Basics of US Hazardous Locations Requirements a condensed version
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Seminar Modules
• Organization of Participant Manual
• Module 1: History of Hazardous Locations
• Module 2: Overview of Area Classifications
• Module 3: Class I Division and Zone Comparison
• Module 4: Overview of Protection Techniques
• Module 5: Class I, Division 1 Construction/Performance
Requirements
• Module 6: Class I, Division 2 Construction/Performance
Requirements
• Module 7: Class I, Zone 0 and 1 Construction/Performance
Requirements
• Module 8: Class I, Zone 2 Construction/Performance Requirements
• Module 9: Class II & III, Construction/Performance Requirements
• Module 10: Installation
• Module 11: European Compliance Overview/International Markets
Slide 2

Module 1 Objectives
• Discuss the history behind hazardous locations
• Explain the relationship between the history and the development of
Article 500 through 506 in the National Electric Code
Slide 3
Module 1 Objectives
• Discuss the history behind hazardous locations
• Explain the relationship between the history and the development of
Article 500 through 506 in the National Electric Code
Slide 4

1920 - National Electric Code (NEC) Timeline
• “Equipments in Extra Hazardous
Locations”
• Addressed rooms in which highly flammable gases, liquids, mixtures or other substances were used
•
At this time, UL had been certifying equipment for use in such areas for about 6 years
Slide 5
1960’s – National Electric Code (NEC) Timeline
• UL develops Westerberg Explosion Test Vessel (WETV)
• WETV is able to determine two quantities for any gas or vapor
• flame transmission properties by measuring the Maximum
Experimental Safe Gap (MESG)
• explosion pressure
•
WETV data enables classification of gases and vapors into defined groups by comparing the MESG and explosion pressure to those of materials already defining the group.
Slide 6

1969 – National Electric Code (NEC) Timeline
• UL publishes Bulletin of Research no. 58 which summarizes a UL investigation of fifteen flammable gases or vapors based on WETV data.
• Added to NEC in 1971
Slide 8
1996 – National Electric Code (NEC) Timeline
• NEC introduces International Zone Classification system in new Article 505
• covers Class I only
• includes 3 gas groups, IIA, IIB, & IIC
• includes 3 Zones- 0, 1, & 2
• UL begins certifying equipment for use in such areas
Slide 9

• National Electrical Code (NFPA 70)
• Articles 500 through 506
•
Canadian Electrical Code (C22.1)
• Section 18
• IEC/EN 60079-series
• Special Applications
• Mine Safety and Health Administration (MSHA)
- Regulates mining locations
- Certifies equipment
- Governed by Federal Mine Safety and Health Act
• United States Coast Guard (USCG)
- Regulates off-shore locations
- Governed by USCG Regulations, 46CFR Parts 110-113 inclusive (based on NEC )
Slide 10
• Authority Having Jurisdiction (AHJ)
• Determines acceptability of equipment
• Thousands nationwide
• International Association of Electrical Inspectors (IAEI)
• Fire marshals
• Other local authorities
• U.S. Certification Marks still basis for acceptance
(NRTL)
Slide 11

Listed
Western Electric Motors, Inc.
Cat. No. MNO
Listed
D3J8
Electric Motor for Hazardous Locations
Class I, Division 1, Group D
230 V, 60 Hz
3 phase
54 A
20 HP
1760 rpm
Insulation class B

This label indicates
Listing
From NEC:
Slide 12
Area Classifications
• Class I
• Flammable, gases, vapors or liquids
• Class II
• Combustible dusts
• Class III
• Ignitible fibers and flyings
Slide 13

Class I Division/Zone Area Classification
Comparison
Division 1: Where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or some of the time under normal operating conditions
Division 2: Where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions
Zone 0: Where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or for long periods of time under normal operating conditions
Zone 1: Where ignitable concentrations of flammable gases, vapors or liquids can exist some of the time under normal operating conditions
Zone 2: Where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions
Slide 14
Class I Division/Zone, Gas Group Comparison
Division 1 and 2
A (acetylene)
B (hydrogen)
C (ethylene)
D (propane)
Zone 0, 1 and 2
IIC (acetylene & hydrogen)
IIB (ethylene)
IIA (propane)
Slide 15

