This report describes and characterizes with quantifiable electrical and thermal measures the extent to which loose electrical connections in residential-type branch circuits have overheated in the laboratory. With loose electrical connections, which conceivably could be inadvertantly duplicated in field installations, but with otherwise normal installation and operating conditions, visible glows have been observed under laboratory test conditions in nominal 120 volt, 15 and 20 ampere branch circuits with both copper and aluminum wire.Characteristics of the glow condition are differentiated from arching/sparking as sometimes observed in making or breaking electric circuits.Glowing electrical connections may dissipate as much as 35 watts of power with a current of 15 amps in the circuit and as much as 5 watts with a current of 0.8 amp in the circuit.Temperatures over 750°F were measured on the "break-off tab" of receptacles. Metal outlet boxes housing glowing connections in an insulated wall test set-up representative of a common type of residential construction attained temperatures in excess of 450°F. In laboratory tests under repetitive, intermittent and periodic cycles, a connection on a steel wire-binding screw of a receptacle open to the air had sustained glow conditions maintained for over 100 hours.Glowing connections will not perceptibly affect the electrical performance function of lights, appliances or other electrical loads, and will not "blow" fuses, trip circuit breakers or operate ground fault circuit interrupters.

A laboratory study of one-story and split-level experimental drainage systems where the vents in some cases were varied from one to six pipe-sizes smaller than those presently specified by codes showed satisfactory hydraulic and pneumatic performance under various loading conditions.The research was originally sponsored by the National Association of Home Builders and the National Bureau of Standards and more recently by a program of the Department of Defense through the Tri-Services Investigational Committee on Building Materials. This paper presents criteria recommended for the design and evaluation of systems using reduced-sized vents and a sizing table for one-and two-story systems. The laboratory work also contributed to the development of analytical and test procedures needed for evaluating the application of reduced-size venting to a broad range of innovative drain-waste-vent designs for buildings of any height. This work indicates that, in some circumstances, reduced-size venting might be a good alternative to other types of drainage systems for multi-story buildings which use conventional or innovative venting concepts. Because this study involved only a limited number of drainage system designs, it is recommended that ongoing field and laboratory studies be explored if code changes are contemplated to permit the use of smaller vents.

The purpose of the work presented in this paper was to make preliminary determinations under laboratory conditions of temperatures that might develop on residential electrical wiring covered by thermal insulation when carrying rated currents or currents slightly above rated values.The results show that temperatures on conductors surrounded by thermal insulation can greatly exceed the maximum service temperature for the wire insulation.Results also show that some types of insulation currently used to retrofit buildings may fill wall outlet boxes and contact the current-carrying elements and connections of duplex receptacles.This study indicates need for a concentrated study of temperatures that might develop on residential electrical wiring covered by thermal insulation.

Residential electric circuits are subjected to surge voltages resulting from load switching in buildings, and from external causes such as lightning. Laboratory test data are presented on high voltage breakdown values for armored cable (type AC cable), nonmetallic-sheathed cable (type NM), flat conductor cable, and duplex receptacles. Dielectric withstand voltage test requirements in current standards for residential wiring and wiring devices vary over a wide range. In some cases, the standard test voltage values for both wiring and wiring devices are less than surge voltages recorded on wiring in residences. Also field recorded voltage wave forms and rates of their application are different from those used in standard withstand voltage tests.

In view of the present accepted practice in this cou. try for building technology, common U.S. units of measurement have been used throughout this document. In recognition of the position of the United States as a signatory to the General Conference on Weights and Measures, which gave official status to the metric SI system of units in 1960, assistance is given to the reader interested in making use of the coherent system of SI units by giving conversion factors applicable to U.S. units used in this document.