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#103256 - 06/14/02 02:03 PM Classify this Location
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA


This is a waste water treatment facility.

501.11 Flexible Cords, Class I, Divisions 1 and 2.

A flexible cord shall be permitted for connection between portable lighting equipment or other portable utilization equipment and the fixed portion of their supply circuit.

Flexible cord shall also be permitted for that portion of the circuit where the fixed wiring methods of 501.4(A) cannot provide the necessary degree of movement for fixed and mobile electrical utilization equipment, in an industrial establishment where conditions of maintenance and engineering supervision ensure that only qualified persons install and service the installation, and the flexible cord is protected by location or by a suitable guard from damage. The length of the flexible cord shall be continuous.

Where flexible cords are used, the cords shall be as follows:

(1) Of a type listed for extra-hard usage
(2) Contain, in addition to the conductors of the circuit, a grounding conductor complying with 400.23

(3) Connected to terminals or to supply conductors in an approved manner

(4) Supported by clamps or by other suitable means in such a manner that there is no tension on the terminal connections

(5) Provided with suitable seals where the flexible cord enters boxes, fittings, or enclosures of the explosionproof type

Exception: As provided in 501.3(B)(6) and 501.4(B).

Electric submersible pumps with means for removal without entering the wet-pit shall be considered portable utilization equipment.

The extension of the flexible cord within a suitable raceway between the wet-pit and the power source shall be permitted.

FPN:See 501.13 for flexible cords exposed to liquids having a deleterious effect on the conductor insulation.
_________________________
Joe Tedesco, NEC Consultant

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2014 / 2011 NEC & Related Books and Study Guides
#103257 - 06/15/02 03:09 AM Re: Classify this Location
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Joe,
Are you sure that this cord is not part of a float assembly? It looks like the old floats we used to connect for control, and that would be part of a UL listed assembly for the area anyway.

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#103258 - 06/15/02 07:23 AM Re: Classify this Location
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA


George: If this is what is below the top level of the wastewater, I believe the references shown above stands as the required rule. I have asked someone from the site to respond to the questions asked here on the BB.
_________________________
Joe Tedesco, NEC Consultant

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#103259 - 06/15/02 08:21 AM Re: Classify this Location
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
Joe,
Who said that that part of the waste treatment process is a classified area? Not all areas of the process have the potential to create the methane gas that requires an area classification. This appears to be at the sludge end, which in treatment plants that I have worked one was not a classified area.
Don
_________________________
Don(resqcapt19)

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#103260 - 06/15/02 08:28 AM Re: Classify this Location
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
I agree with Don that this looks like the sludge end (I'm an expert, we WON'T go into why) but the fan you're showing looks like it's from the aeration basin. Our fans (much bigger than that one though) came UL from the manufacturer with rubber cord already on them.

It really doesn't look like that fan would even turn in that..........material.

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#103261 - 06/15/02 09:03 AM Re: Classify this Location
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
NFPA 820
Standard for Fire Protection in Wastewater Treatment and Collection Facilities
1999 Edition

Chapter 1 Introduction
1-1 Scope.
1-1.1 General.
1-1.1.1*
This standard provides minimum requirements for protection against fire and explosion hazards in wastewater treatment plants and associated collection systems, including the hazard classification of specific areas and processes.
1-1.1.2
This standard shall apply to the following:
(1) Collection sewers
(2) Trunk sewers
(3) Intercepting sewers
(4) Combined sewers
(5) Storm sewers
(6) Pumping stations
(7) Wastewater treatment plants
(8) Sludge-handling facilities
(9) Chemical-handling facilities
(10) Treatment facilities
(11) Ancillary structures (see definition in Section 1-5)
1-1.1.3
This standard shall not apply to the following:
(1) Collection, treatment, or disposal of industrial wastes or manufactured by-products that are treated on-site and not discharged to a publicly or privately operated municipal facility
(2) On-site treatment systems (see definition in Section 1-5)
(3) Pressure sewer systems (see definition of Sewer, Pressure in Section 1-5)
(4) Building drain systems and appurtenances (see definition in Section 1-5)
(5) Industrial sewer systems and appurtenances (see definition of Sewer, Industrial in Section 1-5)
(6) Personnel safety from toxic and hazardous materials or products of combustion
(7) Separate nonprocess-related structures (see definition in Section 1-5)
1-1.2 Alternative Methods.
Nothing in this standard shall prevent or discourage the use of alternative methods, materials, practices, or devices, provided technical data are submitted to the authority having jurisdiction to demonstrate that the alternative method, material, practice, or device is equivalent to or superior to the requirements of this standard.
1-1.3 Fire Risk Evaluation.
A fire risk evaluation shall be initiated early in the facility design or alteration to integrate the fire prevention and fire protection requirements described in this document.


