EC&M's CodeWatch - September 23, 2004 Issue

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The designations "National Electrical Code" and "NEC" refer to the National Electrical Code®, which is a registered trademark of the National Fire Protection Association.

Nightmare Installations
Retire and Rewire
When a colleague of mine recently decided to retire I offered to rewire his cabin, which had originally been wired in the early '60s when county/city inspections were nonexistent. To my surprise, we found the following problems: No individual circuit breaker or fuse had been installed for individual branch-circuit overcurrent protection; all branch-circuit conductors were terminated on the main disconnect load side lugs (total 10), so regardless of the size of the individual conductor, they were all protected by 100A main fuses; and there was no junction box for the splice point. All the splices were made by removing insulation from the conductors and wrapping them with insulation tape. Despite all that, the system had worked fine for the previous 40 years without a fire. After completely revamping the system, I told my friend he could sleep with confidence.
Jesse Sandhu
Sacramento, Calif.

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Too Hot in the Hot Tub
One night after a rain storm, I stepped into the spa in my newly built screened enclosure and felt a tingle. Given my electrical background, I should have cut and run then. Instead I thought I must have been imagining things and stepped back in, only to feel the tingle again. So I got my voltmeter and measured between the nearest ground (a poorly grounded piece of EMT) and the wet concrete around the spa and got 90V. It's a wonder I wasn't electrocuted. I then had my wife turn the outside flood lights on and off. When they were off, there was no voltage. When they were on, I measured 90V. It turns out that the people who installed the screened enclosure had nicked a run of romex that fed the flood lights. The whole frame was energized.
Henry Morgan
Ocoee, Fla.

Send your 200-word story to us and it may appear in a future issue of CodeWatch. Authors of stories chosen for publication will receive $25.

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Applications Corner
Code Calculations
By Mike Holt
According to the U.S. Census Bureau, there are more than 3,500 recreational and vacation camps in the United States. That's a lot of supply facility sites for recreational vehicles. Although the work may not be performed on a regular basis, do you know the rules for sizing services for these facilities? If not, read on and then test your skills by tackling our sample question.

Recreational vehicle parks are calculated according to the demand factor of Table 551.73. The total calculated load is based on:
• 2,400VA for each 20A supply facilities site
• 3,600VA for each 20A and 30A supply facilities site
• 9,600VA for each 50A, 120/240V supply facilities site

Ready for a quiz? A recreational vehicle park has 42 sites: three are rated 50A, 240/120V; 30 are rated 30/20A; and nine are rated 20A. What's the minimum feeder demand load for these sites?

158kVA
101kVA
139kVA
65kVA

Visit EC&M's Web site for the answer.

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Code Challenge

What's Wrong Here?
By Joe Tedesco
How does this installation violate NEC requirements?

Hint: Store merchants use these receptacles to light up trees along the sidewalk.

Code Q&A
By Mike Holt
Q. I don't see where 300.4 limits the number of NM cables through a given opening in wood or metal framing members. I don't want to turn the framing members into Swiss cheese and reduce their structural integrity by boring a hole for every NM cable. So how many NM cables can I install in each bored hole?
See the answer.

Code Quiz
By Steven Owen
Imagine a metal junction box that is 32 inches x 32 inches x 6 inches with two 4-inch EMT raceways connected directly across from one another on opposite walls. Each 4-inch raceway contains three 250 kcmil conductors. An additional 2-inch EMT raceway, which contains three 4/0 AWG XHHW conductors, is connected to the back wall of the junction box directly opposite the removable cover, and another 2-inch EMT raceway has been connected to the bottom of the enclosure for a tap to a piece of industrial equipment. The 4/0 AWG conductors, which pass through the junction box, are installed in the 2-inch raceways. What's the minimum dimension required between either of the 4-inch raceways (installed in a horizontal position) and the 2-inch raceway connected to the bottom of the enclosure (installed in a vertical position)? Note: No conductors are installed between either of the 4-inch raceways or either of the 2-inch raceways.

32 inches

24 inches

4 inches

No requirement for this installation

Visit EC&M's Web site for the answer and explanation.

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Faces of the Code
Tony Sardina
Member, Code-Making Panel 17
Tony Sardina became a principal on CMP-20 midway through the 2002 Code cycle -- he moved to CMP-17 in 2003 when the panels were rearranged -- but his relationship with the Code extends back to before he even began working in the electrical industry. Like his high school classmates, he carried math and history books in his backpack, but he had one more that most of them didn't: the NEC. At age 16 he took a construction class that included a unit on electrical wiring and regular open-book tests on the Code. "At first, it was a little hard to understand," he says. "But once you got into it and started reading a little bit, it made a lot of sense how those requirements had to be applied."

That early understanding came in handy 23 years ago when he took a job with HVAC manufacturer Carrier, where he worked for several years as a service engineer, doing everything from helping customers work through installation issues to conducting load testing on electric heaters. "I kind of hit all aspects of the business," he says.

He further rounded out his knowledge of the Code several years ago when he left Carrier for a brief period and took a job installing room air conditioners and transport refrigeration systems on truck trailers. The field experience gave him a different perspective on the Code, something that he put to use when he began serving on the Code-making panels. "A lot of times [while working on the Code] I've come across a safety concern that I experienced in the past, so I've tried to help write the requirement to prevent problems in the future," he says. "That experience helped me develop a clearer understanding of how the Code should be written so the layperson can really understand it. You don't want it to be like opening up a Greek dictionary."

After returning to Carrier, he became a customer service manager, fielding questions from both end-users and internal engineers. The change in responsibilities means he's not as close to the design and engineering side as he used to be, but he's not ready to give up his position on the panel for at least another cycle. "I may no longer be an engineer, but I want to stay affiliated with the Code because I like it," he says.

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Speak Out
First Contact
Tony Sardina had the unique opportunity to learn about the Code long before he made the decision to enter the electrical field. Did you have experience with the NEC prior to taking your first job in the industry? Visit www.ecmweb.com to tell us.

Regardless of whether serving on multiple standards-making bodies actually makes it difficult to make useful contributions to each committee, the majority of CodeWatch readers (56%) thought it was a bad idea. If you serve on multiple standards-making bodies, we want to hear about it. E-mail us at mhalverson@primediabusiness.com

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The National Electrical Code Internet Connection, the No. 1 rated Code Web site in the world, offers the following FREE products:
Books, Code Quiz, DVDs, Graphics for PowerPoint, Newsletter, Online Training, Posters, Simulated Exams, Software, Video clips, and Videos
Visit www.NECcode.com and stay current with important industry issues.

Shows and Events
EC&M Code Seminars
Procrastinators rejoice. Because some of you may have received EC&M's previous e-mail registration deadline alert later than expected, we're extending the registration deadline to Sept. 24 for the Atlanta, Philadelphia, Chicago, and Orlando Code Change Conferences. That's tomorrow! Download the registration form, fill it out and fax it to (203) 929-5351. Moderated by Mike Holt and Fred Hartwell (Boston conference only), the two-day conferences will offer a comprehensive look at the 2005 Code. All attendees will receive a copy of the 2005 NEC and EC&M's 2005 Code Change Book, written by Mike Holt.

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