Electrical - intelliquestmedia.com · – 1910.137 & 1926.97 for Electrical Protective Equipment Electrical OSHA 29 CFR 1910.269 Workplace Safety • Electric Power Generation,

9/30/2013

1

ElectricalW o r k p l a c e S a f e t y

1910.269 Proposed Changes

Hugh Hoagland

ElectricalWorkplace SafetyElectrical Standards

OSHA 29 CFR 1910 .331-.335

.147

.137

.269

1926 .950

NFPA 70E –2012 (under revision for 2015)

ANSI/IEEE C2 -

NESC –2012 (under revision for 2017)

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ElectricalWorkplace Safety

Itishardtopredictthefuture,

especiallybeforeithappens.– MarkTwain

ElectricalWorkplace Safety1910.269 Changes

In January 2013 OSHA’s agenda indicated they would publish the new standard in March.

OSHA source indicates that it is on the OMB desk and would likely be out in two weeks to two months

Here are my predictions based on the June 2005 document and IEEE 516 and NESC 2007/2012.

Prepare for these since these are consensus standards but if your company is a “OSHA minimum” company (whatever that is), you might want to wait until the standard is published

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ElectricalWorkplace SafetyCost/Benefit Analysis & Scope

• OSHA cites a $34m estimated annual cost

against$135m in annual benefits

• Proposed Revision June 15, 2005:– OSHA 29 CFR 1910.269 (Subpart R) and

– 1926, Subpart V (.950-.968)

– 1910.137 & 1926.97 for Electrical Protective Equipment

ElectricalWorkplace SafetyOSHA 29 CFR 1910.269

• Electric Power Generation, Transmission, and Distribution

– Final Rule –January 31, 1994

• Proposed Revision Federal Register

– June 15, 2005

• Anticipated Final Rule May 2013

– Scheduled for March 2013 in Jan OSHA Agenda

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ElectricalWorkplace SafetyOSHA Unified Agenda

http://www.reginfo.gov/public/do/eAgendaViewRule?pubId=201210&RIN=1218-AB67

ElectricalWorkplace SafetyDownload the Proposed Text

http://www.osha.gov/FedReg_osha_pdf/FED20050615.pdf

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ElectricalWorkplace SafetyMajor Changes

(a)(2) Training

(a)(4) Contractors

(i) Host…

(ii) Contract…

(c) Job Briefing

(e) Enclosed Spaces

(g)(2) Fall Protection

(l) Working on or near exposed energized parts

(m) Deenergizing lines and equipment for employee protection

(n) Grounding for the protection of employees

(p) Mechanical Equipment

(t) Underground electrical installations

(x) Definitions


• Updates to latest consensus standards

– NFPA 70E

– NESC

– ASTM

– IEEE

• Clarifying the Standard Changes

• Accident Cause Changes

Thrust of the Changes

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ElectricalWorkplace Safety(a)(2) Training Changes $1.2 million

(i) All employees shall be trained:

(A) Employees shall be trained in and familiar with:

safety-related work practices, safety procedures, and other safety requirements …that pertain to their …job assignments.

(B) Employees shall also be trained in and familiar with:any other safety practices…that are related to their work and are necessary for their safety.

(C) The degree of training shall be determined by the risk to the employee for the task involved.

(ii) Qualified employees shall also be trained and competent in:

(v) The recognition of electrical hazards to which the employee may be exposed and the skills and techniques necessary to control or avoid those hazards.

ElectricalWorkplace SafetyTraining is More Than Telling

The existing requirement for employers to certify that employees have been trained

would be replaced with a requirement for employers to determine that employees have demonstrated proficiency in the work practices involved

Plus a new note would be added to clarify how training received in a previous job would satisfy the training requirements.

– § 1910.269(a)(2)(vii) ---- § 1926.950(b)(7)

Auditing is also clarified (similar to NESC/NFPA 70E)

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ElectricalWorkplace SafetySupervision & Annual Inspection

(3) Supervision and annual inspection. The employer shall determine, through regular supervision and through inspections conducted on at least an annual basis, that each employee is complying with the safety related work practices required by this subpart.

