In article
,
wrote:
2. Backbox - again widely used but not universal, plus there's no
shortage of other things it can also mean

What - in electrical terms?

There's nothing that limits it to electrical afaics, so its wide open.

Then the whole idea is pointless.

And within electrical it might refer to a junction box, a small CU,
and assorted items that arent part of house wiring.

Are these more obscure terms?

Plenty of electrical bits and pieces consist of a plate of some sort which
fits a box. But with all the JBs and CUs I've seen the 'guts' are in the
box rather than on the plate.

NT

--
*I never drink anything stronger than gin before breakfast *

Dave Plowman London SW
To e-mail, change noise into sound.

On Aug 26, 5:44*pm, "Dave Liquorice"
wrote:
On Tue, 26 Aug 2008 04:37:55 -0700 (PDT), wrote:
So far we've got 3 choices:

1. Pattress
2. Backbox
3. Electrical accessory wiring box

The issues around the name(s) can be mentioned/discussed in the
article so no-one is left in confusion - that would be best whatever
title we use.

How does the disambiguation feature of a wiki work? *I've not played with
that at all.


Disambig can be either its own separate page or a section in a page.
In this case the latter seems more suitable, since its unlikely we'd
have a page for the other pattresses any time this year

When I get time I'll do all the work and re-draft the article


NT

In uk.d-i-y, The Medway Handyman wrote:
Dave Liquorice wrote:
On Sat, 23 Aug 2008 17:59:54 -0700 (PDT), wrote:

For your perusal...


A '''pattress''' is

Possibly not a word. At least my Concise OED doesn't have it (the
online OED is subscription) niether do a couple of other online
dictionaries. There is a wikipedia entry but that is wikipedia, pass
the salt, thank you.

However I have used the word, so it does "exist" but I use it to mean
a multiple outlet flex mounted trailing socket. What this article
describes I would call a "back box".

If you search the TLC Direct site for 'pattress' you get a list of surface
mounted boxes in various finishes, but no plasterboard or metal boxes. Dry
lining/plasterboard & metal are referred to as simply 'boxes' and respond to
the search for 'back box' or 'box'.

That corresponds to my usage and the usage of people that I deal with
here in Cheshire. Surface fittings have pattresses. Flush fittings have
back boxes. It's a simple and useful distinction.

--
Mike Barnes

On Aug 24, 1:59*am, wrote:
For your perusal...

Hopefully the final draft now, with lots of input added...


'''Pattress''' usually means the box that sits behind electrical
sockets and switches, though it has other meanings too. Modern
electrical pattress boxes come in metal and plastic, and in surface
mount and flush versions.


==Uses of the word 'pattress'==
'Pattress' has more than one meaning in DIY. Its also a word whose
meaning has changed relatively quickly over time, resulting in
significant disagreement over which meanings are correct.

===History===
[[image:Socket_(__)_785-4.jpg|thumb|old wood pattress plate]]

Pattress is derived from the latin 'pateras' meaning a shallow bowl or
plate.

In the 1800s 'pattress' was used to mean the flat wooden plates that
gas lighting equipment was mounted on.

In the 1930s electrical accessories were mounted on wooden plates, and
these were mainly referred to as 'pateras.' The anglicised version
'pattress' gradually took over from pateras.

When wiring regs required electrical accessories to be housed in
fireproof containers, a box was used between the wooden pateras and
socket, instead of mounting it directly to the pateras. This was known
as a pattress box. Over time this became known as a pattress.

Today many trade and DIY people refer to any electrical backbox as a
pattress. There are also many that consider only surface mount boxes
to be pattresses, and many that don't call any type of backbox a
pattress. Unfortunately this is equally true of the other names for
these things, so we just have to be aware of the differing usage of
the term.

The electrical boxes used behind sockets and switches are variously
known as pattresses, wiring accessory boxes, boxes, and backboxes,
with none of these terms being universal.


===Non-electrical pattresses===
The word 'pattress' also describes flattish iron plates used for load
spreading, as used to tie houses with structural defects together.



==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 [[screws|screwed]]
in place, and knockouts are provided for [[cables|cable]] entry,
either via the sides or the rear.

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.

Plastic surface mounting patresses are the second 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===
Architrave pattresses are used with little architrave switches.


===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.


===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.


===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===
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===
(pic wanted)
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
box. 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.


===Round conduit boxes===
Round boxes forming part of a conduit system are sometimes seen in
houses, though not often.


==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.

==Depth==
Plastic surface pattresses are widely available in different depths,
ranging from 16mm (mainly for switches) to 47mm (mainly for sockets).

Other types of pattress are also found in different depths, but less
often.


==Thermoplastic and Thermoset==
[[image: |thumb]]
Plastic pattresses intended for mains use are made from thermoset
plastics, mainly white bakelite. These don't soften when hot, and act
as a fire resistant container.

Similarly sized pattresses intended for phone networks are generally
made from thermoplastics. These come in more than one size, the larger
of which fits mains sockets. These can be bent slightly by hand, so
are easily recognised. They offer no heat or fire protection and don't
meet modern safety requirements for mains use.


