I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

Nick wrote:

Is it the Watts or the VA that will appear on my Electricity Bill.

For a domestic supply, it's the watts.

In article ,
Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

I'd not trust that sort of device to be anywhere near accurate at a very
low reading. You need to measure the current being drawn with a decent DVM.

Does the device have a written spec giving the accuracy?

--
*Great groups from little icons grow *

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

On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

These no load readings are technically unlikely and therefore incorrect.
The indication is that it is a pure inductor or capacitor.
The first doesn't exist and the second is unlikely.

Your meter is not up to the task.
However the power consumption must be very small indeed.

En el artículo , Nick
escribió:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-ge...ocket-3-1a-2g-
usb-charger-white/8529p.

I got the same one. It worked for a while but then my iPhone started
acting all weird when plugged into it, as if a phantom finger was
pressing random points on the screen. It was fine with the Apple
charger.

Took it back and got a refund.

--
(\_/)
(='.'=) systemd: the Linux version of Windows 10
(")_(")

On 24/01/2017 17:08, harry wrote:
On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

These no load readings are technically unlikely and therefore incorrect.
The indication is that it is a pure inductor or capacitor.
The first doesn't exist and the second is unlikely.

Your meter is not up to the task.
However the power consumption must be very small indeed.

The meter cannot be that bad.

On load have at most a 3A load at 5V (we have no idea what was plugged
in or it's charging rate), that's not far off the 12W showing on the meter.

When not on load the meter is showing the expected sweet FA apart from a
bit of capacitance.

--
Adam

Having said all of that, I'd suspect between 50 and 100 Milliamps off load
at least. My main concern about these devices are.
What fuse protection is there?None probably.
also such small transformers even if switch mode will be struggling to put
out the max current for 2 USB devices at the same time and..
3 Assuming switch mode, the interference will be terrible as hardly any
room for nice suppression of waveforms generated.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"harry" wrote in message
...
On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

These no load readings are technically unlikely and therefore incorrect.
The indication is that it is a pure inductor or capacitor.
The first doesn't exist and the second is unlikely.

Your meter is not up to the task.
However the power consumption must be very small indeed.

Yep that is the dirty nasty rfi generating crap in these devices alright.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Mike Tomlinson" wrote in message
...
En el artículo , Nick
escribió:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-ge...ocket-3-1a-2g-
usb-charger-white/8529p.

I got the same one. It worked for a while but then my iPhone started
acting all weird when plugged into it, as if a phantom finger was
pressing random points on the screen. It was fine with the Apple
charger.

Took it back and got a refund.

--
(\_/)
(='.'=) systemd: the Linux version of Windows 10
(")_(")

"Dave Plowman (News)" wrote:
In article ,
Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.


The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

I'd not trust that sort of device to be anywhere near accurate at a very
low reading. You need to measure the current being drawn with a decent DVM.

I agree about low readings being inaccurate. However reading the
current won't help much as you'll just get the VA not the watts and,
as someone else said, you're paying for the watts.

--
Chris Green
·

On 24/01/2017 19:51, Chris Green wrote:
"Dave Plowman (News)" wrote:
In article ,
Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.


The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

I'd not trust that sort of device to be anywhere near accurate at a very
low reading. You need to measure the current being drawn with a decent DVM.

I agree about low readings being inaccurate. However reading the
current won't help much as you'll just get the VA not the watts and,
as someone else said, you're paying for the watts.


OK I put a Maplin N56FU multimeter on it in series.

I'm reading 0.40 milliamps when off.

I'm getting 127 millamps on the N56FU when on.

When on the plug power socket reading about 10% less amps and 14 watts.

That looks to me like it really is not taking much power when off.

On 24/01/2017 19:14, Brian Gaff wrote:
Having said all of that, I'd suspect between 50 and 100 Milliamps off load
at least. My main concern about these devices are.

Seems to be 0.4 Milliamps when off.

What fuse protection is there?None probably.

What fuse protection would a normal usb plug in transformer have. Why
should I worry?

also such small transformers even if switch mode will be struggling to put
out the max current for 2 USB devices at the same time.

I don't understand this comment. AIUI It is one transformer rated at 3.1
Amps. A samsung tab and a smart phone do appear to put it at full load
(15 watts I assume 5v*3a)

and..
3 Assuming switch mode, the interference will be terrible as hardly any
room for nice suppression of waveforms generated.

Should I care about radio interference?

Brian

On 24/01/2017 17:59, Mike Tomlinson wrote:
En el artículo , Nick
escribió:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-ge...ocket-3-1a-2g-
usb-charger-white/8529p.

I got the same one. It worked for a while but then my iPhone started
acting all weird when plugged into it, as if a phantom finger was
pressing random points on the screen. It was fine with the Apple
charger.


I've had one for a month or so. I just bought a couple more as I liked
it so much.

Hopefully you just had bad luck.

On Tue, 24 Jan 2017 09:08:40 -0800 (PST), harry
wrote:

On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

These no load readings are technically unlikely and therefore incorrect.
The indication is that it is a pure inductor or capacitor.
The first doesn't exist and the second is unlikely.

Your meter is not up to the task.
However the power consumption must be very small indeed.

I thought the MK ones used no current at all when not in use.though I
cannot find authority for this.

On 24/01/2017 16:02, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.


The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

Not with such small amounts of power. Best thing you can do is go out
and buy another 99 sockets, wire all 100 up to the same supply, make
your measurement, and divide by 100.

