# Can you shield a magnetic field?

> Almost no common material blocks ELF magnetic fields; mu-metal gives a factor of 2–5 at high cost. Distance and source correction are the real options.

- Canonical URL: https://emfbase.com/questions/can-you-shield-magnetic-fields
- Collection: Direct answers
- Record id: `questions:can-you-shield-magnetic-fields`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/questions/can-you-shield-magnetic-fields
- Also known as: block magnetic field, mu metal shielding, shield power line EMF

## Key values

- **Topic:** shielding

## Question

Can I shield magnetic fields from power lines or wiring?

## Answer

Barely, and rarely economically. Power-frequency magnetic fields pass through nearly all common building materials, including aluminium foil, conductive paint and shielding fabric, so the only materials that help are high-permeability alloys such as mu-metal, which typically deliver a factor of two to five in a real retrofit and lose their properties if bent or drilled. The effective interventions are distance and fixing the source — correcting a net-current wiring fault, relocating a bed away from the service panel, or reducing the current causing the field.

## Related records

- [High-permeability alloy (mu-metal) magnetic shielding](https://emfbase.com/shielding/high-permeability-alloy): The only material class that meaningfully attenuates power-frequency magnetic fields, and even then typically by a factor of two to five in a retrofit — which is why distance and source correction are preferred.
- [High-voltage transmission line](https://emfbase.com/emitters/high-voltage-transmission-line): Fields directly beneath a loaded transmission line reach tens of milligauss and fall off roughly with distance for a balanced three-phase circuit, reaching background at 30–60 m for typical loadings.
- [Net current (wiring error)](https://emfbase.com/glossary/net-current): When the current flowing out on a circuit does not return on the same cable, the imbalance radiates a magnetic field across the whole building.

## Sources

- `niehs-emf` National Institute of Environmental Health Sciences. *Electric and Magnetic Fields*. https://www.niehs.nih.gov/health/topics/agents/emf — government, link checked 2026-08-12
- `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.