Class I Division/Zone Temperature Class
Comparison
Division 1 and 2
T1 (<450º C)
T2 (<300º C)
T2A,B,C,D
(<280º C, <260º C, <230º C, <215º C)
T3 (<200º C)
T3A,B,C,
(<180º C, <165º C, <160º C)
T4 (<135º C)
T4A (<120º C)
T5 (<100º C)
T6 (<85º C)
Zone 0, 1 and 2
T1 (<450º C)
T2 (<300º C)
T3 (<200º C)
T4 (<135º C)
T5 (<100º C)
T6 (<85º C)
T5 and T6 are optional for marking
Slide 16
Listing Mark
 This panel is safe in a
Division 1 area.
 Inside the panel are IS barriers, which provide power to an intrinsically safe device.
Slide 18

Classification Mark
ABC Enclosures, Inc.
Cat. No. XCX
As to explosion and fire hazard only
3IJ2
Enclosure for Use in Hazardous Locations
Class I, Group C and D
WARNING - To prevent ignition of hazardous atmospheres, all conduit runs must have a sealing fitting connected within 18 in . of the enclosure.
CAUTION - To prevent ignition of hazardous atmospheres, disconnect from the supply circuit before opening enclosure. Keep tightly closed when circuits are alive .
• Example: Explosionproof
Enclosures
• For this product, only the enclosure has been tested
• (electrical components have not been evaluated)
Slide 19
Recognized Component Mark
• This mark is for incomplete products
• The UL Report will include Conditions of Acceptability that must be checked during evaluation of the final Listed assembly
Slide 20

Comparison of Product Markings
0539 II 2 G
Class I, Div. 1,
Group C,D
Class I, Zone 1
AEx d IIB T5 or
Class I, Zone 1
AEx d IIB T5 Gb
Class I, Div. 1,
Group C,D
Ex d IIB T5 or
EEx d IIB T5
Ex d IIB T5 or
Ex d IIB T5 Gb or
Ex db IIB T5
<Certificate No.>
Ex d IIB T5 or
Ex d IIB T5 Gb or
Ex db IIB T5
<Certificate No.>
Slide 21
Ordinary Location Requirements
• For all equipment:
• Risk of Fire
• Risk of Electric Shock
• Special Applications:
• Environmental Ratings
• Marine Ratings
• Signaling/Fire Alarm
Slide 22

• withstanding an explosion of a specified gas or vapor within the enclosure,
• preventing the ignition of a specified gas or vapor surrounding the enclosure, and
• operating at an external temperature that will not ignite a specified gas or vapor surrounding the enclosure
Slide 23
Enclosure with enlarged gap, ready for an explosion test
1
2
3
Slide 24

Each frame = 1/2000 seconds
4
5
6
Slide 25
• Group C (IIB)
• Enclosure Volume 2000 cm³ (122 in³)
Explosionproof
Div 1 = zone 0 &1
19.1 mm (3/4 in)
Flameproof
Zone 1
12.5 mm Width
(min.)
Clearance
(max.)
0.05 mm (0.002 in) 0.2 mm
Slide 26

Explosionproof enclosure
Explosionproof enclosure
Slide 27
Slide 28

Explosionproof Pushbutton Switch
Cylindrical Joint --->
Flat Joint--->
Threaded Conduit Entries
<---Threaded Joint
Slide 29
Control Drawing
Hazardous (Classified)
Location
Unclassified (Non hazardous)
Location
18.8.8
Red
Black
I.S.
Transmitter
_
+
Dual Channel
Barrier
+24 V
Control
Equipment
SIGNAL
Equipment
Vmax (or Ui)
Imax (or Ii)
Ci + Ccable
Li + Lcable
Pmax
>
>
<
<
>
Barrier
Voc (or Uo)
Isc (or Io)
Ca (or Co)
La (or Lo)
Po

