• Discontinue use of welding equipment or cables
  that are defective. Report equipment defect or
  safety hazard to your supervisor.
• Inspect welding cables and connectors for wear
  and damage.
• Equipment modifications should only be performed
  by a qualified service technician