Licensed Electrical Contractor FREE Licensed Electrical Contractor Special Occupancies and Equipment Questions and Answers 3

Question 1

Per NEC Article 680, what is the minimum burial depth for a direct-buried cable supplying a pool pump motor when not under a building or concrete?

Accepted Answer

18 inches

Answer

NEC 680.10 and Table 300.5 require a minimum cover of 18 inches for direct-buried UF cable supplying pool equipment when not under a building or concrete.

Question 2

In a Class II, Division 1 hazardous location containing combustible dust, which of the following enclosure types is required for electrical equipment?

Accepted Answer

Dust-ignitionproof enclosure

Answer

NEC Article 502 requires dust-ignitionproof enclosures in Class II, Division 1 locations to prevent ignition of combustible dust accumulations.

Question 3

What is the required working space depth in front of electrical equipment rated 277 volts to ground with exposed live parts on one side and grounded parts on the other per NEC Table 110.26(A)(1)?

Accepted Answer

3.5 feet

Answer

Per NEC Table 110.26(A)(1), Condition 2 at 151-600 volts requires a minimum working space depth of 3.5 feet.

Question 4

Per NEC Article 511, above what height in a commercial repair garage are Class I, Division 2 requirements no longer applicable?

Accepted Answer

18 inches above floor

Answer

NEC 511.3(A) classifies the area up to 18 inches above the floor as Class I, Division 2 in commercial garages where lighter-than-air gases are not present.

Question 5

What bonding requirement does NEC Article 680 impose on metal parts of a pool structure, including reinforcing steel?

Accepted Answer

All metal parts must be bonded together with a minimum 8 AWG copper conductor

Answer

NEC 680.26 requires equipotential bonding of all metal parts associated with the pool structure using a minimum 8 AWG solid copper conductor.

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Licensed Electrical Contractor FREE Licensed Electrical Contractor Special Occupancies and Equipment Questions and Answers 3