==Style & fit==
[[image:Pattress corner detail Egatube & Tenby 850-4.jpg|thumb|Egatube
vs Tenby]]
Different brands of pattress have different corner detailing, intended
to match their own brand of accessories. Standard pattresses, switches
and sockets of different brands can be freely mixed, but the
difference in corner detailing can make a minority of combinations
look wrong. If mixing brands its best to check they look right
together before buying.

Non-standard pattresses can't be expected to fit standard sockets.

===Metal accessories===
[[image:Socket metal misfit 807-6.jpg|thumb|Oops!]]
Many metal accessories for surface mounting are a different size to
plastic pattresses. The screw spacing is the same, but the outer size
isn't. These are an eyesore if one type is fitted to the other.

This problem doesn't occur with the various retrofit metal accessories
on the market designed to fit standard plastic pattresses (and
recessed metal ones). It only applies to the traditional functional
metal sockets & backboxes.


==Breakage==
[[Screws]] holding plastic pattresses in place should be done up until
the screwhead touches the pattress surface, and no more. Any further
tightening is likely to break the brittle plastic.

Budget brand plastic pattresses can suffer a significant breakage rate
during installation, particularly if a fair amount of hole needs to be
made for [[cables|cable]] entry, or if the underlying wall is not
competely flat, or the installer doesn't appreciate their frailty.


==Earth connection==
Metal pattresses have an earth terminal for connecting to the circuit
earth. A sleeved wire should be run from the socket earth terminal to
the backbox.


===2 core wiring===
A small minority of houses still have old 2 core [[lighting]]
circuits. Metal pattresses or accessories should not be fitted to such
circuits due to the absence of anything more than functional
insulation as protection against shock.

Sometimes people fit them and borrow an earth from a nearby socket
circuit. This works but its not considered best practice, as there's
always the possibility of the socket circuit being decommissioned
later, leaving the [[lighting]] accessories unearthed. Hence its not
wiring regulations compliant.

Plastic pattresses and accessories are the only type recommended for
these circuits. However that doesn't imply that fitting them is always
safe; some [[Historic Mains Cables|historic rubber wiring]] is so
badly perished that moving the wires during fitting is sometimes a
sizeable risk. If perishing is limited to just the wire ends, sleeving
may be fitted to replace the function of the damaged insulation.


==Extension leads==
Surface pattress boxes are not designed for use on extension leads.
They have no cordgrip, and are brittle, which is not ideal for
portable use. Despite this they see fairly widespread use in extension
leads, so we will describe how to make these not-recommended leads as
safe as possible.

The main problem is the lack of cordgrip. There are 4 ways to
implement a cordgrip.
# Knockout 3 of the knockouts in a row on one side/top/bottom of the
pattress, and thread the lead through all 3 in a zigzag pattern. This
makes a fully effective cordgrip.
# The pattess box can be mounted on a piece of wood and a cordgrip
from a mains plug used to secure the lead inside the box. The 2 screws
go into the backing wood.
# Knotting the wire is sometimes used, but this is only partially
effective.
# A few surface pattress boxes do have cordgrips (eg Marbo).

Breakability can be reduced to some extent by mounting the pattress
box on a piece of chipboard that's larger all round than the box.
Chipboard and MDF are best as they're soft enough to reduce peak
impact forces.


==See Also==
* [[:Category:Electrical]]
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:Electrical]]


NT

wrote in message
...
On Aug 24, 1:59 am, wrote:
For your perusal...


what are those white plastic spacers that can (Could) be bought to
effectively increase the depth of a box by bringing the wiring accessory
forward about 6mm?

In article ,
John wrote:
what are those white plastic spacers that can (Could) be bought to
effectively increase the depth of a box by bringing the wiring accessory
forward about 6mm?

IIRC, called mounting frames.

--
*Sometimes I wake up grumpy; Other times I let him sleep.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sep 18, 11:04*am, "Dave Plowman (News)"
wrote:
In article ,
* *John wrote:

what are those white plastic spacers that can (Could) be bought to
effectively increase the depth of a box by bringing the wiring accessory
forward about 6mm?

IIRC, called mounting frames.

Added, thanks. Just got the images to sort out now.


NT

wrote in message
...
On Sep 18, 11:04 am, "Dave Plowman (News)"
wrote:
In article ,
John wrote:

what are those white plastic spacers that can (Could) be bought to
effectively increase the depth of a box by bringing the wiring accessory
forward about 6mm?

IIRC, called mounting frames.

Added, thanks. Just got the images to sort out now.


NT

Thanks - I was trying to refer to one recently but didn't know the name and
couldn't find them.

http://www.tlc-direct.co.uk/Products/MKK2134.html

Would you say that using one as a spacer for (say) a deeper accessory is
legitimate?

On Sep 18, 8:37*pm, "John" wrote:
wrote in message

...
On Sep 18, 11:04 am, "Dave Plowman (News)"
wrote:

In article ,
John wrote:

what are those white plastic spacers that can (Could) be bought to
effectively increase the depth of a box by bringing the wiring accessory
forward about 6mm?

