Zone concept advances. (classification of hazardous locations) Under the present NEC rules, hazardous (classified) locations are divided into divisions depending on how frequent the hazardous atmosphere or dusts are expected to be present. If the hazardo
Jul 1, 1995,
Design and engineering news and analysis in the electric construction and maintenance industry...
When service protection can be higher than ampacity
Jul 1, 1995, Stallcup, James G.
Protecting service-entrance conductors when there are motors and other loads.The basic requirement in Sec. 230-90(a) is that the fuse size or circuit...
Horsepower designations on appliances.
Jul 1, 1995, Hartwell, Frederic P.
Improperly substantiated horsepower designations on pool motors and other appliances may resize many circuit elements without increasing safety.We received...
Protecting life safety circuits in high rise buildings.
Jul 1, 1995, Staszewski, Zygmunt
Fire damage to emergency circuits in high rise buildings must be prevented. When combined with smoke and heat spread, such damage may result in far greater...
Protecting high-efficiency motor circuits.
Jun 1, 1995, Hartwell, Frederic P.
Some types of overcurrent protective devices may not prove suitable for all high-efficiency motor applications.We received a series of questions related...
How to perform short-circuit calculations.
Jun 1, 1995, Mercede, Frank J.
Performing short-circuit calculations requires an understanding of various system components and their interaction.It's very important to understand the...
Using demand data to analyze load additions.
May 1, 1995, Stallcup, James G.
Can a new commercial or industrial load be added to existing service equipment without performing an extensive standard calculation?For many years designers...
Think like a GFCI
May 1, 1995, Wells, Jack
With ever increasing locations that need GFCI protection, knowing how to select, install, and test these devices is crucial.Today's ground fault circuit...
Receptacle configurations on highly loaded circuits.
Apr 1, 1995, Hartwell, Frederic P.
There are circumstances when a plug and receptacle configuration can be used above the normal limit of 80% of their rating.We received some manufacturer's...
Adding central A C to an existing dwelling service.
Mar 1, 1995, Stallcup, James G.
Can a central air-conditioner be added to existing service conductors without upgrading the elements of the service equipment?Designers and installers...
Determining submersible pump cable sizes.
Mar 1, 1995, Duhan, Jeff
How are voltage drop calculations used in sizing submersible pump power cables?What happens when the power source for a submersible pump is not located...
Is unobstructed workspace required at all times?
Mar 1, 1995, Hartwell, Frederic P.
Although switchgear must be readily accessible and meet minimum working clearances, the entire workspace need not be readily accessible.The drawing shows...
Tying new MV feeders into an existing system.
Mar 1, 1995, Canham, James; Zec, Joseph; Pullizzi, Jack E.; Ciasulli, Mario
Power feeders for a new cooling tower require special design and installation considerations to be compatible with the existing power distribution system.Tying...
Effectively applying premium efficiency motors.
Mar 1, 1995, Cowern, Edward H.
Major guidelines will help you understand, evaluate, select, apply, and properly load premium efficiency motors.Modern premium efficiency (PE) motors...
What to know about protective relays.
Feb 1, 1995,
The successful operation of an MV distribution system depends on the proper selection and setting of switchgear relays.Protective relays are arguably...
