Letters: Reader Feedback
Power for security In the article “Quality Power for Security Systems” (Pure Power, Fall 2007, p. 17) the author gives “underground local metal structures (gas piping, for example)” as one of the legal ways of connecting a grounding system to the earth. The author refers to the National Electrical Code for the listing.
Power for security
In the article “Quality Power for Security Systems” (Pure Power, Fall 2007, p. 17) the author gives “underground local metal structures (gas piping, for example)” as one of the legal ways of connecting a grounding system to the earth. The author refers to the National Electrical Code for the listing. But according to NEC Article 250-52(a), “a metal underground gas piping shall not be used as a grounding electrode.” Can the author expand on this?
Igor A. Altshuler Engineer Baltimore via the internet
Indeed, you are most correct. The statement should have read “Other local metal underground piping (except gas lines).” Likewise, tanks that have been used to store explosive or hazardous contents should not be used as supplemental grounding electrodes. An acceptable example would be an abandoned underground metallic water storage tank that has been filled with moist sand.
Jay Adams Applications Engineer Transtector Systems Shayden, Idaho
The story “The climate has changed for energy efficiency” ( www.csemag.com , 10/22/07) said that “the energy used by commercial and industrial buildings in the United States is responsible for 45% of the nation's greenhouse gas emissions.” This is encouraging for the potential to make a big dent in those emissions. Although most domestic and non-domestic buildings are very wasteful of energy, in many ways that waste is easier to tackle in non-domestic buildings: First, the energy bill is usually much higher in non-domestic buildings, so there are greater financial rewards to be achieved by investing time into improving energy efficiency. There's a big economy-of-scale effect in the savings that can be achieved by investing time into energy management.
Second, the larger the building, the greater the chance that it already has interval metering equipment and access to interval energy data from that equipment. For buildings that don't have such equipment, the larger they are, the greater the payback from investing in such equipment. Analysis of such interval energy data for energy management purposes can easily lead to identification of huge sources of energy waste that would be very difficult to find without that data. Admittedly, these benefits will spread into the domestic sector as interval metering catches on there. Ultimately, the greatest energy saving are from motivating people to do their bit. This can be difficult in a work or home environment, but initiatives such as the Kilowatt Crackdown can make a huge difference.
Martin Bromley Energy Management Consultant via the internet