IIRC, called mounting frames.

Added, thanks. Just got the images to sort out now.

NT

Thanks - I was trying to refer to one recently but didn't know the name and
couldn't find them.

http://www.tlc-direct.co.uk/Products/MKK2134.html

Would you say that using one as a spacer for (say) a deeper accessory is
legitimate?

I've never used them - didnt even know they existed. I expect someone
else here has more experience of them


NT

In article ,
John wrote:

wrote in message
...
On Sep 18, 11:04 am, "Dave Plowman (News)"
wrote:
In article ,
John wrote:

what are those white plastic spacers that can (Could) be bought to
effectively increase the depth of a box by bringing the wiring
accessory forward about 6mm?

IIRC, called mounting frames.

Added, thanks. Just got the images to sort out now.


NT

Thanks - I was trying to refer to one recently but didn't know the name
and couldn't find them.

http://www.tlc-direct.co.uk/Products/MKK2134.html

Would you say that using one as a spacer for (say) a deeper accessory is
legitimate?

Yes - although you'll have to modify it somewhat. They have normal 2.5mm
fixing threads - so if you wish to put it between accessory and backing
box you'll need to drill them out. You may also need to remove the spare
'lugs' as these can interfere with some fittings.

It will look a bodge, though.

--
*I'm not as think as you drunk I am.

Dave Plowman London SW
To e-mail, change noise into sound.

The message
from "Dave Plowman (News)" contains these words:


Would you say that using one as a spacer for (say) a deeper accessory is
legitimate?

Yes - although you'll have to modify it somewhat. They have normal 2.5mm
fixing threads - so if you wish to put it between accessory and backing
box you'll need to drill them out. You may also need to remove the spare
'lugs' as these can interfere with some fittings.

It will look a bodge, though.

For a start, the machine screws are M3.5 -- that is the normal variety
for electrical boxes

You're not usually expected to drill them out but rather to use one set
for mounting the spacer and the other set for mounting the accessory.
Of course that sometimes causes problems of orentation and fitting of
some accessories.

In article ,
Appin wrote:
Would you say that using one as a spacer for (say) a deeper accessory is
legitimate?

Yes - although you'll have to modify it somewhat. They have normal
2.5mm fixing threads - so if you wish to put it between accessory and
backing box you'll need to drill them out. You may also need to remove
the spare 'lugs' as these can interfere with some fittings.

It will look a bodge, though.

For a start, the machine screws are M3.5 -- that is the normal variety
for electrical boxes

Indeed.

You're not usually expected to drill them out but rather to use one set
for mounting the spacer and the other set for mounting the accessory.

Most will tend to get used with plaster depth boxes which have only two
fixing lugs.

And you're not 'expected' to use them for this purpose - they're for
mounting a standard accessory to trunking etc. Use as a spacing frame is a
secondary one.

Of course that sometimes causes problems of orentation and fitting of
some accessories.

Some boxes also have only one adjustable lug - which most would fit so it
can be used for horizontal fixing. See also my point about the large
plastic lugs at the top fouling some dimmers, etc.

--
*People want trepanners like they want a hole in the head*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

And you're not 'expected' to use them for this purpose - they're for
mounting a standard accessory to trunking etc. Use as a spacing frame is a
secondary one.

ah, well if you use the things designed for the purpose of extending a
backbox rather than those designed for conduit, it all works much better
- the same screws just fit through the unthreaded lugs on the extender
and go into the original back box:

http://cpc.farnell.com/PL08925/elect...us0?sku=bg-818



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
John Rumm wrote:
And you're not 'expected' to use them for this purpose - they're for
mounting a standard accessory to trunking etc. Use as a spacing frame
is a secondary one.

ah, well if you use the things designed for the purpose of extending a
backbox rather than those designed for conduit, it all works much better
- the same screws just fit through the unthreaded lugs on the extender
and go into the original back box:

http://cpc.farnell.com/PL08925/elect...us0?sku=bg-818

Right - never seen those. Not that I'd be looking for them anyway. ;-)

--
*If all the world is a stage, where is the audience sitting?

Dave Plowman London SW
To e-mail, change noise into sound.

The message
from "Dave Plowman (News)" contains these words:


Some boxes also have only one adjustable lug - which most would fit so it
can be used for horizontal fixing.

And many boxes have -- or at least in the past had -- no adjustable lugs :-(


See also my point about the large
plastic lugs at the top fouling some dimmers, etc.

Been there, done that, got the t-shirt. Often :-(


Whilst they may still be current catalogue items, I think we're dealing
with something which is largely a relic of the past. I dare say I could
probably find one or two in a box of old bits somewhere around my
storeroom, but then I could also find a few packets of mounting flanges.
Remember them? Used to use them on 4 lug single-gang metal back boxes.
Fix flange to box using two of the lugs, then fix box to skirting by
woodscrews through the face of the flange. A whole lot simpler ( and
easier to align) than screwing through the side of the box into the
thickness of the skirting. But then flange boxes became readily
available and the problem was solved in a different and simpler way.