Electrical socket imperial screws

[John Miller]

I'm getting some old artex skimmed out in the hall and some of the
electrical socket backboxes are of the old imperial type. I would prefer to
avoid having to change the back box if I need longer screws, but I can't
find anywhere that sells the old BA screws. Is there an easy solution? - I
thought about trying to tap the threads, but not sure if this is likely to
work.

[Matty F]

On Jul 15, 12:50 pm, "John Miller" <millerhouse.s...@talktalk.net>
wrote:

You may be able to find a metric or Whitworth screw that is close
enough. What is the approximate diameter and threads per inch?

Type Size Dia Inch TPI Dia mm Pitch mm
BA 3 0.1614 34.84 4.10 0.73
M 4.5 0.177 33.87 4.5 0.75
BA 2 0.185 31.35 4.70 0.81
BSF 3/16 0.1875 32 4.76 0.79
BSW 3/16 0.1875 24 4.76 1.06
MF 5 0.197 50.80 5 0.5
M 5 0.197 31.75 5 0.8
BA 1 0.2067 28.25 5.25 0.90
BSW 7/32 0.21875 24 5.56 1.06
BSF 7/32 0.2188 28 5.56 0.91
BA 0 0.2362 25.38 6.00 1.00
MF 6 0.236 33.87 6 0.75
M 6 0.236 25.40 6 1

[Edgar Iredale]

John Miller wrote:

Namrick sell some B.A. items.
http://www.namrick.co.uk/acatalog/Home_B_A__Machine_Screws_183.html

Edgar

[NT]

On Jul 15, 1:50 am, "John Miller" <millerhouse.s...@talktalk.net>
wrote:

tapping the threads is easy and works ok.

NT

[Dave Liquorice]

On Wed, 14 Jul 2010 21:18:46 -0700 (PDT), Matty F wrote:

> What is the approximate diameter and threads per inch?

Accessory screws are M3.5, I'm surprised that the OP can't find BA
screws. Plenty of seller hits when googling...

OK you won't find them in the DIY sheds but I'd have thought a decent
electrical wholesaler might, more likely to find a little hand held
M3.5 tap though. 6BA is 0.11 inch (2.794mm) so the hole can simply be
tapped out.

--
Cheers
Dave.

[stuart noble]

I think I've seen a sparks using a simple hand tool to do this.

[Bob Minchin]

like this

http://www.tlc-direct.co.uk/Products/BHM3dot5.html

Bob

[Andy Dingley]

On 15 July, 10:19, stuart noble <stuart_no...@ntlworld.com> wrote:

> I think I've seen a sparks using a simple hand tool to do this.

Although quite expensive. Mine is just a 3.5mm tap, a cheap file
handle and some epoxy.

[NT]

Thats what I've got. No predrilling needed, just use the tap once and
its done.

NT

[John Rumm]

Yup, most electrical wholesalers will sell you something like:

http://www.tlc-direct.co.uk/Products/BHM3dot5.html

--
Cheers,

John.

/=================================================================\
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[The Natural Philosopher]

I thought that this was the case, but forebore giving what might be bad
advice.

many electricians carry just such a tap: I assumed it was to sort out
stripped or tight threads, but maybe it is quire often necessary when
working on older installations.

[dave]

Mine is a tap and a large chocky block section. It was given to me
mumble, mumble years ago.

Dave

[Ian French]

"John Miller" <millerho...@talktalk.net> wrote in message
news:i1lm01$ree$1...@news.eternal-september.org...

>Screwfix also do the 3.5mm Tap in a handle that will do the job fine.

http://www.screwfix.com/prods/94356/Hand-Tools/Screwdrivers/Bradawls-Countersinks/Ruko-Socket-Re-Threader-3-5mm

Ian.

[John Miller]

"Ian French" <ia...@dsl.pipex.com> wrote in message
news:kdydnUWQSKraqqLR...@pipex.net...

Thanks to all who replied. I was looking for the specific domed head screws,
but hadn't considered that plain BA screws would do just as well. Senior
moment! May try the tap solution though as this seems to be the favoured way
to go.

John Miller

[Dave Plowman (News)]

In article <i1o7ci$ufu$1...@news.eternal-september.org>,

John Miller <millerho...@talktalk.net> wrote:
> Thanks to all who replied. I was looking for the specific domed head
> screws, but hadn't considered that plain BA screws would do just as
> well. Senior moment! May try the tap solution though as this seems to
> be the favoured way to go.

Think the actual name is 'raised head' IIRC and yes, they are near
impossible to find - especially in the original finish which might be
chrome or bronze, etc. However a countersunk head BA one will work just
fine.

The other alternative to re-tapping the threads on a steel back box is to
enlarge the hole to clearance for a metric screw and superglue a nut to
the back of the lug. But you won't find nuts in the average DIY place.

--
*When cheese gets its picture taken, what does it say? *

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

[Mike Clarke]

Dave Plowman (News) wrote:

> The other alternative to re-tapping the threads on a steel back box is to
> enlarge the hole to clearance for a metric screw and superglue a nut to
> the back of the lug. But you won't find nuts in the average DIY place.

And connect a link between the earth terminals on the back box and the
socket since the superglue means that you won't be able to rely on earth
continuity through the fixing screws.

--
Mike Clarke

[Dave Plowman (News)]

In article <UdqdnZxyRrOvvd3R...@brightview.co.uk>,

You never rely on that connection anyway. Screws can come loose. Corrosion
can occur. Etc.

--
*Parenthetical remarks (however relevant) are (usually) unnecessary *

[Dave Liquorice]

On Fri, 16 Jul 2010 10:02:42 +0100, Mike Clarke wrote:

> And connect a link between the earth terminals on the back box and the
> socket since the superglue means that you won't be able to rely on earth
> continuity through the fixing screws.

The regs haven't allowed that for a while. Link required from backbox
to accessory.

--
Cheers
Dave.