Henry (unit) Henry (unit) The henry (symbol: H) is the SI derived unit of electrical inductance. If a current of 1 ampere flowing through the coil produces flux linkage of 1 weber turn, the coil has a self inductance of 1 henry.‌ The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England. The inductance of an electric circuit is one henry when an electric current that is changing at one ampere per second results in an electromotive force of one volt across the
Electrical wiring in the United Kingdom 1, 1.5, 2.5, 4, 6 and 10 mm. Sizes of 1 or 1.5 mm are typically used for 6 or 10 ampere lighting circuits and 2.5 mm for socket circuits. The earthing conductor is uninsulated since it is not intended to have any voltage difference from surrounding earthed articles. Additionally, if the insulation of a or neutral wire becomes damaged, then the wire is more likely to earth itself on the bare earth conductor and in doing so either trip the RCD or burn the fuse out by drawing too much current. Earthing and Bonding are used together to provide