Impacts of Poor or Absent Grounding
In an audio system, improper grounding can cause an audible hum, and can significantly reduce the overall noise floor. We are all familiar with dreaded 60 cycle hum, and correctly grounding your equipment helps to significantly reduce its presence. Even worse, poor grounding can cause voltage fluctuations.
The absence of grounding also makes it easier for external sources like radio frequencies and electromagnetic interference to cause undesirable audible effects.
Check Your Main Power Source
Furthermore, it's also worth your while to ensure your main power source, and its circuitry are properly configured and grounded. For example, if your source is a wall outlet in a house, faulty wiring and or grounding can open the door to interference in the signal chain. No matter the quality of your equipment if the root cause is not addressed it can translate to undesirable effects, and possibly even damage. Older houses, especially those built before 1950 are most susceptible to circuitry problems including a faulty or absent ground. Even newer homes can have issues due to degradation over time, damage, and pests. Don’t overlook the integrity of your main power source, because its effects can be detrimental.
Is Your System Properly Grounded?
There are a couple of ways to quickly and safely determine whether or not your house is grounded. First, locate your electrical meter which is usually somewhere on the outside of your home. Like in the picture above, if your electricity is coming from a telephone pole, you will most likely see a wire traveling into the ground along the foundation of the house below the meter. All telephone poles are grounded, and the grounding at your home's meter is essentially an extension of this ground network. If you see this wire it is a sure sign that your home is grounded. This wire is connected to a copper grounding rod that is driven deep into the ground.
You probably will not see this wire if your electric comes in underground. Most modern homes are now built and powered with underground electricity. With modern construction techniques and electrical codes, you can be almost certain that your home is grounded.
If you're still not sure if your home is grounded you can perform a quick test using a multimeter to test the outlets in your home. Configure your multimeter to the highest AC voltage setting. Insert the red probe into the smaller rectangular opening, and the black probe into the larger one beside it. Take note of the voltage reading. Now remove the black probe and insert it into the round ground opening below. If the voltage reading is the same it means the outlet is properly grounded.