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Andrew Gabriel

In article ,
writes:
For your perusal...

A '''pattress''' is the box that sits behind electrical sockets and

As others already said, that's the wrong word. I think "back box"
is the most commonly used term, for both surface and flush fitting.

switches. Pattresses come in metal and plastic, and in surface mount
and flush versions.

==Pattress types==

===Metal flush mount pattress===
[[image:Pattress metal 406-3|thumb]]
Metal recessed pattresses are used to mount sockets & switches flush
to a solid wall. A recess is chiselled out for the pattress to sit in.
Knockouts are provided for [[cables|cable]] entry. These are the most
common domestic pattresses.

===Plastic surface mount pattress===
[[image:Pattress dbl 759-4.jpg|thumb]]
Plastic surface mount pattresses are used for electrical accessories
that sit on the surface of walls. The pattress is [[screw]]ed in
place, and knockouts are provided for [[cables|cable]] entry, either
via the sides or the rear.

Surface mount types are available in square or rounded corners to
match different wiring accessory styles.

These are available in different depths. The shallowest ones are
suitable for light switches where no screw block connections need to
be made behind the switch. Deeper ones are usually used for sockets,
but fitting sockets into shallow patresses is often possible, if
tight, and light switches with a few screw block connections behind
them will need the deep ones too.

That paragraph applies to all types, and wants to be at a higher
heading level.

Plastic surface mounting patresses are the 2nd most common domestic
type.

===Stud wall pattress===
[[image:Pattress PB 757-5.jpg|thumb]]
Plasterboard boxes are used to flush mount switches etc to [[Sheet
Materials|plasterboard]]. The picture shows the position of the grips
before and after fitting.

===Architrave pattress===
[[image: |thumb]]
Architrave pattresses are used with little architrave switches.

and Klik lighting sockets.

===Metal surface pattress===
[[image:Metal skt & pattress 754-7.jpg|thumb]]
Metal surface pattresses aren't very common in homes. They are used
with metal accessories, and are ideal for workshops (and other
environments) requiring particularly tough accessories.

For proper fitting of the wiring accessory, the back box and
accessory should be matched from the same range.

===Twin single pattress===
[[image:Twin pattress 849-4.jpg|thumb]]
Twin pattresses are designed to take two single accessories. These are
used when 2 different accessories in one position are wanted. These
are not the same size as a double pattress.

They can only be used with standard 86mm square accessories.
Other accessory styles won't fit.

===Non-standard pattress===
[[image:Pattress ashley 758-5.jpg|thumb]]
Non standard pattresses are sometimes seen. These generally don't fit
standard sockets. They're designed to achieve some advantage, such as
styling or compact size.

===3 & 4 gang pattress===
[[image: |thumb]]
3 way socket convertors use a pattress designed to [[screws|screw]]
onto the top of an existing single flush mount pattress. These turn a
1 way flush socket into a 3 way surface mount socket. Sometimes the
[[cables]] aren't long enough and need extending.

4 way socket convertors...

===Grid switches===
[[image:...]]
Grid switch pattresses are another type not often seen in homes. These
accept a number of accessories, which can be mixed at will in the one
pattress. Available accessories include various switches, dimmers, key
switches, indicators, etc. The accessories don't have any face plate,
a single full size faceplate is fitted last. MK is known for its grid
switch range.

==Junction boxes==
[[image: |thumb]]
[[Cables]] are often joined in pattresses, but their purpose is for
mounting switches and sockets. When a container is wanted only for
joining cables, a junction box is smaller & cheaper.

==Thermoplastic and Thermoset==

Better to use the full terms Thermosoftening and Thermosetting.

[Just about to reboot computer to upgraded OS, so I'm sending
as far as I got -- might read the rest later]

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]