Code Q&A
Q. What is the maximum height that a safety switch can be installed?
Box Fill Calculations
Box fill isn't just the number of wires in the box — it's the total volume of the conductors, devices, and fittings in a box.
Code Q&A
Q. How do you size the ground wire when running conductors in parallel?
Code Q&A
Q. Our utility requires a nonfused disconnect upstream of the meter and service disconnect for certain services. Is this legal?
Sizing Junction Boxes
The sizing requirements for pull boxes, junction boxes, handhole enclosures, and conduit bodies exist to prevent conductor insulation damage. Those requirements
Code Quandaries
Q. I have a 1,200A, 480V panel that has a working space of 3½ feet. The engineer says 7 feet is required. Is he correct?
Code Q&A
Q. We have motors that are interlocked, preventing them from being on at the same time. Do we still have to add them up for service and feeder calculations?
Code Q&A
Q. Is a disconnect required to be within sight of electric space-heating equipment if the unit has a factory-installed circuit breaker?
Motor Calculations
To prevent a motor from burning up, you must provide a means of protecting it from overcurrent (overload, short circuit, or ground fault). If you can remember not to confuse motor protection with circuit protection, you’ll eliminate a major point of confusion in motor calculations.
Code Q&A
Q. What is the smallest size wire you can use for a lighting fixture whip?
Stumped by the Code?
Q. Am I required to secure Type MC cable that is located under a raised floor of an information technology equipment room?
Fill Er Up
Raceways must be large enough to hold conductors without overheating and avoid insulation damage during conductor pulls. Therefore, we must determine the maximum number and size of conductors to put in a given raceway. That limit is what we mean by raceway fill.
Code Q&A
Q. What is the maximum number of bathroom receptacles that can be placed on the 20A, 120V bathroom receptacle circuit in a single-family dwelling?
Conductor Size Matters
The NEC provides minimum size requirements for conductors to prevent overheating and fire.