Bill

On 24/01/2017 20:59, Nick wrote:
On 24/01/2017 19:51, Chris Green wrote:
"Dave Plowman (News)" wrote:
In article ,
Nick wrote:
I bought this double plug wall socket with two additional integrated
USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.



The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

I'd not trust that sort of device to be anywhere near accurate at a very
low reading. You need to measure the current being drawn with a
decent DVM.

I agree about low readings being inaccurate. However reading the
current won't help much as you'll just get the VA not the watts and,
as someone else said, you're paying for the watts.


OK I put a Maplin N56FU multimeter on it in series.

I'm reading 0.40 milliamps when off.

I'm getting 127 millamps on the N56FU when on.

When on the plug power socket reading about 10% less amps and 14 watts.

That looks to me like it really is not taking much power when off.

Which is what you would expect for a switched mode PSU.


--
Cheers,

John.

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

On 24/01/2017 17:08, harry wrote:
On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

These no load readings are technically unlikely and therefore incorrect.
The indication is that it is a pure inductor or capacitor.
The first doesn't exist and the second is unlikely.

The second is not only likely, its exactly what you would expect the
see. Most switching supplies of that type will rectify the mains and
charge a capacitor. That will in turn feed the rest of the supply. The
current draw will tend to only be near the peaks of the voltage
waveform, as the cap is only "topped up" by the mains peaks when under
load. The result being nearly zero power factor when under no load.

Your meter is not up to the task.

This is likely true. You would probably need to measure the voltage drop
across a calibrated shunt resistor on a scope to capture the current
pulse waveform. You could then integrate the capture to calculate the
actual power drawn.

However the power consumption must be very small indeed.

Indeed

--
Cheers,

John.

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

On 24/01/2017 16:02, Nick wrote:

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

This may help:

wiki.diyfaq.org.uk/index.php/Power_factor


--
Cheers,

John.

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

On Tuesday, 24 January 2017 21:04:07 UTC, Nick wrote:
On 24/01/2017 19:14, Brian Gaff wrote:

Having said all of that, I'd suspect between 50 and 100 Milliamps off load
at least. My main concern about these devices are.

Seems to be 0.4 Milliamps when off.

as good as zero, if that's ac current. Most meters only measure dc current.

What fuse protection is there?None probably.

What fuse protection would a normal usb plug in transformer have.

Someing in the vague region of 1A

Why
should I worry?

fire & shock risk

also such small transformers even if switch mode will be struggling to put
out the max current for 2 USB devices at the same time.

I don't understand this comment. AIUI It is one transformer rated at 3.1
Amps. A samsung tab and a smart phone do appear to put it at full load
(15 watts I assume 5v*3a)

completely trivial

and..
3 Assuming switch mode, the interference will be terrible as hardly any
room for nice suppression of waveforms generated.

Should I care about radio interference?

if you care about radio reception.

The real reason not to buy these things is that 5v USB is most likely a short term standard that will be replaced by negotiable voltage. Ie their usability will fizzle out. Plus they're overpriced and often unsafe.


NT

On Tuesday, 24 January 2017 17:59:42 UTC, ARW wrote:
On 24/01/2017 17:08, harry wrote:
On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

These no load readings are technically unlikely and therefore incorrect.
The indication is that it is a pure inductor or capacitor.
The first doesn't exist and the second is unlikely.

Your meter is not up to the task.
However the power consumption must be very small indeed.

The meter cannot be that bad.

On load have at most a 3A load at 5V (we have no idea what was plugged
in or it's charging rate), that's not far off the 12W showing on the meter.

When not on load the meter is showing the expected sweet FA apart from a
bit of capacitance.

--
Adam

It must be consuming something.
Even if very tiny.

On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

It's possible that these devices are only switched "on" when the plug is inserted.
That would account for the ultra low readings.
It would also make them a lot safer.
Without a switch I would say they are a significant extra fire hazard.

You need to check the load with a plug inserted (but not connected to anything) to check this out.
Or take one to bits

On Wednesday, 25 January 2017 08:30:00 UTC, harry wrote:
On Tuesday, 24 January 2017 16:02:21 UTC, Nick wrote:
I bought this double plug wall socket with two additional integrated USB
sockets.

http://www.screwfix.com/p/british-general-13a-2g-sp-switched-socket-3-1a-2g-usb-charger-white/8529p.

The on/off switches do not control the USB sockets. So I started
wondering about the USB transformer eating current when no USB devices
are connected.

So I wired it up to a standard plug and tested it with a standard plug
power meter. Probably not the most accurate test.

With nothing plugged in it reads 0 Watts but 2 VA.

With a couple of things plugged in it reads 12 Watts and 21 VA.

Not being an electrician I'm not sure about this VA stuff. Is it the
Watts or the VA that will appear on my Electricity Bill.

It's possible that these devices are only switched "on" when the plug is inserted.
That would account for the ultra low readings.
It would also make them a lot safer.
Without a switch I would say they are a significant extra fire hazard.

You need to check the load with a plug inserted (but not connected to anything) to check this out.
Or take one to bits

Further to above.
If they do have a switch, it means if you don't remove the lead, power will be consumed all the time and you have the extra fire risk.

I see a lot of people leaver chargers etc plugged in when not in use so I expect they'll leave this lead plugged in too.