Stumped by the Code
Apr 1, 2009, By Mike Holt, NEC Consultant
Q. We have a 400A, 3-phase feeder that we want to wire with two parallel sets of 3/0 AWG conductors in the same raceway. Is this acceptable?...
Pools and Spas — Part 1 of 3
Apr 1, 2009, By Mike Holt, NEC Consultant
If Art. 680 of the National Electrical Code (NEC) has one overriding concern, it's to keep people and water separated from electricity. Article 680 applies to pools, spas, hot tubs, fountains, and similar bodies of water....
Electrical Services — Part 2
Mar 1, 2009, By Mike Holt, NEC Consultant
Looking at Fig. 230.1 in the NEC, we can see that the second and third major areas of Art. 230 provide requirements for service entrance conductors (Part...
680.26 Equipotential Bonding for Swimming Pools, Spas and Hot Tubs
Feb 19, 2009, By Mike Holt
Electrical Services — Part 1
Feb 1, 2009, By Mike Holt, NEC Consultant
If you look at Fig. 230.1 in the NEC, you'll see that Art. 230 divides neatly into three general of coverage. The first includes general requirements,...
How Much Working Space Is Enough?
Jan 1, 2009, By Mike Holt, NEC Consultant
In order to create safe working conditions, OSHA and the NEC [110.26] provide working space requirements that vary according to the hazards involved with...
Box Fill Calculations
Nov 1, 2008, By Mike Holt, NEC Consultant
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....
Illustrated Catastrophes
Nov 1, 2008, By Joe Tedesco, NEC Columnist
As usual, never consider the following commentary associated with these photos as a formal interpretation of the National Electrical Code (NEC)....
Sizing Junction Boxes
Oct 1, 2008, By Mike Holt, NEC Consultant
The sizing requirements for pull boxes, junction boxes, handhole enclosures, and conduit bodies exist to prevent conductor insulation damage. Those requirements...
Illustrated Catastrophes
Oct 1, 2008, By Joe Tedesco, NEC Columnist
As usual, never consider the following commentary associated with these photos as a formal interpretation of the National Electrical Code (NEC). Without...
What's Wrong Here?
Oct 1, 2008, By Joe Tedesco, NEC Columnist
How well do you know the Code? Think you can spot violations the original installer either ignored or couldn't identify? Here's your chance to moonlight...
Stumped by the Code?
Oct 1, 2008, By Mike Holt, NEC Consultant
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?...
Motor Calculations
Sep 1, 2008, By Mike Holt, NEC Consultant
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....
Illustrated Catastrophes
Sep 1, 2008, By Joe Tedesco, NEC Columnist
As usual, never consider the following commentary associated with these photos as a formal interpretation of the National Electrical Code (NEC)....
Fill 'Er Up
Aug 14, 2008, By Mike Holt, NEC Consultant
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....
Conductor Size Matters
Aug 1, 2008, By Mike Holt, NEC Consultant
The NEC provides minimum size requirements for conductors to prevent overheating and fire....
Illustrated Catastrophes
Aug 1, 2008, By Joe Tedesco, NEC Columnist
Alan Christofk, a superintendent with Gephart Electrical Construction in Stillwater, Minn., found this unique installation at a gas station...
Article 600: Electric Signs and Outline Lighting
Jun 1, 2008, By Mike Holt, NEC Consultant
Every commercial occupancy needs a form of identification, the standard method of which is typically the electric sign. This is one reason why you'll be working with Art. 600 if you do much commercial or industrial work....
Cathodic Protection Systems and the NEC
Jun 1, 2008, By Whitt L. Trimble and Eddie Guidry, Fluor Enterprises, Inc.
During the 2005 National Electrical Code (NEC) review cycle, a relatively simple revision was made that created a significant change on the cathodic protection (CP) systems of petroleum and chemical facilities (plants)....
