Since a certain voltage of electric current is constantly applied to the telephone wiring, increasing when the phone rings, it is dangerous to touch the inside of a junction box or the metal parts connected to it.
Kuna telefonijuhtmetes on pidevalt mõningane elektripinge, mis telefoni helisedes kasvab, siis on ohtlik puudutada harukarbi sisemust või sellega ühendatud metallosi.