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NEC questions 015

By Mike Holt, based on the 2002 NEC, 1 the 2

Q1. Go the NEC forced lighting fixtures in a factory to have a cover to protect versus breaking bulbs?

A1. No, the NEC walk not call for lamp security for this application. However, lamps used for basic illumination of momentary installations must be defended from accidental call or wrong by a an ideal fixture or lampholder v a guard <527.4(F)>.

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Q2. Go the NEC state the number of NM cables allowed under a single staple?

A2. No. NM cable should be secured and also supported in accordance v 334.30 which claims that nonmetallic-sheathed cable need to be secured by staples, cable ties, straps, hangers, or comparable fittings designed and installed so as no to damage the cable. However, this ar does not specify the maximum number of cables allowed under a solitary staple.

As always, the installation need to be authorized by the authority having jurisdiction <90.4>, so basically it"s up to the inspector.

Q3. I heard that the Code just permits one tools grounding (bonding) conductor to end on a grounding block screw terminal. Is this true?

A3: No, the variety of equipment ground connection (bonding) conductors permitted to end on a grounding terminal is limited in accordance with the devices manufacturers accuse <110.3(B)> post on the label located inside the panelboard. But generally, two and sometimes three equipment grounding (bonding) conductors can be terminated to a solitary terminal. However be careful, just one base (neutral) conductor is permitted on a solitary terminal <408.21>.

Q4. A drinking water fractional is proposed to be set up within a 1 ft of a transformer. Is there a Code rule that governs the essential clearance between the drink fountain and the transformer? A4. Yes, 110.26 requires sufficient step-back working space from energized parts, measured from the enclosure front, not be much less than the distances had in Table 110.26(A)(1). Suspect this is a 480 come 208V transformer, the minimum step-back working space according to this table is 3½ ft. However the water fountain/cool can be located right beside the transformer sides as lengthy as the transformer ventilating openings are not clogged <450.9>.

Q5. Is GFCI protection forced for a 15 or 20A, 125V receptacle the is provided to supply power for a water cooler (water fountain)? A5. No. Q6. What is the maximum variety of circuit breakers allowed to be installed in a panel?

A6. The maximum number of circuit breakers permitted in a panelboard is limited by the indict posted inside the panelboard <110.3(B)>. However, the NEC states that not much more than 42 overcurrent gadgets can be installed in any one cabinet <408.15>.

Q7. As soon as does the NEC call for a key breaker in a load center?

A7. Each lighting and appliance branch-circuit panelboard need to be defended on the supply next <408.16(A)>. The overcurrent protection deserve to be located within the panelboard, or the panelboard"s feeder overcurrent protection maker could be provided if that is rating does no exceed the ampere rating that the panelboard <408.16(A) Ex.1>. Q8. Is there a password limitation as to the total ampere rating of all circuit breakers in a panel? Example: could the total ampere rating of all circuit breakers in a 100A dashboard exceed 100A?

A8. This is not a password issue. The amount of the ampere rating of the circuit breakers in a panelboard is irrelevant. As a issue of fact, the is very common because that the complete ampere rating of the branch breakers in a panelboard to much exceed the rating that the panelboard.

Q9. Once is an insulating bushing forced on raceway fittings?

A9. Conductors 4 AWG and larger that get in an enclosure have to be safeguarded from abrasion during and after environment by a fitting that offers a smooth, rounded insulating surface, such together an insulating bushing <400.4(F)>.

Rigid nonmetallic conduit male-adapter discontinuation fittings room sometimes thought about to provide the compelled smooth rounded insulating surface. Yet check v the authority having actually jurisdiction.

One critical thing, insulating bushings aren"t required where a raceway terminates in a threaded raceway entrance that offers a smooth, rounded, or flared surface for the conductors. An example would it is in a meter hub installation or a Meyer"s hub-type installation <400.4(F) Ex.>.

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Q10. Is over there anything in the NEC that states that a receptacle mounted in a ceiling need to be that the twist-lock type?

A10. No.

2002 NEC exercise Questions book — 2002
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