Class 1 division 2

hhsting

Senior Member
I have flammable storage cabinets eight of them which contain class 1 liquids. The electrical engineer has defined the area as Class 1 Division 2 per NEC 2014 Section 500.5.

However he is providing 1/0 AWG conductor attached to all cabinets which go to ground bar in room which then connects to building steel. The plans then show that in the hazardous boundary areas all wiring is non hazardous due to this grounding to building steel.

I cannot find this in NEC 2014.
Questions:

1. Is their anywhere in NEC 2014 which shows that the ground wire to flammable storage then to building steel is acceptable and would then de classify area to non hazardous?

2. Why would then engineer provide this grounding to building steel any thoughts or opinion anyone seen this?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
The bonding is probably to reduce the chances of static electricity creating a spark. It would not seem like it would change the area classification any. It only reduces the chance of a spark being generated by static electricity, not by any ingress of flammable gases into the conduit and eventually someplace where the electrical system might create a spark. A class I, division 2 area is defined as follows.

(2) Class I, Division 2. A Class I, Division 2 location is a location:
(1) In which volatile flammable gases, flammable liquid–
produced vapors, or combustible liquid–produced vapors
are handled, processed, or used, but in which the liquids,
vapors, or gases will normally be confined within closed
containers or closed systems from which they can escape
only in case of accidental rupture or breakdown of such
containers or systems or in case of abnormal operation of
equipment, or
(2) In which ignitible concentrations of flammable gases,
flammable liquid–produced vapors, or combustible
liquid–produced vapors are normally prevented by positive
mechanical ventilation and which might become
hazardous through failure or abnormal operation of the
ventilating equipment, or
(3) That is adjacent to a Class I, Division 1 location, and to
which ignitible concentrations of flammable gases, flammable
liquid–produced vapors, or combustible liquid–
produced vapors above their flash points might occasionally
be communicated unless such communication is
prevented by adequate positive-pressure ventilation from
a source of clean air and effective safeguards against
ventilation failure are provided.
The bonding wire would not change any of these three conditions that would make it a C1D2 area.

However, it is true that outside of the C1D2 area, no special wiring method provisions would be required. But I am not sure what you mean by "boundary".
 

hhsting

Senior Member
The bonding is probably to reduce the chances of static electricity creating a spark. It would not seem like it would change the area classification any. It only reduces the chance of a spark being generated by static electricity, not by any ingress of flammable gases into the conduit and eventually someplace where the electrical system might create a spark. A class I, division 2 area is defined as follows.



The bonding wire would not change any of these three conditions that would make it a C1D2 area.

However, it is true that outside of the C1D2 area, no special wiring method provisions would be required. But I am not sure what you mean by "boundary".
Boundary as in 5 feet from cabinets, 10 feet from cabinet, 30 feet from cabinet it’s still class 1 div 2 and the extent of class 1 div 2 area exists
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Boundary as in 5 feet from cabinets, 10 feet from cabinet, 30 feet from cabinet it’s still class 1 div 2 and the extent of class 1 div 2 area exists
I am not sure what you are trying to say. There is no NEC provision that requires the C1D2 area to extend 30 feet from a storage cabinet that I am aware of.

You might want to take a look at the second sentence of informational note #2 in 500.5 (B)(2), and subsequently another standard that it references.
 

hhsting

Senior Member
I am not sure what you are trying to say. There is no NEC provision that requires the C1D2 area to extend 30 feet from a storage cabinet that I am aware of.

You might want to take a look at the second sentence of informational note #2 in 500.5 (B)(2), and subsequently another standard that it references.
I am not saying 30 feet is the boundary. Plans don’t say the boundary only points to cabinets show class1 div 2 area.

Can class 1 div 2 extend outside flammable storage cabinet?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I am not saying 30 feet is the boundary. Plans don’t say the boundary only points to cabinets show class1 div 2 area.

Can class 1 div 2 extend outside flammable storage cabinet?
Did you read the second sentence of informational note #2 in 500.5 (B)(2)?

The note would appear to suggest that even inside the cabinet might not necessarily be a classified area and points to a standard that might be of more help.

Are you saying the note on the plans says only the area inside the cabinet is C1D2? if so, it would seem not to matter all that much since it is unlikely that there is any electrical wiring inside the cabinet.
 

hhsting

Senior Member
Did you read the second sentence of informational note #2 in 500.5 (B)(2)?

The note would appear to suggest that even inside the cabinet might not necessarily be a classified area and points to a standard that might be of more help.

Are you saying the note on the plans says only the area inside the cabinet is C1D2? if so, it would seem not to matter all that much since it is unlikely that there is any electrical wiring inside the cabinet.
That note says Div 1 I have Div 2?


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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
That note says Div 1 I have Div 2?


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I don't see where it says any division at all. just classified or not.
Informational Note No. 2: Piping without valves, checks, meters,
and similar devices would not ordinarily introduce a hazardous
condition even though used for flammable liquids or gases.
Depending on factors such as the quantity and size of the
containers and ventilation, locations used for the storage of
flammable liquids or liquefied or compressed gases in sealed
containers may be considered either hazardous (classified) or
unclassified locations.
See NFPA 30-2015, Flammable and Combustible
Liquids Code, and NFPA 58-2014, Liquefied Petroleum Gas Code.
 

tom baker

First Chief Moderator
Staff member
1/0 cable is for static grounding, as pointed out and is it in the scope of the NEC? This is one of the few haz locations questions I have seen that that the 500.5 classification done
 
Last edited:

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
500.4 (B)
Informational Note No. 3: For further information on protection
against static electricity
and lightning hazards in hazardous
(classified) locations, see NFPA 77-2014, Recommended Practice on
Static Electricity; NFPA 780-2014, Standard for the Installation of
Lightning Protection Systems; and API RP 2003-2008, Protection
Against Ignitions Arising Out of Static Lightning and Stray Currents.
 
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