Wiki: Pattress

[meow2222]

For your perusal...

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

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 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.

===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=== [[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== [[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, and will look an eyesore if fitted to each 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).

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

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 usually have an earth terminal for connecting to the circuit earth.

===2 core wiring=== A small minority of houses still have 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.

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.

==See Also==

• [[:Category:Electrical]]

• [[Special:Allpages|Wiki Contents]]

• [[Special:Categories|Wiki Subject Categories]]

[[Category:Electrical]]

[Martin Crossley]

SNIP

Some 1960s metal back-boxes had nylon inserts for the (4BA) screws. The screws are thus insulated. They are fine as long as any replacement switches are plastic and re-use the original screws.

[Dave Plowman (News)]

It's also possible to buy fittings with plastic plugs which fit into the screw holes thus insulating them. IIRC Some Wicks ones are like this.

[Dave Liquorice]

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 google pattress in the UK you get about 30,000 hits, some refering to wall tie plates (the large metal plates used to spread the load on a wall when ties are threaded through the building to stop it falling down).

[Rod]

Dreadful Wiki entry.

A pattress is, IMHO, the plate used *behind* a switch, socket, sconce (or similar). Typically early pattresses were wood, often had a 'sculpted' edge (to match the cornices :-) ) and were usually varnished.

Obviously, more recent usage has covered more things, but it is still not a back box. And surely "pattress box" should only apply to a surface mount box which could indeed be sensibly mounted onto a pattress - and never a standard galvanised in-wall type?

AIUI, the pattress did the following:

o Covered up an unsightly hole in the plaster - much more difficult in the days before Polyfilla. And to hide any future cracking imnmediately around a hole in said plaster. Especially important as early installations would very often have been into existing buildings and minimising any requirement for redecoration would have been important.

o Allowed any suitable fixing to be used between the pattress and the wall (and possible gave enough area for two screws which might not have been possible with some of the small switches used in early installations) - but left the fixing between the switch and the pattress to be standardised.

o Stopped the edges of a small switch from digging into soft-ish plaster.

o Stopped the switch from being screwed onto an uneven surface where it would be easy to overstress it as the screws are tightened or in later use.

o Reduced the visual impact of a switch just stuck on the wall - it must have looked very odd before they were common.

o Gave somewhere for cable to turn (if it was being surface mounted).

Given they were used for gas as well, it might have had specific purposes in that context.

Your use seems to make perfect sense if you consider that people have often been seen making extension cables with ordinary sockets/socket boxes mounted onto a bit of wood.

Wow! - you can *still* get wooden gas pattresses:

Yet again - common words largely ignored by dictionaries. So many trade-related words simply have not made it into them - even if they exist in the OED database.

[The Medway Handyman]

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'.

Search SF for 'pattress' and all types of boxes result.

I think the wiki should use the terminology in most common use, rather than the absolutely correct terminology.

[Dave Plowman (News)]

Yes - go into any wholesaler in London and you'd get a blank look if asking for a pattress. And from my spell checker. ;-)

My opinion is it was those wood plates older surface mounted switches were fixed to. So the nearest modern equivalent would be those rare spacers which go between backing box and fitting - sometimes called mounting frames.

I'd stick to backing box - that qualified by the material, size and type will get you what's needed anywhere Like metal flush 35mm 2 gang backing box

[meow2222]

You can still buy wooden electrical pattresses too.

Dictionaries are very useful tools, but are a bit overestimated imho. Another example is 'anonymous' which dictionaries generally describe as having no name, when usually it means declaring no name, which isnt the same.

I'll do a bit more writing when I get the time, cheers everyone

NT

[Andrew Gabriel]

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.

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

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

and Klik lighting sockets.

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

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

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]

[Norman Billingham]

The full OED defines pattress as "A wooden or plastic block attached to a surface to receive a gas bracket, electric light switch, ceiling rose, etc.; the base of a wall socket."

Dates back to 1886 according to the OED, when it was a block for mounting a gas fitting. They quote 1969 A. J. COKER Electr. Wiring (ed. 7) v. 81 "Pattress boxes are also available to convert flush-type to surface mounting"

I've certainly always believed a pattress was surface mounting and I've never used the term to mean a flush mounting box. But then dictionaries reflect usage they don't create it.

[Dave Plowman (News)]

I think the problem is that the current pattress meaning is a regional thing. So best avoided in an FAQ - unless fully explained. When dealing with suppliers it's best to avoid jargon unless you're certain they'll know what you mean.

[John Rumm]

[John Rumm]

"Electrical accessory mounting boxes" might be simplest, with back box, pattress, dry lining box etc defined within and perhaps as redirects to the article.

[Andy Wade]

The etymology it gives is interesting too: "Probably an alteration of classical Latin pateras, plural of PATERA n. (compare quot. 1905 at main sense)."

And the entry for PATERA is: patera, n Plural pateræ, pateras. Forms: 16- patera, 18 pattera. [< classical Latin patera broad shallow bowl or dish, perhaps < the same Indo-European base as ancient Greek {pi}{alpha}{tau}{gaacu}{nu}{eta} (see PATEN n.).

I agree entirely. I'd go further and say that the term should be avoided altogether unless referring to the wooden blocks or moulded mounting plates used in old wiring systems. For modern accessories "flush mounting box" and "surface mounting box" are clear and unambiguous.

Yes but... (... but we probably don't want the Queen of Hearts defining technical vocabulary.)

[meow2222]

Yes, lets just be practical about it. Lots of diyers, tradespeople and sellers call them pattresses, so pattress is a valid name for them. Ditto backboxes, ditto wiring accessory boxes.

I could very easily be mistaken on this, but I thought the use of 'pattress' for moden backboxes was the result of the continuing to use the word for the bit that goes behind a socket, even though today the box shape of it is different to the old flat plates. Hence 'pattess' describes 3 different things today - backboxes, the older little wooden plates, and big structural loadpsreading plates - but for the most part, electrical accessory backboxes.

I dont think any one particular term as an article heading is going to be a winner, as none are in universal use, and all are terms in widepsread use.

PS if anyone can supply a pic of an architrave pattress and 3 & 4 way boxes, please do.

NT

[Andy Champ]

Just to add my 2p worth, I've always called them "Pattress Boxes". But then, the guy who taught me was from Queensland - so it could be a regional thing.

Andy

[Dave Liquorice]

True but I think pattress is not widely understood or particularly clear.

I've never heard the word used in that way. B-)

From the wiki point of view and using the title in other articles "Electrical accessory mounting boxes" is a bit of a handful and is a plural so if the article that wants to use it is talking singular you have to step through a hoop...

I think "Wiring Accessory Box" is the best as it says what it is in a fairly generic way. Pattress really needs it's own page to describe the old use as the mounting blocks for gas and electrical fittings, the use as load spreading plates in building ties, etc, and a link to the Wiring Accessory Box article. Redirects from "Back Box", "Flush Mounting Box", "Surface Mounting Box" to, preferably the relevant section, of the Wiring Accessory Box article would be useful.

[Tanner-'op]

Dave,

I was told to call surface mounted boxes for sockets/light switches etc "patress boxes" by electricians from the time I started my apprenticeship as a chippie way back in 1964 - and every electrician and electrical supplier in my neck of the country has called them that - and are still doing so.

Tanner-'op

[John Rumm]

[John Rumm]

I most commonly come across the term pattress used only for surface mounting boxes.

I expect there is a regional variation, but its certainly not the most commonly used of the terms.

Agreed - something generic for the article title would hence be best.