(4) Additional training. An employee shall receive additional training (or retraining) under any of the following conditions:

(i) If the supervision or annual inspections required by paragraph (b)(3) of this section indicate that the employee is not complying with the safety-related work practices required by this subpart, or

(ii) If new technology, new types of equipment, or changes in procedures necessitate the use of safety-related work practices that are different from those which the employee would normally use, or

(iii) If he or she must employ safety related work practices that are not normally used during his or her regular job duties.

Using ANSI Z10 for continuous improvement of electrical safety is recommended by NFPA 70E and would help comply with this part of OSHA.

ElectricalWorkplace SafetyContract Employer(CE)/Host Employer(HE)

• Newly defined terms

• Similar Language to NFPA 70E

• (i) HE responsibilities. – The host employer shall inform CE’s of:

– Known hazards that are related to the CE's work,

– Information about the HE's installation

• The HE shall report observed CE-related violations of this section to the CE.

• CE responsibilities.– Shall ensure that each of his or her employees is instructed

in the hazards communicated to the contract employer by the host employer.

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ElectricalWorkplace SafetyMore CE/HE Relationship Regulation

• The CE shall ensure that each employee follows the work practices required and safety-related work rules required by the HE.– The CE shall advise the HE of:

• Any unique hazards presented by the CE's work,

• Any unanticipated hazards found during the CE's work that the HE did not mention, and

• The measures the CE took to correct any violations reported by the HE … to prevent such violations from recurring in the future.

• EEI has argued that this provision is without legal authority so this could be dropped but is still in NFPA 70E.

ElectricalWorkplace SafetySubstation Changes/Clarifications

• Fences must be grounded

• Gates of unattended must be locked

• Permanent guarding required

• Unqualified persons are also prohibited from areas containing live parts operating at more than 600 volts, unless the live parts are completely enclosed in metal enclosures or are installed at an elevation of at least 8 feet, 6 inches. The metal enclosures must be grounded, and the minimum height increases with increasing voltage.

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Arc-Rated Clothing § 1910.269(l)(6) [Revised] and (12) [New]. § 1926.960(f) and (g)

1926.960(g) Clothing.

(1) Hazard assessment

The employer shall assess the workplace to determine if each employee is exposed to hazards from flames or from electric arcs.

(2) Estimate of available heat energy

For each employee exposed to hazards from electric arcs, the employer shall make a reasonable estimate of the maximum available heat energy to which the employee would be exposed.

(3) Prohibited clothing.

The employer shall ensure that each employee who is exposed to hazards from electric arcs does not wear clothing that could melt onto his or her skin or that could ignite and continue to burn when exposed to the heat energy estimated under paragraph (g)(2) of this section.


HRC 4 – 40 cal/cm²

Either

4,8,12 cal/cm²

or

40 or 60 cal/cm² Suit

HRC 2 – 8 cal/cm²

Simplified and Fool-Proof PPE Program

Arc-Rated PPE

NESC/NFPA 70E Simplified PPE programs –Use the Two-Category Approach

(Annex H.2 or NESC options)

18

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Reducing the Arc Hazard Proposed § 1926.965

Arc blast blanketsCan totally contain energy.

ASTM F2676

Arc equipment shields attach to hot stick/shotgun stick or racking screw and cut energy by 50%.

ASTM F2522

Electrical Hazards – Arc Flash 19

ElectricalWorkplace SafetyShoes Recommended & Required…

EH Rated(recommended for dry conditions)

• Lower Voltage, Lower Risk Exposure

• 130.7(C)(8)Secondary Protection Only

• (ASTM F2413 or CAN/CSA Z195, 14kV, Test Soles only)

• Wet conditions (i.e. DC Battery Rooms, electrolytic cell rooms)

• Required “equipment grounding near power lines” NFPA 70E 130.8(F)(3)

• Common for walking downed powerlines.

