Chapter 5 Special Occupancies

Question 1

What classified hazardous location has ignitible concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid produced vapors under normal operation; where they frequently exist above their flash point because of repair or maintenance; or exist because of breakdown or fault and electrical equipment may become a source of ignition.

Answer 1

Class 1 Division 1 Article 500.5(B)(1)

Question 2

What classified hazardous location has ignitible concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid produced vapors normally confined in containers or closed systems where a rupture or breakdown my happen; where their presence is normally prevented by mechanical ventilation.

Answer 2

Class 1 Division 2. Article 500.5(B)(2)

Question 3

What classified hazardous location has the presence of combustible dust in quantities sufficient to produce explosive or ignitible mixtures under normal operation; where mechanical failure may cause such mixtures to be produced; or where hazardous quantities of Group E combustible dusts are present.

Answer 3

Class 2 Division 1 Article 500.5(C)(1)

Question 4

What classified hazardous location has the presence of combustible dust in quantities sufficient to produce explosive or ignitible mixtures due to abnormal operation; where mechanical failure may cause such mixtures to be produced; or where hazardous quantities of Group E combustible dusts are present.

Answer 4

Class 2 Division 2 Article 500.5(C)(2)

Question 5

What classified hazardous location has the presence of easily ignitible fibers/flyings which are handled, manufactured, or used.

Answer 5

Class 3 Division 1 Article 500.5(D)(1)

Question 6

What classified hazardous location has the presence of easily ignitible fibers/flyings that are stored or handled other than in the process of manufactured.

Answer 6

Class 3 Division 2 Article 500.5(D)(2)

Question 7

Explosion proof equipment shall be permitted as a protection technique for which hazardous (classified) locations?

Answer 7

Class 1 Division 1 and 2 locations

Article 500.7(A)

Question 8

Dust ignitionproof equipment shall be permitted as a protection technique for which hazardous (classified) locations?

Answer 8

Class 2 Division 1 and 2 locations

Article 500.7(B)

Question 9

Dust tight equipment shall be permitted as a protection technique for which hazardous (classified) locations?

Answer 9

Class 2 Division 2 and class 3 Division 1 and 2 locations

Article 500.7(C)

Question 10

How many threads must be engaged on conduit and fittings entering explosion proof equipment?

Answer 10

5 threads

Article 500.8(E)(1)

Question 11

Conduit seals in Class 1 Division 1 and 2 locations, entering an explosion proof enclosure shall be installed within ____ inches of the enclosure.

Answer 11

18”

Article 501.15(A)(1)[2]

Question 12

Conduit seals in Class 1 Division 1 and 2 locations, where two or more explosion proof enclosures are connected with a single run less than 36” shall be permitted to have ____ seal installed as long as it is within ____ inches of each enclosure.

Answer 12

1 seal, 18”

Article 501.15(A)(3)

Question 13

Besides the entry of explosion proof enclosures, where else shall seals be installed in the conduit run?

Answer 13

Within 10’ of the hazardous locations boundary

Question 14

The thickness of a Class 1 Division 1 and 2 seal shall not be less than ____ inch thick.

Answer 14

5/8”

Article 501.15(C)(3)

Question 15

This is a circuit in which any spark or thermal effect is incapable of causing ignition of a mixture of flammable or combustible material in air under prescribed test conditions.

Answer 15

Intrinsically Safe Circuit

Article 504.2

Question 16

True or False

Intrinsically safe circuits are permitted to be in raceways of non-intrinsically safe circuits.

Answer 16

False

Article 504.30(A)(1)

Question 17

True or False

Intrinsically safe circuits are permitted to be in enclosures with non-intrinsically safe circuits.

Answer 17

True

Article 504.30(A)(2)

Question 18

Intrinsically safe systems shall be permanently labeled as such. When using color coding for the purpose of labeling what color shall be permitted?

Answer 18

Light Blue

Article 504.80(C)

Question 19

What article goes over the separate hazardous location classifications called zones?

Answer 19

Article 505 and 506