NFPA 820 - Chapter 4 Solids Treatment Processes

4-1* General.

This chapter provides minimum criteria for protection against fire and explosion hazards associated with solids treatment processes. This chapter shall not apply to the treatment of solids from industrial waste treatment processes. Tables 4-2(a) and 4-2(b) summarize the various components associated with solids treatment processes.

4-2* Design and Construction.

The design and construction of solids treatment processes shall conform to Tables 4-2(a) and 4-2(b).

Table 4-2(a) Solids Treatment Processes



A
B
C
D
E
F
G



Location and Function
Fire and Explosion Hazard
Ventilation
Extent of Classified Area
NEC-Area Electrical Classification (All Class I, Group D)
Material of Construction for Buildings or Structures
Fire Protection Measures

1

COARSE AND FINE SCREENINGS- HANDLING BUILDINGS Storage, conveying, or dewatering of screenings (no exposed flow of wastewater through building or area)
NA
NR
NA
Unclassified
NC, LC, or LFS
H, FE, and FAS

2

GRIT-HANDLING BUILDING Storage, conveying, and dewatering of heavy small screenings and grit (no exposed flow of wastewater through building or area)
NA
NR
NA
Unclassified
NC, LC, or LFS
H, FE, and FAS

3
a
SCUM-HANDLING BUILDING OR AREA Holding, dewatering, or storage
Possible grease or flammable liquids carryover
A
Enclosed space
Division 2
NC, LC, or LFS
H, FE, and CGD if enclosed

b
B

Unclassified


c
Not enclosed, open to atmosphere
NA


4
a
SCUM PITS
Buildup of vapors from flammable or combustible liquids
A
Enclosed —entire space
Division 1
NC
H, FE, and CGD if enclosed

b
B

Division 2
NC, LC, or LFS


c
Not enclosed, open to atmosphere
Within a 10-ft (3-m) envelope around equipment and open channel1


5
a
SCUM-PUMPING AREAS Pumping of scum, wet side ofpumping station
Carryover of floating flammable liquids
A
Enclosed —entire space
Division 1
NC
H, FE, and CGD if enclosed

b
B

Division 2
NC, LC, or LFS


c
Not enclosed, open to atmosphere
Within a 10-ft (3-m) envelope around equipment and open channel1


6
a
SCUM-PUMPING AREAS Pumping of scum, dry side of pumping station
Not significant
D
Enclosed space
Division 2
NC, LC, or LFS
FE

b
C

Unclassified


c
Not enclosed, open to atmosphere
NA


7

SCUM INCINERATORS2 Elimination of scum through burning
Firebox explosion from possible carryover of flammable scum
NR
Incinerator area if separated from scum storage
Unclassified
NC, LC, or LFS
FSS (if indoors), H, and FE

8
a
SLUDGE THICKENER (CLARIFIER) Sludge concentration and removal, gravity, or dissolved air flotation
Possible generation of methane from sludge; carryover of floating flammable liquids
A
Enclosed —entire space
Division 1
NC


b
B
Division 2
NC, LC, or LFS
H, FE, and CGD if enclosed


c
Not enclosed, open to atmosphere
Envelope 18 in. (0.46 m) above water surface and 10 ft (3 m) horizontally from wetted walls1


9
a
SLUDGE PUMPING STATION DRY WELLS Dry side of a sludge pumping station
Buildup of methane gas or flammable vapors
D
Entire dry well when physically separated from a wet well or separate structures
Division 2
NC, LC, or LFS
H and FE

b
C
Entire dry well when physically separated from a wet well or separate structures
Unclassified


10
a
SLUDGE STORAGE WET WELLS, PITS, AND HOLDING TANKS Retaining of sludge
Possible genera-tion of methane gas in explosive concentrations; carryover of floating flammable liquids
A
Enclosed —entire space
Division 1
NC
CGD, H, and FE if tank enclosed in structure

b
B
Division 2
NC, LC, or LFS


c
Not enclosed, open to atmosphere
Envelope 18 in. (0.46 m) above water surface and 10 ft (3 m) horizontally from wetted walls1
NR


