E2 Plan Review and Inspections 5

Question 1

A commercial plan shows a panelboard installed in a bathroom of an office building. What does the NEC say about this installation?

Accepted Answer

NEC 240.24(E) prohibits overcurrent devices (including panelboards) in bathrooms of any occupancy

Answer

Panelboards may be installed in bathrooms if they are in GFCI-protected locations

Answer

NEC 408.37 prohibits overcurrent devices in bathrooms of dwelling units but not commercial bathrooms; verify local amendment

Answer

Commercial bathrooms are exempt from all NEC panelboard location restrictions

Question 2

During a plan review, the electrical drawings show conductors with 75°C termination ratings on equipment with 60°C terminal ratings. What is the correct action?

Accepted Answer

Require the conductors to be sized using the 60°C column of NEC Table 310.16 to match the terminal rating per NEC 110.14(C)

Answer

Accept the plans since higher-rated conductors always exceed minimum requirements

Answer

Allow the installation if the conductors are in conduit with adequate fill

Answer

Accept the plans if the overcurrent device is rated for 75°C conductors

Question 3

An inspector is reviewing plans for a commercial building addition. The plans show a new feeder tapped from an existing panelboard busbar using a tap conductor that is smaller than the feeder conductors. Under what conditions does the NEC permit this tap?

Accepted Answer

The tap is permitted if it follows NEC 240.21 tap rules, such as the 10-foot or 25-foot tap rule with appropriate termination at a protected panel

Answer

Taps from panelboard busbars are never permitted; only lugs may be used

Answer

Tap conductors are permitted at any size as long as they are in conduit

Answer

The tap is only permitted if the existing panel is rated for 200A or more

Question 4

A final inspection of a commercial building reveals that some circuit breakers in the main distribution panel are double-tapped (two conductors under one breaker lug). What is the inspector's required action?

Accepted Answer

Require correction unless the breaker is listed and labeled for two conductors per NEC 408.41

Answer

Allow double-tapping if both conductors are the same gauge

Answer

Permit double-tapping only on breakers rated 20A or less

Answer

Accept the installation if the panel has a main breaker protecting all circuits

Question 5

During a commercial building inspection, an inspector checks a transformer room and finds that the primary overcurrent device is rated at 300% of the transformer's primary full-load current. The transformer is 45 kVA, 480-208Y/120V. Is this compliant with the NEC?

Accepted Answer

Yes, NEC 450.3(B) permits primary overcurrent protection up to 300% for certain transformer sizes

Answer

No, NEC 450.3(B) limits primary overcurrent protection for transformers over 9 kVA to 125% of primary full-load current

Answer

Yes, any overcurrent device rating is acceptable if the transformer has thermal protection

Answer

No, primary overcurrent protection must always match the transformer's primary full-load current exactly

Question 6

An inspector reviewing commercial as-built drawings after final inspection notices that conduit fill was not verified on a 3-inch rigid conduit containing twelve 4/0 AWG THWN conductors. How should the inspector verify compliance?

Accepted Answer

Count the conductors and confirm with Annex C of the NEC that the fill does not exceed 40% for more than 2 conductors

Answer

Measure the conduit internal diameter and accept the installation if at least 1 inch of space remains

Answer

As-built drawings are informational only and conduit fill does not need to be verified after installation

Answer

Verify compliance only if the circuit has tripped due to overheating

Question 7

A plan review for a commercial building shows that the emergency egress lighting is powered from the normal lighting panelboard with no separate emergency source. Which NEC article directly governs this requirement?

Accepted Answer

NEC Article 700, which requires emergency systems to have an independent power source capable of operating in the event of normal power failure

Answer

NEC Article 210, which governs branch circuit requirements for lighting

Answer

NEC Article 410, which covers luminaire installation requirements

Answer

NEC Article 230, which governs service entrance conductors