Donate to Remove ads

Got a credit card? use our Credit Card & Finance Calculators

Thanks to waiting4godot,yyuryyub,88V8,Anonymous,Fluke, for Donating to support the site

Double sockets - switches on the outside

Does what it says on the tin
pochisoldi
Lemon Slice
Posts: 933
Joined: November 4th, 2016, 11:33 am
Has thanked: 31 times
Been thanked: 456 times

Double sockets - switches on the outside

#644897

Postby pochisoldi » February 5th, 2024, 3:05 pm

While shopping for double sockets, and I noticed that MK offer double sockets with switches on the outside rather than next to each other on the inside (which appears to be the norm).

Other than the (to me) obvious "so you don't accidentally turn the other switch on or off", are the there any other uses for these sockets?
Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?

PochiSoldi

Urbandreamer
Lemon Quarter
Posts: 3039
Joined: December 7th, 2016, 9:09 pm
Has thanked: 340 times
Been thanked: 1000 times

Re: Double sockets - switches on the outside

#644904

Postby Urbandreamer » February 5th, 2024, 3:34 pm

pochisoldi wrote:While shopping for double sockets, and I noticed that MK offer double sockets with switches on the outside rather than next to each other on the inside (which appears to be the norm).

Other than the (to me) obvious "so you don't accidentally turn the other switch on or off", are the there any other uses for these sockets?
Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?

PochiSoldi


While technically impossible to say, the double sockets that I have linked to are VERY different electrically.

https://www.electricpoint.com/mk-logic- ... white.html
(switches on the outside, but more important a different earthing arrangement)
https://www.electricpoint.com/mk-logic- ... white.html
(switches on the inside, but a standard earthing arrangement)

It could be a simple convention so that the electrical difference can be told at a glance.

This one also has a special earthing arrangement, though different from the first.
https://www.electricpoint.com/mk-logic- ... board.html
Again, switches on the outside.

Hallucigenia
Lemon Quarter
Posts: 2522
Joined: November 5th, 2016, 3:03 am
Has thanked: 163 times
Been thanked: 1668 times

Re: Double sockets - switches on the outside

#644961

Postby Hallucigenia » February 5th, 2024, 7:18 pm

pochisoldi wrote:Other than the (to me) obvious "so you don't accidentally turn the other switch on or off", are the there any other uses for these sockets?
Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?


One obvious scenario is that it makes the switches much more accessible if you have something bulky plugged into both sockets, like 3-way blocks or transformers.

servodude
Lemon Half
Posts: 8177
Joined: November 8th, 2016, 5:56 am
Has thanked: 4378 times
Been thanked: 3524 times

Re: Double sockets - switches on the outside

#645013

Postby servodude » February 6th, 2024, 1:32 am

Hallucigenia wrote:
pochisoldi wrote:Other than the (to me) obvious "so you don't accidentally turn the other switch on or off", are the there any other uses for these sockets?
Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?


One obvious scenario is that it makes the switches much more accessible if you have something bulky plugged into both sockets, like 3-way blocks or transformers.


With the caveat that it makes it harder to plug bulky things in in the first place

modellingman
Lemon Slice
Posts: 610
Joined: November 4th, 2016, 3:46 pm
Has thanked: 591 times
Been thanked: 360 times

Re: Double sockets - switches on the outside

#645014

Postby modellingman » February 6th, 2024, 2:05 am

pochisoldi wrote:While shopping for double sockets, and I noticed that MK offer double sockets with switches on the outside rather than next to each other on the inside (which appears to be the norm).

Other than the (to me) obvious "so you don't accidentally turn the other switch on or off", are the there any other uses for these sockets?
Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?

PochiSoldi


See Approved Document M
volume 2 at https://www.gov.uk/government/publicati ... document-m which deals with accessibility in non-residential buildings. In particular, paragraph 4.29 states in the context of design considerations for switches, outlets and controls that

It is also an advantage if individual
switches on panels and on multiple socket
outlets are well separated, or in the form of
large touch plates, to avoid the inadvertent
selection of an adjacent control by visually
impaired people and people with limited
dexterity.


Positioning the switches on a switched double socket towards the outside edge meets the "well-separated" criterion.

modellingman

csearle
Lemon Quarter
Posts: 4709
Joined: November 4th, 2016, 2:24 pm
Has thanked: 4718 times
Been thanked: 2039 times

Re: Double sockets - switches on the outside

#645195

Postby csearle » February 6th, 2024, 8:39 pm

Urbandreamer wrote:While technically impossible to say, the double sockets that I have linked to are VERY different electrically.
Whilst not wanting to be combative, they are not really very different electrically. They are almost the same. They just have two Earths instead of one. If you leave linked the two Earth terminals they have the same function as conventional sockets as explained here.

I may be wrong but I think only plugs with special T shaped Earth pins will fit, thus continuing the two seperate Earths through into the equipment. Happy to be corrected on this though. C.