11
a
SLUDGE-BLENDING TANKS AND HOLDING WELLS Retaining of sludge with some agitation
Possible genera-tion of methane gas in explosive concentrations; carryover of floating flammable liquids
A
Enclosed —entire space
Division 1
NC
H, FE, and CGD if tank enclosed in structure

b
B
Division 2
NC, LC, or LFS


c
Not enclosed, open to atmosphere
Envelope 18 in. (0.46 m) above water surface and 10 ft (3 m) horizontally from wetted walls1
NR


12

DEWATERING BUILDINGS CON-TAINING CENTRI-FUGES, GRAVITY BELT THICKENERS, BELT AND VACUUM FILTERS, AND FILTER PRESSES Removal of water from sludge and the conveyance of sludge or sludge cake
NA
NR
NA
Unclassified
NC, LC, or LFS
FE, FDS, and FAS

13

INCINERATORS2 AND INCINERATOR BUILDINGS Conveying and burning of sludge cake
Firebox explosion
NR
NA
Unclassified
NC, LC, or LFS
FSS (if indoors), H, and FE

14

HEAT TREATMENT UNITS, LOW- OR HIGH-PRESSURE OXIDATION UNITS Closed oxidation of sludge
None, other than in high-pressure systems
NR
NA
Unclassified
NC, LC, or LFS
H and FE

15
a
ANAEROBIC DIGESTERS, BOTH FIXED ROOF AND FLOATING COVER Generation of sludge gas from digesting sludge
Leakage of gas from cover, piping, emergency relief valves, and appurtenances
Not enclosed, open to atmosphere
Tank interior; areas above and around digester cover; envelope 10 ft (3 m) above the highest point of cover, when cover is at its maximum elevation, and 5 ft (1.5 m) from any wall
Division 1
NC
H and FE

b
Envelope 15 ft (4.6 m) above Division 1 area over cover and 5 ft (1.5 m) beyond Division 1 area around tank walls
Division 2


c
A
For digester tanks enclosed in a building: tank interior; entire area inside building
Division 1
NC
CGD if enclosed


d
B
For digester tanks enclosed in a building: tank interior; areas above and around digester cover; envelope 10 ft (3 m) above highest point of cover, when cover is at its maximum elevation, and 5 ft (1.5 m) from any wall of digester tank
Division 1
NC
CGD if enclosed


e
Remaining space in enclosed area
Division 2
NC, LC, or LFS


16
a
ANAEROBIC DIGESTER CONTROL BUILDING Storage, handling, or burning of sludge gas
Leaking and ignition of sludge gas
A
Entire building
Division 1
NC
CGD, H, and FE

b
B
Enclosed areas that contain gas-handling equipment
Division 2
NC, LC, or LFS


c
C
Physically separated from gas-handling equipment
Unclassified


17
a
DIGESTER GAS-PROCESSING ROOMS Gas compression, handling, and processing
Sludge gas ignition
A
Entire room
Division 1
NC
CGD, H, and FE

b
B
Division 2
NC, LC, or LFS


c
B
Within 5 ft (1.5 m) of equipment
Division 1
NC, LC, or LFS


18

ANAEROBIC DIGESTER GAS STORAGE Storage of sludge gas
Gas storage piping and handling
NNV
Within a 10-ft (3-m) envelope of tanks, valves, and appurtenances
Division 1
NC, LC, or LFS
H, FE, and CGD

19

CHLORINE OXIDATION UNITS Chlorine reaction with sludge
Chlorine is a very strong oxidizing agent
NR
NA
Unclassified
NR (These unit processes use corrosive chemicals that require the use of specific materials of construction. Special consideration shall be given to such materials of construction.)
H and FE

20
a
UNDERGROUND (PIPING) TUNNELS CONTAINING NATURAL GAS PIPING OR SLUDGE GAS PIPING Transmission of gas, sludge, water, air, and steam via piping; also might contain power cable and conduit
Ignition of natural gas or sludge gases
D
Within 10 ft (3 m) of valves and appurtenances
Division 1



b
D
Entire tunnel
Division 2
NC, LC, or LFS
CGD, FDS, and FE


c
C
Areas within 10 ft (3 m) of valves, meters, gas check valves, condensate traps, and other piping appurtenances
Division 2


d
C
Areas beyond 10 ft (3 m)
Unclassified


21

UNDERGROUND (PIPING) TUNNELS NOT CONTAINING NATURAL GAS PIPING OR SLUDGE GAS PIPING Transmission of sludge, water, air, and steam piping; also might contain power cable and conduit
NA
NR
NA
Unclassified
NC, LC, or LFS
FDS and FE

