Code Quandaries

Jan 1, 2001 12:00 PM, By Mike Holt

At EC&M, we know NEC issues are very important to our readers. That’s why we’ve dedicated a monthly department to answering your latest Code questions and concerns. When you find yourself stumped by the Code, just e-mail your question to mike@mikeholt.com for future consideration in our Code Quandaries column.

Q1. We recently moved a large circuit breaker to make room for some heavy industrial equipment. Now, the load conductors will not reach the bottom of the circuit breakers. Instead of running new wire, the customer wants us to back-feed the circuit breaker—they want us to make the line conductors terminate to the bottom of the breaker and the load conductors terminate to the top of the breaker. The manufacturer of the heavy industrial equipment insists we can connect the line or load to either end of the circuit breaker. However, many of the electrical people at our facility believe the NEC requires the supply to terminate to the top terminals and the load to terminate to the bottom terminals. I haven’t been able to find this regulation in the NEC. Help!

Q2. I have a question regarding the proper connection to a circuit breaker, and I can’t find anyone who can steer me in the right direction. I understand it is common practice to connect the line side to the top of the breaker and the load side to the bottom of the breaker. However, if you have an underground service entering a CT cabinet where the main breaker is directly above, why must you still wire the line side to the top of the breaker? In this situation, it’s obvious where the line side originates. Doesn’t the breaker function the same way whether you feed it from the top or the bottom? Does the NEC cover this?

A. Yes. Sec. 110-3(b) states that “listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.” According to Underwriters Laboratories Inc.’s “General Information Directory,” you must wire breakers marked “Line and Load” so the supply (line) terminates to the “Line” terminal and the feed (load) terminates to the “Load” terminal. You can wire circuit breakers with no “Line and Load” markings in either direction (see Fig. 1).

Q. I installed a panel on the wall of a bathroom in a commercial building where the distance from the front of the panel to the toilet is 5 ft. Is it legal to install a panel in a commercial bathroom?

A. Yes. Sec. 240-24(e) only prohibits overcurrent devices in bathrooms* of dwelling units and guest rooms of hotels and motels. Since this is not a residential bathroom, the NEC permits installation of the panel in the bathroom. But be careful: Sec. 230-70 prohibits the installation of the service disconnecting equipment in any bathroom.
*A bathroom is an area including a basin with one or more of the following: a toilet, tub, or shower (Art. 100 definition).

Q. If you secure a wraparound-style fluorescent fixture to a T-bar ceiling, can you run a cord out of the top of the fixture to a receptacle located in the ceiling area, provided that the ceiling space is not used as a plenum area and is located in an office?

A. Maybe. Sec. 410-14(a) permits you to connect electric-discharge lighting fixtures supported independently of the outlet box to the branch circuit by flexible cord if:
* The fixture requires adjusting or aiming [Sec. 410-31(a)]. (Not in this case.)
* The fixture is directly below the outlet box, the flexible cord is visible for its entire length outside the fixture, and the cord is not subject to strain or physical damage [Sec. 410-41(c)].

Q. My local inspector believes that the bending radius on 500kcmil conductors entering the back of a 6-in.-deep enclosure was violated. The inspector passed the installation but said he would not the next time. Can you use a 6-in.-deep enclosure, such as a panel cabinet, for 500kcmil conductors entering the back of an enclosure?

A. Yes. Conductors shall not be deflected (bent) within a cabinet or cutout box unless sufficient width (in this case depth) is provided, in accordance with Table 373-6(a). This table requires a minimum of 6 in. of width (depth) in the cabinet so you can properly deflect (bend) 500kcmil conductors.

Q. Is it legal to run Uf feeder cable in the same ditch with water pipe?

A. Yes. No NEC rule requires that underground raceways or cables be separated from other piping systems, but underground conductors for satellite dishes and antennas [Sec. 810-18(a)], direct-buried coaxial cable [Sec. 820-11(b)], and network-powered broadband communications cables must be at least 12 in. from conductors of light or power circuits.