Commercial Loads — Part 1
Jan 1, 2010, By Mike Holt, NEC Consultant
The electrical load requirements for commercial installations result in a great deal of diversity in usage....
Multifamily Dwelling Unit Service and Feeder Calculations
Dec 1, 2009, By Mike Holt, NEC Consultant
How to calculate the service for a single-family or a multifamily dwelling...
Dwelling Unit Calculations
Nov 1, 2009, By Mike Holt, NEC Consultant
Apply demand factors for correct load calculations...
Health Care Facilities
Oct 1, 2009, By Mike Holt, NEC Consultant
Article 517 provides the requirements for those parts of health care facilities involving examination and treatment of patients...
Surge Suppression Devices
Sep 9, 2009, By Mike Holt, NEC Consultant
Avoid transient voltage problems by understanding how to correctly apply Art. 285 of the National Electrical Code (NEC)...
Air-Conditioning and Refrigeration Equipment
Sep 1, 2009, By Mike Holt, NEC Consultant
Article 430, the largest Article in the NEC, is commonly understood to be the “motor” Article...
Pools and Spas — Part 3 of 3
Jun 1, 2009, By Mike Holt, NEC Consultant
How to meet Art. 680 requirements for wiring fountains, pools, and spas per the National Electrical Code (NEC)...
Pools and Spas — Part 2 of 3
May 1, 2009, By Mike Holt, NEC Consultant
How to meet Art. 680 requirements for wiring pools and spas per the National Electrical Code (NEC)...
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...
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....
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...
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....
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....
Article 450: Transformers and Transformer Vaults
May 1, 2008, By Mike Holt, NEC Consultant
The operation of any facility depends on power distribution, which, in turn, depends on transformers. Safe and reliable operation of transformers is crucial...
Article 424: Fixed Electric Space Heating
Apr 1, 2008, By Mike Holt, NEC Consultant
Considering the fact that it has nine parts, at first glance, Art. 424 might seem like overkill for a device as simple as a heater. Walk into any hardware...
Grounding and Bonding of Separately Derived Systems
Mar 1, 2008, Mike Holt, NEC Consultant
Separately derived systems (SDSs) include most transformers as well as any generator or UPS supplying a transfer switch that opens the neutral conductor....
Transformer Secondary Conductors
Feb 1, 2008, By Mike Holt, NEC Consultant
Similar to feeder taps, covered in the last issue, transformer secondary conductors can be every bit as confusing. Let's take a closer look at 240.21(C)...
Feeder Taps
Jan 1, 2008, By Mike Holt, NEC Consultant
Sometimes, it makes sense to tap into a feeder conductor to power another conductor. From Art. 100, we know that a feeder conductor runs between service...
Article 240: Overcurrent Protection
Oct 1, 2007, By Mike Holt, NEC Consultant
Article 240 provides the requirements for selecting and installing overcurrent protection devices (OCPDs). Depending on your application, other Articles...
Article 230: Services Part 2
Sep 1, 2007, By Mike Holt, NEC Consultant
Part 1 of this two-part series, which ran in last month's August issue, explored how to ensure your service entrance equipment meets Code. Starting with...
Article 230: Services Part 1
Aug 1, 2007, By Mike Holt, NEC Consultant
Article 230, which consists of seven parts, provides the installation requirements for service conductors and equipment. Parts II, III, and IV address...
