Unswitched wall sockets

[GAClarke]

I am having an additional mains spur installed in my house. It will only be feeding a single double wall socket and will be connected to a 32A RCD within a mains consumer unit.

I've been told that I can not use an unswitched wall socket as "each circuit must have a switch".

Is this correct? All items that will be connected to these sockets have internal fuses (as do the mains leads), so is it dangerous using an unswitched socket?

Thanks.

 

[ericmark]

Plug and unswitched socket-outlet is suitable for on-load isolation, i.e. disconnection whilst carrying load current. (537.1.1) can be used for Isolation or Functional Switching but not Emergency Switching and the switched version is the same.

So no need to have switches on the socket. In fact there is no electrical advantage.

Having said that I would normally fit switched versions where items like TV are switched off at night it means you don't have to bend down so far to get the plug when switching on again.

 

[AndyPRK]

Why don't you want switches on the sockets?

Not taking about the fcu are you?

 

[JohnD]

is there a reason why you think you will benefit from having unswitched sockets?

 

[ericmark]

As a P.S. the BS7671:2008 is very easy to misread for example. 537.1.4 A main linked switch or linked circuit-breaker shall be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation. A main switch intended for operation by ordinary persons, e.g. of a household or similar installation. shall interrupt both live conductors of a single-phase supply.

This refers to the main isolator in the CU and as one reads on there are other regulations which can be confusing which includes the switching of the neutral. I have found switched sockets with both just line switched and line and neutral switched and where the house has a TT earth system then it should be double pole but without putting a meter on the socket it is hard to tell if single or double pole so with an ordinary person doing the work likely less risk using a unswitched socket as users will unplug when not in use and for a ordinary person to work out if house has TT or TN supply or to test socket to see if single or double pole switched would be hard.

We have definitions which would likely confuse like a circuit is defined by all protected by one protective device, and both line and neutral are classed as live, and 230vac is classed as low voltage and this means people flitting through regulation pages can make mistakes including me.

 

[AndyPRK]

That's certainly a new regulation to me!

TT Systems should have DP switched sockets.

 

[GAClarke]

is there a reason why you think you will benefit from having unswitched sockets?

This is a dedicated spur for a high end (read: expensive!) hifi system.

I now expect you all to jump on my saying it won't make a difference

The spur is being installed by an electrician. The unswitched socket is already in place. It was installed at the same time that I replaced my existing mains block for a better quality one (also unswitched, with no power on LED and better quality mains rails).

Apparently removal of the switch reduces the impedance (so I am told).

Regardless of whether that is true or not, there was a noticeable improvement in the sound quality.

 

[phatboy]

Apparently removal of the switch reduces the impedance (so I am told).

Regardless of whether that is true or not, there was a noticeable improvement in the sound quality.

What rubbish! And the improved sound quality was noticed because you wanted to notice it. If someone moved it to a switched socket and standard extension cable without you knowing, you wouldn't notice.

Think of all the upstream switches and other equipment that you have no control of.....

Anyway, just my opinion!

 

[GAClarke]

Apparently removal of the switch reduces the impedance (so I am told).

Regardless of whether that is true or not, there was a noticeable improvement in the sound quality.

What rubbish! And the improved sound quality was noticed because you wanted to notice it. If someone moved it to a switched socket and standard extension cable without you knowing, you wouldn't notice.

Think of all the upstream switches and other equipment that you have no control of.....

Anyway, just my opinion!

<sigh>

Well, I respect the fact that you are entitled to your opinion but have you actually tried this? Are you talking from experience or just what you "think" would be the case?

 

[rjm2k]

Every socket from different or even the same manufacturer will have a different impedance to the next. You could always measure it.

Anyway "each circuit must have a switch".

a socket it not a circuit, it's part of a circuit and you have a switch (read way of isolating) at the CU.

 

[Taylortwocities]

Why not go the whole hog.

Go buy one of Russ Andrews "Super Sockets"
A snip at £18 each (it looks like an MK Logic socket to me).

WHile you are at it, you need to buy a quantity of his "reference" 13A plugs. A snip at £7.90 each

 

[ericmark]

Now that changes everything of course you want a switch. With a filtered socket you have a module which will need changing every now and again so you don't want it powered at all times and also you want to switch if off when testing so testing will not damage the module so for a HiFi feed yes it will always be a switched socket simply so the filter module can be switched off.

As to loop impedance yes the filtered socket will increase the reading but one would hope your not right on the edge and with B32 MCB as long as under 1.44 ohms there is no problem.

If a switch in a socket produces noise on a HiFi then it's faulty it's not because it's switched it's just there is a fault on the socket. Using a loop impedance tester will often highlight faults on sockets but it could also be simply the plug used has dirt on pins which is cleaned off by new tighter grip of any new socket so unless you also swapped back to old socket to retest you would not know.

Although mains born interference can upset a HiFi I personally would be looking at HiFi. I remember as an apprentice fitting a car radio and trying to stop interference chokes, capacitors galore with earth straps the lot and I just could not stop the interference. An old guy came up with a radio in his hand and said try this one. I did not a crackle. It was not the car at fault it was the radio. The same with mains HiFi and price does not seem to matter some just don't have the rejection they should have built in.

 

[ericmark]

Why not go the whole hog.

Go buy one of Russ Andrews "Super Sockets"
A snip at £18 each (it looks like an MK Logic socket to me).

WHile you are at it, you need to buy a quantity of his "reference" 13A plugs. A snip at £7.90 each

That's rather cheap for a filtered socket seems it's just an ordinary socket with switch cleaner sprayed on it. Now this looks more like it snip at £79 pounds and not a word about any filter fitted. But this one at nearly £60 is a least a proper filter socket as yes it is switched.

 

[FDJ]

Apparently removal of the switch reduces the impedance (so I am told).

Regardless of whether that is true or not, there was a noticeable improvement in the sound quality.

What rubbish! And the improved sound quality was noticed because you wanted to notice it. If someone moved it to a switched socket and standard extension cable without you knowing, you wouldn't notice.

Think of all the upstream switches and other equipment that you have no control of.....

Anyway, just my opinion!

<sigh>

Well, I respect the fact that you are entitled to your opinion but have you actually tried this? Are you talking from experience or just what you "think" would be the case?

You are asking this on a "technical" forum.
Most of the guys here have a good Electrical Theory knowledge.
Do you?
You must realise that the Hi-Fi industry is full of con men and purveyors of "snake oil".

The TINY impedances present in the electrical supply network will not affect any well designed audio gear.
Trust me... They won't.

Frank

 

[ekmdgrf]

http://en.wikipedia.org/wiki/Placebo

You should really do a blind trial on this.

On the subject of the plug, you'd be better off running the whole thing on a lead acid battery. Nice stable 12V DC supply, none of that noise mains rubbish and you can also do away with the transformer in the amp. Try to get a battery with gold terminals of course.

I know it's a bit of a pain in the arse to charge the battery but wait until you hear the difference.