• High Voltage, High Risk Exposure

• (ASTM F1117, Test to ASTM F1116 20kV, Tested wet on whole shoe/boot)

Shock » Protection » PPE

DI Rated(required when…)

20

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Energy Calculations Appendix F to § 1910.269 [New] & Appendix F to Subpart V

Note 1: Appendix F…provides guidance on the estimation of available heat energy.

Standard for Electrical Safety Requirements for Employee Workplaces, NFPA 70E-2004, Annex D, ``Sample Calculation of Flash Protection Boundary.''

Doughty, R.L., Neal, T.E., and Floyd II, H.L., ``Predicting Incident Energy to Better Manage the Electric Arc Hazard on 600 V Power Distribution Systems,'' Record of Conference Papers IEEEIAS 45th Annual Petroleum and Chemical Industry Conference, September 28-30, 1998.

Guide for Performing Arc Flash Hazard Calculations, IEEE 1584-2002.

Heat Flux Calculator, a free software program created by Alan Privette (widely available on the Internet). (factors required for 3Phase & Box)

ARCPRO, a commercially available software program developed by Kinectrics, Toronto, ON, CA. (factors required for 3Phase & Box)

The employer should require each exposed employee to have no more than 10 percent of his or her body unprotected.

ElectricalWorkplace SafetyFlame Resistant Clothing Minimum

(4) Flame-resistant clothing. The employer shall ensure that an employee wears clothing that is flame resistant under any of the following conditions:

(i) The employee is subject to contact with energized circuit parts operating at more than 600 volts,

This could go away. NESC 2007 said 1000V, 2012 no exclusion.

(ii) The employee’s clothing could be ignited by flammable material in the work area that could be ignited by an electric arc, or

(iii) The employee’s clothing could be ignited by molten metal or electric arcs from faulted conductors in the work area.

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ElectricalWorkplace SafetyFlame Resistant Clothing Rating

(5) Clothing rating. The employer shall ensure that each employee who is exposed to hazards from electric arcs wears clothing with an arc rating greater than or equal to the heat energy estimated under paragraph (g)(2) of this section.

ElectricalWorkplace SafetyTagOut vs. LockOut

• Utilities have long had tagout vs. lockout issues with the law and this continues.

• Expect OSHA to continue to push for lockout especially in power plants.

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ElectricalWorkplace SafetyJob Briefing

(1) Before each job. (i) provide the employee in charge of the job with available

information necessary to perform the job safely.

(ii) ensure that the “employee in charge” conducts a job briefing … with the employees involved before they start each job.

(2) Subjects to be covered. The briefing shall cover at least the following subjects:

hazards associated with the job, work procedures, special precautions, energy source controls, and PPE requirements.

(3) Number of briefings. (i) At least one job briefing shall be conducted before the start of

the first job of each day or shift.

(ii) Additional job briefings shall be held if significant changes, which might affect the safety of the employees, occur during the course of the work.

ElectricalWorkplace SafetyJob Briefing

(4) Extent of briefing. (i) A brief discussion is satisfactory if the work involved is

routine and if the employees, by virtue of training and experience, can reasonably be expected to recognize and avoid the hazards involved in the job.

(ii)A more extensive discussion shall be conducted:(A)If the work is complicated or particularly hazardous, or

(B)If the employee cannot be expected to recognize and avoid the hazards involved in the job.

Note to paragraph (c)(4) of this section: The briefing must always touch on all the subjects listed in paragraph (c)(2) of this section.

(5) Working alone. An employee working alone need not conduct a job briefing.

However, the employer shall ensure that the tasks to be performed are planned as if a briefing were required.

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Safety-Related Work Practices

• Timing – Before starting each job

– Before any change in job scope

• Type– Field

– Formal

• Outline (Annex I)– Identify

– Ask

– Check

– Know

– Think

– Prepare for emergencies

Job Briefing

NFPA 70E 110.3(G)

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ElectricalWorkplace SafetyNew Definition: Entry

Entry (as used in paragraph (e) of this section).

