The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Practical Electricity And House Wiring
On the other hand most cities, states and other municipalities cooperate with these two organizations so that their recommendations generally speaking become law in the locality in question. The operation is as outlined in the following paragraphs:
"Listed by Underwriters."-—The Underwriters' Laboratories is as the name implies chiefly a laboratory. Manufacturers before placing an item on sale submit samples to the Laboratories, who make elaborate and complete tests. If the item then meets all requirements, it is listed in the Underwriters official "List of Inspected Electrical Appliances" and henceforth is known as "Listed by Underwriters Laboratories"—most people say "Approved by Underwriters." It remains on this list only so long as the manufacturer maintains the quality found in his original sample. The manufacturer must mark each and every piece he produces so that it can always be identified.
Re-Examination Listing.—Items so listed, with most subsequent tests made in the Laboratories, fall into what is known as "Re-examination Listing." Examples are sockets, outlet boxes, receptacles and appliances such as toasters.
Label Listing.—Other items are more frequently tested, and often the Laboratories' representatives make such tests regularly in the various factories. Such merchandise is individually labelled thus falling into the "Label Listing" classification. The label may be an actual label, or the information may be molded into or stamped on the merchandise itself. Tests for this type of listing are usually more severe and more frequently repeated than for Re-examination service.
As an example, every foot of rubber-covered wire after manufacture is put up into reels all in one length, then submerged in water. The two ends are of course brought up above the water. After 12 hours, 1500 volts of electricity, 7 times greater than the voltage that it will probably ever meet in use, is applied for one minute and any reel that breaks down is definitely rejected. This is one of several tests. If that reel meets all other required tests successfully, it is dried, cleaned, put up into standard coils and only then is the Underwriters label applied to the coil.
Other types of wire must meet other equally severe tests depending on the purpose for which they are intended, and receive one label for every factory coil. On the other hand, weatherproof wire, which as explained in another chapter is not so likely to cause trouble under any circumstances, receives no labels but falls under the "Re-examination Listing" classification. At the other extreme we have flexible lamp cords such as found on floor lamps, appliances, etc. Because the ultimate customer who buys it is seldom versed in electrical matters, and since he buys usually only a few feet, it is most important that labels be generously used. Consequently we find that labels are applied every five feet —a "bracelet" of metal and paper. When this label is seen on a cord it is "Listed Cord."
