
Understanding Dirty Electricity
Dirty electricity originates from various sources, exists in multiple forms, and is known by several different names (e.g., Line Noise, Dirty Electricity, etc.), but all refer to the same phenomenon: electrical noise in frequencies other than the intended 120V 60Hz wave found on the AC power line.
The power coming out of an AC outlet is a 60Hz pure sine waveform (50Hz in some parts of the world). The electronics you plug into the wall are specifically designed to convert that power into a usable form, such as a 5V DC signal to charge your phone, a 20V DC signal for your laptop, or to leave it as 60Hz AC to directly drive a motor (like an HVAC unit) or a heating element (such as in an oven). As more devices are connected to a circuit, they introduce noise—typically related to power conversion—into the existing 60Hz AC waveform. This noise is a major source of dirty electricity.
A clean AC signal from a power line produces a pure sine wave without artifacts, which looks like this:
A dirty sine wave, however, might appear like this:
How does this happen?
The most common source of dirty electricity in homes is Switch Mode Power Supplies (SMPS). When you plug in a cellphone charger, it takes the 120V 60Hz power from the wall and converts it to 5V DC. SMPS achieve this by constantly switching the input/output power relationship to rectify and step down the voltage. This means they do not draw power in a steady fashion but instead in tiny bursts.
If you examine the output of an SMPS with an oscilloscope, the "clean 5V DC" may reveal noise introduced by the power supply itself:
On the "wall" side of the power supply, this constant switching between minimal current draw and bursts of high current results in SMPS noise modulating on to the 60Hz 120V signal:
The more devices drawing power in this manner, the more "fuzzy" the 120V 60Hz waveform becomes, eventually resembling the "Dirty Sine Wave" image above.
While SMPS are the most common sources of dirty electricity, they are not the only culprits. Here are a few others:
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RF/Radio/Microwave
Wires in walls can act as antennas, allowing RF signals to induce noise onto the power line. For example, using an EM100 Power Line Monitor, you might hear AM radio stations directly on the line. Lower-frequency signals (e.g., ~1MHz for AM radio) can travel much farther than higher-frequency signals (e.g., 2.4GHz Wi-Fi), which are attenuated quickly by the wire’s own inductance and capacitance.
Solar Inverters
Solar inverters convert DC power from solar panels into AC power for the grid. Similar to SMPS, they can introduce noise onto the line. Older, or low-quality inverters produce significant noise, while newer ones, especially those with "True Sine" output, generate minimal interference.
AC Motors
AC motors, such as those in HVAC equipment, refrigerators, and pumps, create noise due to the interaction of their magnetic poles during operation. This interaction can cause both spikes and sinusoidal noise to propagate back onto the AC line.
Why does Dirty Electricity Matter?
Dirty electricity is being studied as a potential source of electromagnetic fields (EMF), which may have associated health concerns.
Beyond health implications, dirty electricity can also disrupt sensitive electronic equipment. For instance, audio gear may pick up line noise, resulting in audible interference through speakers. High-end audio equipment, recording studios, and sensitive lab equipment like oscilloscopes and signal generators often require clean power to function optimally. This is why power filters are commonly used in these settings.
It is also widely accepted that dirty electricity can harm and in some cases shorten the life of sensitive electronics.
Measuring Dirty Electricity
You can verify the presence of dirty electricity using an EM100 Power Line Meter. Any reading over ~50mV indicates enough noise to potentially impact sensitive devices. If you are concerned about health implications, aim to minimize these readings as much as possible.
Mitigating Dirty Electricity
- Identify High-Noise Sources: Measure and isolate devices contributing to line noise. Keep them unplugged when not in use.
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Use Filters: Filters can reduce or block noise on the line. Two types are commonly used:
- Line-to-Ground Filters: Divert dirty electricity to the ground, lowering total noise on the line.
- Blocking Filters: Prevent dirty electricity from reaching sensitive devices but may not reduce overall line noise.
- ⚠️ Note on the "Line Filter EMF Paradox": While line-to-ground filters are effective at reducing line noise, they may inadvertently create localized EMF emissions around the filter itself due to the substantial noise being passed through to the ground. Consider filter location/placement and shielding if this is a concern. Some filters have internal EMI shielding to minimize this impact.
Recommended Filter Manufacturers
Greenwave Filters - Greenwave specializes in filters that are designed to decrease line noise for the purpose of reducing EMF exposure. Greenwave filters consistently filter noise in some of the most challenging environments we've tested.
Audioquest - Audioquest specializes in filters for studio/audio gear that covers filtering, surge protection, and even special cabling to ensure audio gear is getting the cleanest power possible.
Satic USA - SaticShield specializes in home filter/EMF products including line noise filters that both plug in and filters that can be wired directly in to a distribution panel for reducing line noise and associated EMF, flicker free low EMF light bulbs, and EMF shielding materials.
Panamax - Panamax specializes in filters for audio gear including both compact and rackmount varieties. The filters are available with isolated banks, can detect wiring faults, and often have incorporated surge protection.