Vintage Radio Special Pilot Issue September 1993 Electrical Safety For Restorers Those of us who cut our assign to it quietly and teeth as electronic without incident. experimenters during the Yet most of us are also heyday of the vacuum tube aware that, improperly learned how to work safely insulated and fused, the around high voltages and household power line can currents as we acquired our lash out with powerful and technical know-how. The dangerous sparks or (perhaps dangers were made known to even worse) quietly overheat us by our advisors and the wiring within our walls teachers, the more until it reaches the point of responsible hobby writers of ignition. So here are the the time, and sometimes by first and most obvious sad personal experience. precepts of a.c. line safety: Today, though, a new (1) make sure that all of the radio hobbyist is unlikely to electric wiring in your home have that background. In Don't turn this one on until you get some knobs! Any is correctly fused or breakered for its current- this day of low-voltage, low metal surface on an a.c.-dc. radio should be considered current, semiconductor carrying capacity and (2) aserious shock hazard. circuits, even people with make sure never to plug in electronics expertise may be devices with known short- unaware of the hazards lurking within a tube radio the circuit hazards (such as radios having cracked or frayed moment its plug is inserted into a wall socket. line cords). Precautions us older types take automatically, without Besides being a fire hazard, the a.c. power-line can even thinking about it, really need to be explained to the also dish out uncomfortable, and even fatal, shocks. In new collectors and restorers so that they can enjoy our order to avoid being on the receiving end of one of hobby without jeopardizing their safety. And that's just these, it's important that you know a little bit about what Ihope to accomplish here. how power is distributed to your home. The key facts The shock hazards associated with a plug-in tube to keep in mind are that (1) one of the two wires in radio come from two sources: the a.c. power line and every 115-volt electrical circuit is connected to ground the high d.c. voltages developed within the set to operate and (2) that the ground, especially when damp, is an its vacuum-tube circuitry. Let's take a look at the excellent conductor of electricity. power line first. If even slightly damp, the concrete in your basement floor is also an excellent electrical conductor of Power Line Hazards electricity. And, of course, the floor is in direct contact For most people the familiar household wall outlet with ground. So if your workshop is in the basement, inspires little awe. It's aconvenient source of power for you have aspecial hazard to consider. lamps, vacuum cleaners, tools, or whatever useful Placing a bare part of your anatomy in contact with appliances we feel like plugging in at the moment. With the floor (or with ametal chair or workbench frame that few exceptions, the power is always there when we want stands on the floor) is the same as touching it to the it, always goes where it is needed and does the work we grounded wire in awall outlet. If you now come in Basic Information for the Radio Collector and Restorer contact with something connected to the very serious safety hazard. It meant ungrounded, or "hot", side of the line--say that the set's d.c. plate-supply circuitry Vintage Radio while probing the innards of aradio, your was no longer isolated from the power body will complete the circuit across the line. In fact, one side of the line Vintage Radio will be published monthly, beginning with thc January, line and you will experience anasty shock. became the negative connection for the 1994 issue, by Marc F. Ellis, P.O. Box If the parts of your body completing the plate supply and, as such, was usually 1306, Evanston, IL 60204-1306. wired directly to the radio's metal Annual subscription rates are as circuit are a foot and a hand, the shock follows: via surface mail $20.00 (U.S.), will pass through your entire body--which chassis. $21.50 (Canada--U.S.funds); via air to As aresult, depending on which way other countries, $35.00 (U.S. Funds). can be extremely unhealthy, or worse. Editorial content copyright 1993 by the radio's line cord was inserted into Marc F. Ellis, except as otherwise the wall socket, the metal chassis was noted. Vintage Radio and Marc F. Ellis are not responsible either for the either at ground potential (no great outcome of any transaction resulting problem) or connected to the "hot" from advertising in this publication or for any consequences of the application side of the line. In the latter case, the of our editorial content. Please note unwary user who touched the chassis, that subscription and advertising rates, or any metal part associated with it, as well as magazine format, are subject to revision at any time. while also touching agrounded object or surface would definitely receive a Classified Advertising Each subscriber may place one free serious shock. Trading Post ad up to 30 words long in Back in the 1930's, when any issue. Additional words are 15 cents each. Subscriber ads may run for transformerless sets were first up to two issues without resubmitting. Outlet with ground fault interruption is introduced, consumer safety was not Please indicate whether you wish your nearly as much of asocietal concern as ad to run for one or two issues. great safety feature, installs in place of Trading Post rate for nonsubscribers is it is today. It was considered adequate 30 cents per word. Only non- standard outlet. to provide the radio with aback cover commercial buy, sell or trade ads for radio-related items are eligible for protecting the user from contact with So the morals for the restorer are these: inclusion in Trading Post. the chassis. However that cover was Commercial classified advertising will if you have a basement workshop, try to usually made of a fragile fiber appear in our Yellow Pages section. place yourself and any metal benches or Yellow Pages space is priced at the rate material, and it's the exception, rather of $25.00 per quarter (three months) for chairs on an insulating surface such as a than the rule, to find one still intact an ad of up to 30 words. Additional rubber mat or wood platform. And as a words are 90 cents each. "Business today. matter of principle, avoid poking around card" ads will be run at the 30-word Before you plug in any radio for the rate. in aplugged-in radio with your bare hand- Vintage Radio reserves the right to first time, particularly if it is a small -unless you're using an isolation make minor editorial adjustments table model, check to see if it's without advance notification and to transformer, which we'll discuss later. refuse advertising at our discretion. We equipped with apower transformer. If Another good precaution for any will reprint, without charge, any ad not, be yery careful once the plug goes containing typographic errors, but will workshop, basement or not, is to replace into the wall. There will be a strong assume no other financial responsibility the electrical outlet on the bench with one for losses due to such errors. possibility that the chassis, not to equipped with ground fault interruption. mention the control-knob shafts and Display Advertising Properly installed, such an outlet will Rates and size requirements for the chassis-mounting screws under the automatically shut off the power as soon display advertising will appear in the cabinet, arc now hot to ground with January, 1994 issue. as any current begins to flow (through the full line voltage. Actually, even your body or otherwise) between the "hot" How to Reach Us transformer sets should be treated with To order asubscription or send in an side of the line and any external ground. advertisement, write Vintage Radio, respect; their chasses can sometimes P.O. Box 1306, Evanston, IL 60204- Connect an ordinary power strip (properly become "hot" because of leaky bypass 1306. Please include full payment for equipped with a grounding plug) to this your transaction, including any fee for capacitors. extra words. Classified ads should be outlet to obtain additional protected The only way to work on an a.c.- submitted on a separate sheet from outlets. GFI outlets are available, at d.c. radio safely is to use an bolation other correspondence. We can be reasonable cost, at most hardware and reached by phone at (708) 869-5016. transformer. The primary of such a home-center stores. transformer is connected to the 115- volt a.c. line, and the secondary puts BE A CHARTER SUBSCRIBER! The AC-DC Set--A Safety Nightmare out 115 volts to the radio under test. We have great plans for Vintage Radio, And speaking of power-line hazards, the However the radio is now completely but we can't be successful without some common "a.c.-d.c." set represents one of isolated from the a.c. line, no matter regular readers. For that, we need your the worst. This type of radio is so named which way the plug is inserted into the help. So here's an inducement. If you because, in addition to operating on a.c., send in asubscription to Vintage Radio wall, because there is no direct between now and January 31, 1994 it could run on the d.c.