The action by which a person passes through an opening into an enclosed space. Entry includes ensuing work activities in that space and is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space.

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Enclosed Space Changes More Like Confined Space

• Add a definition of “entry” and remove associated note

• Requirement to provide an attendant if there is reason to believe that a hazard exists

• Require test instruments to have an accuracy of ±10 percent of what you are measuring

• Require employer to demonstrate that ventilation is sufficient

• Will require sufficient lighting never addressed for daytime

ElectricalWorkplace SafetyFall Protection

• Clarify that fall arrest equipment used in aerial lifts must meet Subpart M of the construction standards (OSHA 1926)

• Update the requirements for work positioning equipment (through a reference to Subpart V) (also OSHA 1926)

• Possible requirement to decrease fall distance from 6 ft. to 2 ft.

• Will require ASTM F887 which includes arc testing of harness

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Site Specific Considerations

Make sure a fall protection assessment is completed and the appropriate safety precautions in place before you work at an elevated level.

Fall Protection

31

ElectricalWorkplace SafetyWorking on or Near Energized Parts

(2)(i) The employee is insulated from the energized part

– Employee is insulated from the energized part (insulating gloves or insulating gloves and sleeves

– Provided that the employee has control of the part in a manner sufficient to prevent exposure to uninsulated portions of the body)

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ElectricalWorkplace SafetyWorking on or Near Energized Parts

(3) Type of insulation.If the employee is to be insulated from energized parts by the use of insulating gloves…insulating sleeves shall also be used

Some exceptions

(4) Working position. (i) The employer shall ensure that each employee, …

works in a position from which a slip or shock will not bring the employee's body into contact with exposed, uninsulated parts energized at a potential different from the employee.

ElectricalWorkplace Safety(6) Conductive Articles

– When work is performed within reaching distance of exposed energized parts of equipment, the employer shall ensure that each employee removes or renders nonconductive all exposed conductive articles, such as key or watch chains, rings, or wrist watches or bands, unless such articles do not increase the hazards associated with contact with the energized parts.

This is less restrictive than NFPA 70E

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ElectricalWorkplace SafetyDo Not Wear Conductive Articles

Arc-Rated PPE – Non-Conductive 35

ElectricalWorkplace SafetyUnderground Installations

• Paragraphs (3), (7), and (8) have been revised and expanded for clarity

• Apply all provisions to manholes and underground vaults

• Added requirement to de-energize cables or protect employees if the work could cause a fault

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ElectricalWorkplace SafetyMAD Distances

• NESC has had the term MAD since early 1900’s

• OSHA adopted the term in 1910.269

• IEEE 516 IEEE Guide for Maintenance Methods on Energized Power Lines (Phase to Ground)

– MAID – Minimum air insulation distance

– MTID – Minimum tool insulation distance

– MAD – Minimum approach distance

– MAD for tools – MAD with tool in air gap

– MHAD – Minimum helicopter approach distance

ElectricalWorkplace SafetyTwo Types Of Boundaries: Shock & Arc

Protection Strategies

Arc Flash Boundary

Shock Protection Boundaries EnergySource

Limited “Public Safety Boundary” Person in Charge Boundary: NESC 421.B.1 OSHA 1910.333 & .269 (w)(6)(ii)

Restricted “Shock PPE Boundary”Minimum ApproachDistances (MAD) NESC 431

Arc Flash At 2 cal/cm² PPE is Required: NESC 410.A.3

NFPA 70E NESC

38

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Phase-to-ground

Graph courtesy Jim Tomaseski, International IBEW Safety Director


New Class of Rubber Gloves (Voltage Rated Gloves)

• Section 1910.137 would be revised to include Class 00 rubber insulating gloves.

• Class 0 was all that was mentioned in previous versions.