Sugar Refinery
After an Explosion
Slide 31
Slide 32

• The suitability of these paths to prevent entrance is determined by the following requirements:
• Joint widths and clearances
• Shaft lengths and clearances
• Thread engagement
• Gasketing
• Dust Penetration testing
Slide 33
Dust Testing
• Nozzles are directed where the dust is most likely to enter the enclosure. Goes on for 30 h, during that time the device is powered on and off for 6 heating and cooling cycles. The heating/cooling cycle creates a partial vacuum that will possibly draw the dust into the enclosure .
Slide 34

• Nozzles directed where dust most likely will enter into the motor.
• After test, the motor is opened and must not have any dust inside.
Slide 35
Articles 500 – 506 of the NEC
• Article 500 - General
• Article 501 - Class I, Division Locations
• Article 502 - Class II Locations
• Article 503 - Class III Locations
• Article 504 - Intrinsically Safe Systems
• Article 505 - Class I, Zone Locations
• Article 506 - Zone 20, 21 and 22 Locations
Slide 36

Specific Occupancies
• Covered in Articles 510 through 517
• Include such occupancies as:
• Commercial Garages (Art. 511)
• Aircraft Hangars (Art. 513)
• Motor Fuel Dispensing (Art. 514)
• Bulk Storage Plants (Art. 515)
• Spraying, Dipping, and Coating Applications (Art. 516)
• Health Care Facilities (Art. 517)
• Special requirements for equipment
• Wiring methods
• Sealing and drainage
• Flexible cords
• Grounding
Slide 37
Slide 38

Section 501.10(A) Wiring Methods, Division 1
• Threaded rigid metal conduit
• Threaded steel intermediate conduit
• Mineral Insulated (MI) cable
• Rigid non-metallic conduit
• encased in 2 in. of concrete, and
• buried under 2 ft. of earth
• Metal Clad (MC-HL) cable
• Listed for Division 1
• gas/vaportight continuous corrugated metallic sheath
• overall polymeric jacket
• separate grounding conductors
Slide 39
Section 501.10(A) Wiring Methods, Division 1
Cont’d
• Instrumentation Tray Cable (ITC-HL)
• Listed for Division 1
• gas/vaportight continuous corrugated metallic sheath
• overall polymeric jacket
• Flexible connections
• only permitted when necessary
• listed flexible fittings
• Intrinsically Safe Wiring – See Article 504
Slide 40

Flexible Connection
Slide 41
MI Cable (Mineral Insulated)
<---- MI Cable
Slide 42

MC-HL Cable Fitting
Slide 43
Section 501.10(B) Wiring Methods, Division 2
• Threaded rigid metal conduit
• Threaded steel intermediate conduit
• Enclosed gasketed busways
• PLTC cable
• ITC cable
• MI cable
• MC cable
•
•
•
•
ts
Slide 44

Conduit Seal
Factory Sealed Enclosure
Slide 45
Slide 46

• Seals shall be integral with enclosure or a separate sealing fitting must be provided
• Compound
• resistant to surrounding atmosphere
• melting point of 93º C or greater
• thickness equal to or greater than trade size of conduit but no less than 5/8 inches = 16 mm.
• No splices or taps allowed
• Conductor fill 25% maximum unless approved for greater
Slide 47
Section 501.140 Flexible Cord Cont’d
• Cord must be continuous
• Extra hard usage
• Grounding conductor
• Supported to avoid stress at terminal connections
• Sealed at entry to explosionproof enclosures
Slide 48

• Article 250 provisions apply
• Section 250.100 requires bonding in hazardous locations regardless of voltage
• Locknut bushing and double locknut contacts not acceptable for bonding
Slide 49
• Section 504.10(A)-control drawing
• Section 504.20-wiring methods
• any for unclassified areas permitted
• Section 504.30-separation of conductors
• Section 504.50-grounding
• Section 504.70-sealing
Slide 50

• Open wiring- 50 mm (2 inches)
• In raceways-not permitted unless:
- 50 mm (2 in.) separation and secured or partition provided between
- where all conductors of intrinsically safe or nonintrinsically safe are in grounded metal sheathed or metal clad cables where sheathing or cladding is capable of carrying fault current to ground
• Within enclosures - 50 mm (2 in.)
Slide 51
* Thank You For Attending!
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Slide 53