# Plug-in line filter (dirty-electricity filter)

> A capacitive filter that shunts high-frequency harmonics on a circuit; effects are circuit-specific, can shift harmonics rather than remove them, and can raise magnetic fields near the filter itself.

- Canonical URL: https://emfbase.com/shielding/line-filter
- Collection: Shielding & remediation
- Record id: `shielding:shielding-line-filter`
- Status: provisional
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/shielding/line-filter
- Also known as: dirty electricity filter, Greenwave filter, Stetzerizer filter

## Key values

- **Form:** filter
- **Targets:** dirty electricity
- **Grounding required:** No

## Failure modes

- Filters draw current, which raises the local magnetic field around the socket they occupy
- Can move harmonic energy to a different frequency band instead of removing it, improving one index while worsening another
- No recognised exposure unit to verify against; the common proprietary index is not an exposure metric
- Fixing the source (dimmer, driver, inverter) is cheaper and permanent

## Related records

- [Dimmer switch and phase-cutting controls](https://emfbase.com/emitters/dimmer-switch): Phase-cutting dimmers chop the mains waveform and inject harmonics from a few kilohertz up to about 1 MHz onto the building wiring — the classic source of what practitioners call dirty electricity.
- [Dirty-electricity (line harmonics) meter](https://emfbase.com/meters/dirty-electricity-meter): Plugs into a socket and reports high-frequency harmonic content riding on the mains, the quantity used to judge dimmers, LED drivers, inverters and switch-mode supplies.

## Sources

- `sbm-2024` Institut für Baubiologie + Nachhaltigkeit (IBN) (2024). *Building Biology Evaluation Guidelines for Sleeping Areas (SBM-2024)*. https://buildingbiology.com/site/downloads/SBM-2024_EVALUATION_GUIDELINES_EN.pdf — ngo, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.