22
a
COMPOSTING PILES Aerobic sludge reduction
Liberation of ammonia and toxic gas (com-posting materials can self-ignite)
D
Enclosed area
Division 2
NC, LC, or LFS
H and FDS

b
C
Unclassified


23
a
IN-VESSEL COMPOSTING Aerobic sludge reduction
Liberation of ammonia and toxic gas (composting materials can self-ignite)
As required by process
If enclosed, interior of reactor vessel plus a 10-ft (3-m) envelope around reactor vessel
Division 2
NC
H and FDS

b
Areas beyond 10 ft (3 m)
Unclassified


24
a
ODOR-CONTROL SYSTEM AREAS Areas physically separated from processes that house systems handling flammable gases
Leakage and ignition of flammable gases
D
Entire area if enclosed
Division 2
NC, LC, or LFS
CGD, FDS, and FE

b
C
Areas within 3 ft (1.5 m) of leakage sources such as fans, dampers, flexible connections, flanges, pressurized unwelded ductwork, and odor-control vessels
Division 2


c
Areas beyond 3 ft (1.5 m)
Unclassified


25

PUMPING OF DRAINAGE FROM DIGESTED SLUDGE-DEWATERING PROCESSES Pumping of centrate, filtrate, leachate, drying beds, and so forth
NA
NR
NA
Unclassified
NC, LC, or LFS
H



Note: The NR designation in column C indicates that no ventilation requirements are established for the space and, therefore, Table 7-3.1 also has no requirements.
1The area beyond the envelope is unclassified.
2See NFPA 54, National Fuel Gas Code; NFPA 82, Standard on Incinerators and Waste and Linen Handling Systems and Equipment; NFPA 8501, Standard for Single Burner Boiler Operation; and NFPA 8502, Standard for the Prevention of Furnace Explosions/Implosions in Multiple Burner Boilers.
A — No ventilation or ventilated at less than 12 air changes per hour
B — Continuously ventilated at 12 air changes per hour or in accordance with Chapter 7
C — Continuously ventilated at 6 air changes per hour or in accordance with Chapter 7
CGD — Combustible gas detection system
D — No ventilation or ventilated at less than 6 air changes per hour
FAS — Fire alarm system
FDS — Fire detection system
FE — Portable fire extinguisher
FSS — Fire suppression system (e.g., automatic sprinkler, water spray, foam, gaseous, or dry chemical)
H — Hydrant protection in accordance with 5-2.4
LC — Limited-combustible material
LFS — Low flame spread material
NA — Not applicable
NC — Noncombustible material
NEC — In accordance with NFPA 70, National Electrical Code
NR — No requirement




Table 4-2(b) Solids Treatment Processes — Sludge Drying



A
B
C
D
E
F
G



Location and Function
Fire and Explosion Hazard
Ventilation
Extent of Classified Area
NEC-Area Electrical Classification (All Class II, Group G)
Material of Construction for Buildings or Structures
Fire Protection Measures

1

SLUDGE- DRYING PROCESSES1
Potential for ignition of dust
NR
Entire room2
Division 13
NC (Construction in accordance with NFPA 68 and NFPA 69)
H, FAS, and FSS (See NFPA 61 and NFPA 69.)

Note: The NR designation in column C indicates that no ventilation requirements are established for the space and,therefore, Table 7-3.1 also has no requirements.

1 See NFPA 54, National Fuel Gas Code; NFPA 82, Standard on Incinerators and Waste and Linen Handling Systems and Equipment; NFPA 8501, Standard for Single Burner Boiler Operation; and NFPA 8502, Standard for the Prevention of Furnace Explosions/Implosions in Multiple Burner Boilers.

2 The area beyond the envelope is unclassified.

3 If acceptable to the authority having jurisdiction, it shall be permitted to be determined in accordance with classifications in NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

FAS — Fire alarm system

FSS — Fire suppression system (e.g., automatic sprinkler, water spray, foam, gaseous, or dry chemical)

H — Hydrant protection in accordance with 5-2.4

NEC — In accordance with NFPA 70, National Electrical Code

NC — Noncombustible material

NR — No requirement

I could not reproduce the tables, it appears that you may both be incorrect when it comes to the classification of an area like this one.

[This message has been edited by Joe Tedesco (edited 06-15-2002).]
_________________________
Joe Tedesco, NEC Consultant

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