wjm@whuxk.UUCP (10/18/83)
There is a very simple way to protect yourself from power line voltage spikes. You install a transient supressor (for all you fellow EE's out there on the net it consists of some metal-oxide varistors connected between the "hot" side of the line and ground). A bonus is that it will also give your equipment some protection against lightning strikes on or near the power line, but it is NOT a substitute for proper lightning protection installed on any outdoor FM or TV antennae. There are two ways to do this: 1. If you want to protect your entire house, GE makes one that you can wire into your circuit breaker box (local codes permitting, else you'll have to get an licensed electrician to do it). You just connect the two black wires to the two "hot" wires coming into to the box on the "load" side of the main breaker SAFETY NOTE - BE SURE TO TURN OFF THE MAIN BREAKER OR MAIN SWITCH BEFORE DOING ANY WORK IN THE MAIN PANEL BOX AND KEEP YOUR FINGERS, TOOLS, ETC AWAY FROM THE HOT CONTACTS ON THE "LINE" SIDE OF THE MAIN BREAKER OR SWITCH. and the green wire to the ground connection in the box. 2. If you live in an apartment, or don't feel comfortable mucking around in the panel box (and don't feel like getting an electrician in to do it for you), Radio Shack makes a plug-in version that you can plug into any GROUNDED (3 prong) wall receptacle. You plug the transient suppressor into the receptacle and they plug your equipment into it. It works quite well - I've been using one for several years now. They're also quite reasonably priced - around $12.00 or so. Bill Mitchell Bell Laboratories Whippany, NJ (whuxk!wjm)
wjm@whuxk.UUCP (10/19/83)
One additional point about power line spike protection that rabbit!jj reminded me about (thankx). Be sure to use devices that are UL approved (or CSA approved if you are a Canadian reader of the net). Both the GE and Radio Shack devices I mentioned in my original article have UL approval (and I think CSA approval as well but check for yourself to be sure). For safety, it is essential to only use approved devices in any electrical system, and the National Electrical Code (as well as many local codes) requires that devices be listed (approved) by a recognized testing laboratory (generally this is UL) for the purpose that they will be used for. While we're on the subject, one should check new audio equipment that one is purchasing for UL, CSA, or equivalent (such as the German VDE) approval, since this tells you that the gear passed safety checks for shock and fire hazards before it left the factory and provides some protection for you and anyone else near your equipment. Also, be sure to check your equipment for leakage current after doing any repairs on it - and make sure the technician checks it for safety after it is repaired in the shop. If you don't know how to do a leakage check, DON'T fix your own stuff until you learn how - Its a very simple procedure and is outlined in many books on audio and TV repair and only requires a reasonably high impedance AC voltmeter and some small components. Bill Mitchell Bell Laboratories Whippany, NJ (whuxk!wjm)