Os rádios mágicos são magicamente modificados.
...many radios have been legally modified by the wizarding community for their own use, which broadcast regular wizarding programmes. The Ministry conceded that Muggles frequently catch snippets of advice on, for instance, how to prune a Venomous Tentacula, or how best to remove gnomes from a cabbage bed, but argued that the radio-listening Muggle population seems altogether more tolerant, gullible, or less convinced of their own good sense, than Muggle TV viewers. Reasons for this anomaly are examined at length in Professor Mordicus Egg’s The Philosophy of the Mundane: Why the Muggles Prefer Not to Know. Professor Egg argues cogently that Muggles are much more likely to believe they have misheard something than that they are hallucinating.
(Pottermore, "Technology").
Portanto, a rede sem fio Wizarding é executada com mágica, não com eletricidade.
Isto é mostrado ainda mais quando a Sra. Weasley controla seu wireless por magia ao invés de usar um controle remoto elétrico ou algo parecido.
They were all supposed to be listening to a Christmas broadcast by Mrs Weasley's favourite singer, Celestina Warbeck, whose voice was warbling out of the large wooden wireless. Fleur, who seemed to find Celestina very dull, was talking so loudly in the corner that a scowling Mrs Weasley kept pointing her wand at the volume control, so that Celestina grew louder and louder.
(Half-Blood Prince, Chapter 16, A Very Frosty Christmas).
No entanto, a restrição ao uso de eletricidade em torno da magia não se aplica a todos os locais mágicos. É mencionado apenas em relação a Hogwarts. Presumivelmente, Hogwarts tem mais "magia no ar" do que a maioria dos outros lugares por causa do grande número de pessoas fazendo magia lá.
"All those substitutes for magic Muggles use - electricity, and computers and radar, and all those things - they all go haywire around Hogwarts, there's too much magic in the air."
(Goblet of Fire, Chapter 28, The Madness of Mr Crouch).
Pode ser que casas domésticas como a Burrow não sejam afetadas por essa restrição.