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Ignition Limits on Voltage-Rated (VR) Gloves

Arc-Rated PPE – Gloves

53.5

41.9

31.2 30.4

21.4

0

10

20

30

40

50

60

Black Blue Yellow Red NaturalRubber

50% Ignition

Tests conducted on Salisbury gloves.

31 31.2

17.4

22.1

0

5

10

15

20

25

30

35

Black0.7mm

Blue0.7mm

Blue0.5mm

Orange0.65mm

50% Ignition

Class 00 Rubber GloveResults (cal/cm²)

Best Practice Class O Blue or Black

Class 0 Rubber Glove Results (cal/cm²)

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ElectricalWorkplace SafetyNew Arc Rated Glove Standards

• ASTM Standard will not require testing of Rubber Insulating Gloves or Leather Protectors– Most mfg. have already tested and may label even though

they are excluded from the standard in a compromise to get a standard.

– Non protector gloves and arc flash work gloves can be rated when ASTM releases the standard.

• IEC Standard began last month and will be unlikely to exclude rubber and leather.

• New Protector Glove standard will begin next cycle in ASTM and may produce more comfortable protector gloves. – OSHA does not preclude other protector gloves today.

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ElectricalWorkplace SafetyQuestions Asked of OSHA April 2013

What is the potential date now?

Any time now. OMB asked for another analysis -- could be in as soon as 2 weeks to 2 months. Likely faster since analysis was not over a controversial issue. In January, March looked very doable. Things change.

What will be the compliance time?

90-120 day, training and clothing minimum.

What are the effects on the 1910 non-269 world?

Mainly the addition of 00 gloves and removal of EH shoes as protection while still recommended. They save lives but you only know if they don’t work.

Tree trimming will change substantially in regulations to prevent deaths.

NFPA 70E & NESC compliant companies will find nothing new but agreement.

ElectricalWorkplace SafetyQuestions Asked of OSHA April 2013

How much has the auditing been focused on?

This is not focused on in citations but can be used effectively in defense.

Leading indicators vs. lagging indicators.

What about proficiency? Is that only for 269?

Definitely not. Qualified depends on the job duty and it really means proficient FOR THE TASK.

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ElectricalWorkplace SafetyBiggest Impacts

• Construction (1926) and Maintenance (1910) will be harmonized so compliance will be simplified.

– Many companies followed the more restrictive anyway.

– Different policies for different work will disappear.

• Arc Rated Clothing will be law for Generation, Transmission and Distribution work (LV and HV)

• EH shoes will be eliminated from OSHA language in 1910.136 to eliminate the possibility of people believing that EH shoes remove the need for rubber gloves, blankets or sleeves.

– This could be interpreted that they are unhelpful but this is not the case. NFPA 70E just added them as recommended for dry environments.

• DI shoes will still be needed if you have step potential

– This is the NFPA 70E language anyway but most don’t follow this requirement.

• Locking snap hooks on positioning devices (Most already made this way in anticipation)

• Arc Tested Harnesses ASTM F887-04 or later listed as required.


Questions? Want More Information?


www.e-hazard.com Email: [email protected]

Phone: (502) 716-7073

For a FREE* copy of our newsletter:

Text: “Newsletter” withyour e-mail address to:

925-Arc-Wear(925-272-9327)

Clothing in Arc Flash

Four Types of Arc Exposure and the Effect of Moisture on

Garment Appearance After an Arc Event

Hugh HoaglandMikhail GolovkovClaude Maurice

Phillip Clark

2013 IEEE, IAS Electrical Safety Workshop 1

4 Types of Arc Exposure

2

Tracking Arc

• Plasma next to body• Can cause clothing ignition

in an electrical contact• Usually at higher voltages

4. Open Air Arc

• Mostly radiant energy

1.

Arc-in-a-Box

• Mostly convective energy

3. Ejected Arc

• Mostly arc plasma• Convection at short

distance• Radiant further away

2.

2013 IEEE, IAS Electrical Safety Workshop

Radiant Energy Results from Open Air Arc Event

3

Open Air Radiated Arc with Convection

Open Air Arc1.

