Reg. 559.5.1.206 E.S. Lampholders.

The older style of E27 lamp holder had a metal screw shell into which the lamp screwed. This metal screw shell was readily touched since it was large and often only very slightly recessed into insulating material, also a lamp inserted halfway would have the exposed part of the screw base of the lamp exposed to touch whilst in contact with the outer contact of the holder. Regulations therefore required that the relatively safe neutral conductor was to be connected to the outer or screw shell connector and the much more dangerous line conductor connected to the well recessed center connection.


Newer styles of e27 lamp holder have the threaded part of the holder made of insulating material. The connection to the threaded part of the lamp is made via a small spring contact at the base of this insulated threaded part. The two mains supply connections are therefore of broadly similar size and are recessed to a broadly similar degree.

There is therefore no requirement for any particular polarity in making mains connections to this newer type of E27 lamp holder.


I would still consider it to be better practice to connect the supply neutral to the outer contact, but that is my view of good practice and is not a regulatory requirement. My concern is that with a lamp inserted I don't like the threaded part of the lamp being dangerous to the touch as it is often more accessible than is desirable.

The older style of E27 lamp holder had a metal screw shell into which the lamp screwed. This metal screw shell was readily touched since it was large and often only very slightly recessed into insulating material, also a lamp inserted halfway would have the exposed part of the screw base of the lamp exposed to touch whilst in contact with the outer contact of the holder. Regulations therefore required that the relatively safe neutral conductor was to be connected to the outer or screw shell connector and the much more dangerous line conductor connected to the well recessed center connection.


Newer styles of e27 lamp holder have the threaded part of the holder made of insulating material. The connection to the threaded part of the lamp is made via a small spring contact at the base of this insulated threaded part. The two mains supply connections are therefore of broadly similar size and are recessed to a broadly similar degree.

There is therefore no requirement for any particular polarity in making mains connections to this newer type of E27 lamp holder.


I would still consider it to be better practice to connect the supply neutral to the outer contact, but that is my view of good practice and is not a regulatory requirement. My concern is that with a lamp inserted I don't like the threaded part of the lamp being dangerous to the touch as it is often more accessible than is desirable.