Can you shield a magnetic field?

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

  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.

  Shielding & remediation

• 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.

  Sources & emitters

• Net current (wiring error)

  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.

  Glossary

Sources

1. niehs-emf Electric and Magnetic Fields — National Institute of Environmental Health Sciences. government, link checked 2026-08-12.
2. sbm-2024 Building Biology Evaluation Guidelines for Sleeping Areas (SBM-2024) — Institut für Baubiologie + Nachhaltigkeit (IBN), 2024. ngo, link checked 2026-08-12.