2013 IEEE, IAS Electrical Safety Workshop

Open Air Arc


Mostly Arc Plasma & Convection

5

Ejected Arc with Shield & without Shield

Ejected Arc2.

Convective Arc Energy is Forced Out Through an Opening (arc-in-a-box)

6Arc-in-a-Box 3.

Arc-in-Box from disconnect

Arc-in-a-Box


Most Common at >4160V & in Line or Substation Work

8

Tracking Arc 4.

Tracking on Sweat


2500V through sweat across wire with 8 inch gap

Tracking or Pop-Out Arc


7500V 8kA with small wire to start arcArc stays in clothing for 2 cycles then moves

Arc Blankets: Totally block up to kA/cycle limit


Arc shields block all plasma & >50% of total energy


Water Effect on Arc Exposures


Dry T-shirt with Tracking Arc Underneath

Wet Arc-Rated T-shirtwith Tracking Arc

Just Add Water

0

10

20

30

40

Dry/Dry Dry/Wet Wet/WetATPV 24 18 12.6EBT 23 24 35.6

Cal/cm2


Layer 2 (Brown)

5.4 oz/yd² (183 g/m²) Jersey Knit

75%15%10%

ModacrylicCottonNylon

AAD: 5.8 oz/yd² (197 g/m²)

Layer 1 (Med Blue)

2x1 Twill80%15%

5%

ModacrylicCottonPara-Aramid

AAD: 7.0 oz/yd² (237 g/m²)

AAD = Actual Areal Density

Less Burn Protection, Increased Fabric Integrity

Recommendations

• Choose arc rated PPE for all common electrical work

• Choose arc rated undergarments for higher voltage work– especially for upper torso


Design/Installation Considerations

• Recommend changes to NEC – Require disconnects to be placed for safe operation

from the side (not against a wall so worker must operate from front).

• Design >480V equipment so it can be operated from a safe side/zone

• Mark a safe zone for equipment operation when possible.


Work Practice Considerations

• Standing to side of equipment

• Use non-ignitable clothing in all work situations – especially with voltages greater than 1000V

• Use properly installed arc flash blankets – Rated for the fault current and clearing time which

meet ASTM F2676

• Use arc deflecting shields to shunt all plasma and up to 50% of the radiated & convective energy in an arc flash event when arc shields can be used


Questions?

Hugh Hoagland

502-333-0510

[email protected]

Mikhail Golovkov

502-333-0510

[email protected]

Claude Maurice

416-207-6350

[email protected]


Arc-Rated PPE & Contamination Study

Hugh Hoagland, Mikhail Golovkov,

Rob Pailing, Lionel Smith,Cecil Burton,

Claude Maurice

The real thing

ASTM F1959 Arc Rating

ASTM F1959 Adapted for Contamination Study

• The standard measures energy on a panel.

• We began with the base and wet ratings.


We drew a specific area

which covered the

calorimeters for the

contamination area.


Next we measured the mass of the

contaminants placed in each

area for the test to have

mass per unit area.


• Then we tested each contaminant.

• Some like transformer oil would continue to burn if we reached the ignition temperature.

• Here panel A ignites, the other two do not ignite.

• Each panel records the temperature rise and we compare this to the Stoll curve.

• In this exposure, panel A which ignited would have caused 2nd and 3rd degree burns on part of the body.


Last we did statistical

analysis of the data points to

predict the ATPV of the fabric with

contamination.


The Baseline: Wet & Dry Fabric

10.4

5.5

0

2

4

6

8

10

12

Dry Fabric Wet Fabric

Baseline Protection cal/cm²

The wet fabric was worst case scenario 2X weight of the dry. We soaked and wrung out the excess only. VERY wet.