Urbandreamer
Lemon Quarter
Posts: 3039
Joined: December 7th, 2016, 9:09 pm
Has thanked: 340 times
Been thanked: 1000 times

Re: Double sockets - switches on the outside

#645244

Postby Urbandreamer » February 7th, 2024, 8:23 am

csearle wrote:
Urbandreamer wrote:While technically impossible to say, the double sockets that I have linked to are VERY different electrically.
Whilst not wanting to be combative, they are not really very different electrically. They are almost the same. They just have two Earths instead of one. If you leave linked the two Earth terminals they have the same function as conventional sockets as explained here.

I may be wrong but I think only plugs with special T shaped Earth pins will fit, thus continuing the two seperate Earths through into the equipment. Happy to be corrected on this though. C.


OK, it's not the socket that is electrically different, but how it's intended to be used.

There are entire books upon "earthing", because the word is used to mean many different things. Replacing the word with "bonding" only clarifies if you add extra terms, which could be done with the word earthing.

On the machines built where I worked the metal work was bonded using 10mm earth wires. This was not "protective" earthing the way that a domestic socket is earthed, but as a path for high frequency, low current, noise.
The main reason for the dimensions was not the current capacity (about 70A) but the circumference. Most of the current at these frequencies is carried in/on the surface.

Two wires have double the circumference and double the cross section. Also two wires must break to cause a safety fault. Hence the two terminals on one of the sockets that I linked.

Noise can also be carried where it isn't wanted by the earth wire. Hence the concept of a clean earth. This is a separate earth path.
The final link that I provided was to a clean earth double socket, without T shaped pin.

Re your own link, the "electrical" difference in that socket consists of a T shaped pin and markings. It's the electrical use that is different.

As I'm sure that you know, this sort of arrangement is only used if absolutely necessary to equipment function.

genou
Lemon Quarter
Posts: 1058
Joined: November 4th, 2016, 1:12 pm
Has thanked: 175 times
Been thanked: 364 times

Re: Double sockets - switches on the outside

#645430

Postby genou » February 7th, 2024, 7:11 pm

Urbandreamer wrote:The main reason for the dimensions was not the current capacity (about 70A) but the circumference. Most of the current at these frequencies is carried in/on the surface.


Wait, wait, what? I thought all current was carried in the fields around the wire. Enlighten me , please.

Urbandreamer
Lemon Quarter
Posts: 3039
Joined: December 7th, 2016, 9:09 pm
Has thanked: 340 times
Been thanked: 1000 times

Re: Double sockets - switches on the outside

#645435

Postby Urbandreamer » February 7th, 2024, 7:48 pm

genou wrote:
Urbandreamer wrote:The main reason for the dimensions was not the current capacity (about 70A) but the circumference. Most of the current at these frequencies is carried in/on the surface.


Wait, wait, what? I thought all current was carried in the fields around the wire. Enlighten me , please.


At DC frequencies, current flows through the bulk of the conductor. As the frequency increases conductivity tends towards the surface.
https://www.britannica.com/science/skin-effect

This phenomenon restricts the current to a small part of the total cross-sectional area and so has the effect of increasing the resistance of the conductor.


50Hz is quite a low frequency. Motor control these days is usually in the KHz range.

Since you are obviously interested, here is some advise to reduce pitting in bearings etc caused by induced sparking.
https://www.est-aegis.com/wp-content/up ... _Paper.pdf

9873210
Lemon Slice
Posts: 950
Joined: December 9th, 2016, 6:44 am
Has thanked: 223 times
Been thanked: 288 times

Re: Double sockets - switches on the outside

#645440

Postby 9873210 » February 7th, 2024, 8:01 pm

genou wrote:
Urbandreamer wrote:The main reason for the dimensions was not the current capacity (about 70A) but the circumference. Most of the current at these frequencies is carried in/on the surface.


Wait, wait, what? I thought all current was carried in the fields around the wire. Enlighten me , please.


It's energy that is carried in the fields around the wire. Energy flux is the Poynting vector.

In a vacuum the current is entirely inside the wire. Current requires charge carriers such as electrons and there are none in a vacuum. In practice there are few relevant charge carriers in any surrounding air or insulators, almost all the current will be in the wire. The restriction of the current to the surface of the wire is the skin effect.

(References to Wiki because they will almost certainly be more extensive and comprehensible than I could be in a reasonable time.)

genou
Lemon Quarter
Posts: 1058
Joined: November 4th, 2016, 1:12 pm
Has thanked: 175 times
Been thanked: 364 times

Re: Double sockets - switches on the outside

#645457

Postby genou » February 7th, 2024, 9:10 pm

9873210 wrote:
genou wrote:
Wait, wait, what? I thought all current was carried in the fields around the wire. Enlighten me , please.


It's energy that is carried in the fields around the wire.


That's the one. My bad.

Urbandreamer wrote: current flows through the bulk of the conductor.


This is where my brain hurts. I was brought up on the "water in a pipe" analogy, so "current flowing" takes me back to that. I later learned of its limitations. But other than electron drift, I have no mental picture of what is happening in the conductor.

