In Part I of this No~Shock~Zone Stage series you learned what voltage is and a bit on how it’s measured. In this article we’ll cover how to use a basic digital voltmeter to measure any power outlet or extension cord for proper voltage. The reason this procedure is so important is that sometimes venues do crazy things with power outlets.
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If you’ve been reading along this far in the series you already know about voltage (electrical pressure) and amperage (current flow). You also know how to measure voltage using a DMM (Digital Multi Meter) and how to size extension cords for sufficient amperage (current) capacity. But in the end it all comes down to wattage.
We’ve all heard about how hooking up an RV on too long or too skinny of an extension cord can force its appliances to run on 100 volts instead of the regular 120 volts, thereby burning out the motors or other components. But before we get into the reality of what happens to gear running on 100 volts rather then a full 120 volts, let’s figure out why this voltage drop thing happens in the first place.
For those of you unfamiliar with extension cord and wire specifications, the lower the number of the gauge, the thicker the wire and the more current that can flow through it without overheating. For example, a 14-gauge extension cord might be rated for only 15 amperes of current flow, while a 10-gauge extension cord could be rated for 30 amperes of current, depending on total length of the cable and type of insulation.
An RV Hot-Skin condition occurs when the frame and body of the vehicle is no longer at the same voltage potential as the earth around it. This is usually due to an improper power plug connection at a campsite or garage AC outlet. So what follows are two ways to determine if the skin of your RV has been electrified. The first method uses a voltmeter for testing, while the second method uses a non-contact AC tester like electricians use to check for live outlets.
Most musicians really don’t want to learn about electrical engineering, or even how basic electricity works. Everyone, however, should learn how to test for and avoid electric shocks on stage. With that in mind, there are some novel ways to think about and teach basic electricity to the musician and technician.
Today’s RVs have much greater power requirements than those of even 10 years ago. You’ve got lots of appliances, so that single 20-amp outlet can’t provide enough current. This is when you need to step up to 30- or even 50-amp outlets at the campsite. Let’s see how they’re wired.
We’re running a survey on ProSoundWeb to find out just how many musicians have been shocked by a guitar or mic. Please help us find out how big a problem this is by responding to this 10-second survey.
Remember when you were a child and first started to help with baking there were all sorts of measuring devices and abbreviations to take into consideration? There was a Tablespoon (Tbsp), teaspoon (tsp), Ounce (oz.), with 8 oz. in a cup, and so on. And you better not get your tsp and Tbsp mixed up or bad things would happen to your cake. The same types of rules apply when you’re measuring any electrical values. You just need to know how to use a few electrical measuring tools and then you’re ready to test your RV power.
While RV’s as wired from the factory are inherently safe, they can become silent-but-deadly killers if plugged into an improperly wired extension cord or campsite outlet. This is because RV’s are basically a big cage of metal insulated from the ground by rubber tires. It’s up to you, the RVer, to make sure the frame and body of your RV is never electrified due to poor maintenance, bad connections, or reversed polarity in a power plug. This so called Hot-Skin problem is what causes a tingle when you touch the doorknob or metal steps of your RV while standing on the ground.