tic audio installation basics iii
how to install outdoor speaker power systems
testing the ac power systems for your outdoor sound system
There is good reason to test the 117 VAC that powers your sound system. You can spot problems such as polarity reversal that might cause excessive hum, or more importantly, you can determine if the electrical system is wired properly, and therefore, is safe. While it is rare, if the electrical system is wired incorrectly, it is possible to get a nasty shock simply by touching a metal cabinet of a sound system component, or even the metal case of a microphone. You can perform the tests on the electrical circuits using either an AC outlet testing plug or an ordinary volt-ohm meter. See Fig. 1
warning!
Fatal Voltage and current are present at a live outlet. Be sure to follow all safety precautions when testing the outlet. Do not touch the exposed metal of the testing leads while they are inserted in an electrical outlet.
fig. 1
using a volt-ohm meter for outdoor speaker power systems
While an outlet testing plug is very convenient, it is not necessary to determine if the electrical wiring is faulty. A Volt-Ohm meter suitable for use with 120 VAC is all you need. The tests assume a three-wire (grounded) polarized outlet, as shown in Fig. 1 If the outlet is wired correctly, the short slot on the right is the “hot” side of the line, and the longer slot on the left is the neutral side. The rounded hole beneath is earth ground.
Prior to conducting the tests, set the meter to measure VAC. If your meter is not auto-ranging, select a range higher than 120 volts.
Test 1.
Insert the test probes into the hot and neutral slots. It doesn’t matter which probe goes in which slot. You should get a reading of about 117 VAC (it may range from 111 to 123 VAC). If you don’t, the outlet may not be powered, or the test probes for the meter may not be making contact inside the outlet.
warning!
If the meter reads 220 VAC when conducting Test 1, it could indicate that the neutral wire is “lifted”, and the outlet is receiving both sides of the incoming 220 volts from the circuit breaker panel. This must be corrected immediately, as a serious hazard and risk to health exists.
Test 2.
Insert the test probes into the hot and ground slots. You should get a reading of approx. 117 VAC.
Test 3.
Insert the test probes into the neutral and ground slots. You should get a reading of 0 volts.
warning!
If tests 2 & 3 yield opposite results, it could indicate that the hot and neutral wires are reversed inside the outlet. This must be corrected immediately, as a serious shock hazard exists.
warning!
If the meter reads 0 volts for both tests 2 & 3, it could indicate that the outlet is not connected to ground (lifted ground). This must be corrected immediately, as a serious shock hazard exists.
Test 4.
If tests 1, 2 and 3 read properly, change the meter to read Ohms and select a low range (under 1k ohms). Connect the meter probes between the ground slot and the center screw used to keep the outlet cover in place. The meter should show continuity – 0 Ohms. Make sure the screw is a metal screw, not a plastic insulating one. If the reading is other than 0 Ohms, check to make sure the ground wire in the outlet box is connected to the box.
If you would like to learn more about using your volt-ohm meter, consult "Using Your Meter", published by Master Publishing. TIC Corporation would like to thank them for some of the reference material used here.
Contact
Please Contact us at TIC Corporation where we will be happy to answer any questions you may have.
TIC Corporation will in no way be held responsible for the improper, misuse or unsecured installation of its products. Any and all damage, injury or liability arising from the installation or use of TIC products is the sole responsibility of the original purchaser and final installers.
TIC cannot be held responsible for typographical errors contained within company literature or this website. Pricing and availability subject to change without notice, when placing an order the customer accepts and agrees to all TIC general terms and conditions. Note on pictures shown; all pictures shown for web purposes are low resolution. All TIC products shown are expected to improve or exceed their visual characteristics as shown.