Wet Contaminants cal/cm²

5.1

75.9

11.3

13

0

2

4

6

8

10

12

14

FloculentSlime

Grease HydaulicOil

CaOHSlurry

WetCement

Wet Contaminants

Dry Fabric 10.6 cal

Wet Fabric 5.5 cal

Diesel & Transformer oil ignited causing greater burns.Grease, hydraulic oil did not ignite less than 11 cal/cm² but did lower protection . All hydrocarbons will ignite causing greater burn than their thermal conduction reflects here.

Dry Contaminants cal/cm²

10.6

12.9

11.5 11.5

0

2

4

6

8

10

12

14

Carbon Dust Dry Cement Dry Lime PalladiumDust

Dry Contaminants

Dry Fabric 10.6 cal

Wet Fabric 5.5 cal

Summary Graph

Die

sel

fuel

Flo

ccu

len

t S

limes

Wat

er

Hyd

rau

lic o

il

Gre

ase

Tran

sfo

rmer

oil

Bas

e ra

tin

g

Car

bo

n d

ust

Slu

rry

Pal

lad

ium

du

st

Dry

lim

e

Dry

cem

ent

Wet

cem

ent

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

Rel

ativ

e R

atin

g (

to b

ase

rati

ng

)

Contaminants

Liquids

Solids and heavy saturatedmixes

Reduction in protective properties

Arc Rating Conclusions• Hydrocarbons can ignite at some level.

• Water/sweat does decrease protection but does not increase risk of ignition.

• Mixes of contaminants did not provide the negative consequences thought possible.

• Small percentages of hydrocarbons mixed with other non-flammable contaminants were not as dangerous as the pure contaminants.

Glove Testing 4 cal/cm²




8 cal/cm² shot

Carbon & Dry Lime

Carbon and Dry Lime

Commercial & Home Laundry

Diesel Fuel

Flocculent Slime & Grease

Nickel & Palladium

Nickel & Palladium

Diesel dirt vs Diesel & Grease light/heavy

Dirty Coveralls

Method of Areal Resistance Measurement: two electrodes at contaminated area edges, 5 kV DC megger as a voltage source

2 inch

12 inch

Electrical Conductivity

Conductivity and arc ratingContaminant

Areal Resistance Change cal/cm²

Wet Dry Wet Dry

Cement 15.6X103 Ohm >10X109 Ohm +2.6 (25%) + 2.5 (25%)

Flocculent Slimes (86-91)X103 Ohm - 5.3 (50%)

Slurry (44-54)X103 Ohm +0.9 (10%)

Grease (4.2-4.4)X109 Ohm -3.4 (35%)

Sweat <10X103 Ohm - 4.9 (50%)

Palladium Dust (6.7-9.0)X109 Ohm + 0.9 (10%)

Carbon (7-10)X109 Ohm +0.2 (2%)

Dry Lime >10X109 Ohm +1.1 (10%)

Transformer Oil >10X109 Ohm -3.2 (30%)

Hydraulic Oil 6.8X109 Ohm - 4.5 (45%)

Dry Contaminants on log Ohms

1

10

100

1000

10000

100000

1000000

10000000

00000000

1E+09

1E+10

Cement PalladiumDust

Carbon Lime

Saline

Dry Contaminants

Dry Fabric

Wet Contaminants on log Ohms

1

10

100

1000

10000

100000

1000000

10000000

00000000

1E+09

1E+10

WetCememt

Flocculent CaOHSlurry

Grease Trans Oil HydraulicOil

Saline

Wet Contaminants

Dry Fabric

Practical Conclusions

• No correlation to conductivity and arc rating of contaminants.

• Wet state is often worse than dry state but only ignitable contaminants are worse than sweat/water.

• Most dry soils and many wet ones seem to be good for protection from arc flash.

• A small amount of hydrocarbons is unlikely to be life threatening.

• Proper cleaning should be regular but not need not be excessive.

Documents

Electrical - intelliquestmedia.com · – 1910.137 & 1926.97 for Electrical Protective Equipment Electrical OSHA 29 CFR 1910.269 Workplace Safety • Electric Power Generation,