I suspect I will never get to grips with this stuff without an OU effort, which I fear will not happen.

But thanks both. I do claim some points ( or make apologies ) for size of thread drift.

servodude
Lemon Half
Posts: 8177
Joined: November 8th, 2016, 5:56 am
Has thanked: 4378 times
Been thanked: 3524 times

Re: Double sockets - switches on the outside

#645461

Postby servodude » February 7th, 2024, 9:35 pm

genou wrote:This is where my brain hurts. I was brought up on the "water in a pipe" analogy, so "current flowing" takes me back to that. I later learned of its limitations. But other than electron drift, I have no mental picture of what is happening in the conductor.


Perhaps you can imagine ripples on the top of the water - that's a physical surface effect, a frequency of transmission that is superimposed on the main

When you look at an electrical circuit or schematic you can see what it will do at DC (or in a perfect physical representation).

Once you get to the shortcomings and compromises of "real life" you start to experience all sorts of "unexpected" things as frequency gets considered
Examples I see often would be cables removing top end ( working as low pass filters) because of capacitive coupling with the shield, and CM Chokes or beads being compromised on a circuit because of a ground plane beneath them
- and that fact that just about everything works as a RF transmitter or receiver (depending on where you are looking at it from :( )

Maroochydore
Lemon Slice
Posts: 472
Joined: May 11th, 2017, 8:33 pm
Has thanked: 81 times
Been thanked: 203 times

Re: Double sockets - switches on the outside

#645612

Postby Maroochydore » February 8th, 2024, 2:58 pm

pochisoldi wrote:Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?

Simple answer in my case, I have double sockets with USB charging sockets built in at the centre. Thus there is no room for switches on the inside. https://www.amazon.co.uk/BG-ELECTRICAL- ... r=8-5&th=1

That said, I have seen same set up with switches on the inside with USB charging sockets below the switches,
https://www.amazon.co.uk/MK-ELECTRIC-MB ... =8-16&th=1.

So I'm guessing the answer is purely aesthetics.

Lanark
Lemon Quarter
Posts: 1294
Joined: March 27th, 2017, 11:41 am
Has thanked: 583 times
Been thanked: 558 times

Re: Double sockets - switches on the outside

#645638

Postby Lanark » February 8th, 2024, 4:05 pm

pochisoldi wrote:Has anybody got any real life experiences with reasons why "switches on the outside" were fitted or should have been fitted?

They are also known as Hospital sockets and are used in any location where it is important you don't accidentally turn the wrong thing on or off, like turning the life support off instead of the bedside lamp.
I'm pretty sure the science labs at my old school had them.

I guess they are also considered uglier than the normal arrangement.

You could have a switch to the right of each socket, but then people might still think the switch in the middle was for the right hand socket.

pochisoldi
Lemon Slice
Posts: 933
Joined: November 4th, 2016, 11:33 am
Has thanked: 31 times
Been thanked: 456 times

Re: Double sockets - switches on the outside

#645961

Postby pochisoldi » February 9th, 2024, 5:29 pm

Thanks for everyone's replies.
The subtle "clean earth"/"high integrity earth" aspect wasn't obvious until you looked at the back of the sockets, and took me down a google worm hole.

As I suspected it seems to come down to "don't turn off the wrong socket" - something common to hospitals and data centres, with the latter requiring additional bonding due to higher overall earth leakage currents. (all those suppression capacitors connected to earth), so it would make sense to add the ability to split the protective earth function (contact with exposed metalwork that becomes live) and the functional earth connection which is used by the transient and noise filters fitted on the inputs of virtually every computing and networking device.

PochiSoldi

9873210
Lemon Slice
Posts: 950
Joined: December 9th, 2016, 6:44 am
Has thanked: 223 times
Been thanked: 288 times

Re: Double sockets - switches on the outside

#645974

Postby 9873210 » February 9th, 2024, 6:07 pm

genou wrote:I suspect I will never get to grips with this stuff without an OU effort, which I fear will not happen.


You never get to grips with everything. The more you know the more you know you don't know. On to a PhD, post doc, ... . At some point string theory will show up and strangle you.

genou
Lemon Quarter
Posts: 1058
Joined: November 4th, 2016, 1:12 pm
Has thanked: 175 times
Been thanked: 364 times

Re: Double sockets - switches on the outside

#645999

Postby genou » February 9th, 2024, 7:59 pm

9873210 wrote:
genou wrote:I suspect I will never get to grips with this stuff without an OU effort, which I fear will not happen.


You never get to grips with everything. The more you know the more you know you don't know. On to a PhD, post doc, ... . At some point string theory will show up and strangle you.


Indeed not. My father worked for PO Telecoms/ BT, and I am quite confident with domestic issues just by seeing/doing, but my theoretical understanding is appalling. But as Mr Clarke said Any sufficiently advanced technology is indistinguishable from magic.


Return to “Building and DIY”

Who is online

Users browsing this forum: No registered users and 2 guests