>When was the ES27(?) lampholder introduced
>to your country?.

When bulbs were introduced. Guess why it is called Edison? [Linked Image]

>What types of fittings are they predominantly used in?.(Currently)

All large fittings that take bulbs. (Including mercury lamps) The smaller ES14 is also popular. (In a few cases bayonet cap sockets are used as they're non standard, preventing theft.)

Only fittings intended for low-energy lamps of various types use special holders. These lamps are often horribly expensive.

>What is the maximum wattage of lamp, allowed
>in your fittings using these lampholders?.

Plastic: 60W

>Are there Regulations to require that the
>Phase wire, goes to the centre terminal of
>the l/holder?.

No. For wall mounted switches, you are required to switch the phase wire, not the neutral. (You may of course switch both if you want to.)

[This message has been edited by C-H (edited 11-26-2002).]