Extension block switches neutral not live

[Chris Glen-Smith]

Hi

I have a master slave extension block that automatically switches on/off
6 slave sockets when whatever is plugged into a master socket is
switched on/off, in this case my PC. It is labelled TCM, I bought it
almost a year ago.

The other day it stopped working and me being me I took it apart to see
what was wrong (I was trained as an electronics engineer).

I found the problem (a blown thermal fuse) but I was gob smacked to
discover that it switches the neutral and not the live, i.e. the slave
sockets are turned off by isolating the neutral and the live is still
live. *

Is that legal? (I'm in the UK).

* That explained an odd behaviour I saw a few months ago when a PC
speaker system I bought remained powered when plugged into the slave
sockets even when they were off, it guess it earthed some part of it's
PSU for some reason.

Regards
Chris

 

[Rusty]

Hi

I have a master slave extension block that automatically switches on/off
6 slave sockets when whatever is plugged into a master socket is
switched on/off, in this case my PC. It is labelled TCM, I bought it
almost a year ago.

The other day it stopped working and me being me I took it apart to see
what was wrong (I was trained as an electronics engineer).

I found the problem (a blown thermal fuse) but I was gob smacked to
discover that it switches the neutral and not the live, i.e. the slave
sockets are turned off by isolating the neutral and the live is still
live. *

Is that legal? (I'm in the UK).

* That explained an odd behaviour I saw a few months ago when a PC
speaker system I bought remained powered when plugged into the slave
sockets even when they were off, it guess it earthed some part of it's
PSU for some reason.

Regards
Chris

I wouldn't think it is legal in any part of the world. It certainly
isn't in North America. The potential for shock and death is very
high, especially if a child or infirm adult touched something hot
while grounded. Throw it away and check any replacement you buy.

 

[Roy Q.T.]

Only if it is a Low Voltage Control Master/Slave System

Where the AC [household] Outlet is shut on & off by the Masters Command
to Trigger the Slaves.

No Killer AC actually runs through it, Only Conventional Receptacle
Dangers Apply, check your Polarities.

 

[Roy Q.T.]

Is it an X-10 system ?

That's very cool, how much did it cost you?

 

[Roy Q.T.]

If it keeps giving you trouble, do llike Rusty says, throw it away
immediatley ! }:-o teeheehee

Toss It All in Rustys' Garbage Can}-)

or givem here, i'll dispose ovem for ya }

 

[Dimitrios Tzortzakakis]

Get a power strip with a switch on,like mine.When you switch off your
computer, switch off that too, so that everything connected on it will be
off.They are cheap, here you can get one for less than 5 euro.

 

[Paul E. Bennett]

Hi

I have a master slave extension block that automatically switches on/off
6 slave sockets when whatever is plugged into a master socket is
switched on/off, in this case my PC. It is labelled TCM, I bought it
almost a year ago.

The other day it stopped working and me being me I took it apart to see
what was wrong (I was trained as an electronics engineer).

I found the problem (a blown thermal fuse) but I was gob smacked to
discover that it switches the neutral and not the live, i.e. the slave
sockets are turned off by isolating the neutral and the live is still
live. *

Is that legal? (I'm in the UK).

* That explained an odd behaviour I saw a few months ago when a PC
speaker system I bought remained powered when plugged into the slave
sockets even when they were off, it guess it earthed some part of it's
PSU for some reason.

Is this product CE marked?

I think that you will find that the device is not legal and you should
speak to the Trading Standards Office in your area.

--
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Paul E. Bennett ....................<email://peb@a...>
Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972 .........NOW AVAILABLE:- HIDECS COURSE......
Tel: +44 (0)1235-811095 .... see http://www.feabhas.com for details.
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************

 

[Chris Glen-Smith]

Hi

I have a master slave extension block that automatically switches on/off
6 slave sockets when whatever is plugged into a master socket is
switched on/off, in this case my PC. It is labelled TCM, I bought it
almost a year ago.

The other day it stopped working and me being me I took it apart to see
what was wrong (I was trained as an electronics engineer).

I found the problem (a blown thermal fuse) but I was gob smacked to
discover that it switches the neutral and not the live, i.e. the slave
sockets are turned off by isolating the neutral and the live is still
live. *

Is that legal? (I'm in the UK).

* That explained an odd behaviour I saw a few months ago when a PC
speaker system I bought remained powered when plugged into the slave
sockets even when they were off, it guess it earthed some part of it's
PSU for some reason.

Regards
Chris

Hi again

I don't know what an "X-10 system" is, sounds flash, this is just bit of
flex with a mains plug one end and a box of sockets etc the other, it
cost 12 UK pounds of so I think, from a gadget shot in the mall.

It worked well, it was convenient being able to select shutdown and walk
away know everything would switch off after the PC shutdown. I can
easily repair it but I'm not sure I want to use it now.

Killer AC definately runs through it! Except for the sockets it's all on
a PCB. The feed to the Master 230VAC live does a couple of turns round a
toroid core to sense the load which drives some electronics which drives
a relay. The relay contacts are in series with the slave neutral, the
slave live is wired directly to incoming live via a PCD mounted thermal
fuse (temperature sensing solid state thing I think, not a "fuse" fuse.

The master socket is always on (i.e. it's unswitched) while it is
plugged into the wall socket, perhaps that makes it OK to leave the
slave socket lives live even when it switches them off.

Mostly I'm just amazed it was certified (or whatever the approval is)
for sale.

Cheers
Chris

 

[Chris Glen-Smith]

Hi Paul

Yes it has a CE marking, I just checked.

Chris Glen-Smith wrote:




Is this product CE marked?

I think that you will find that the device is not legal and you should
speak to the Trading Standards Office in your area.

 

[Bill Kaszeta / Photovoltaic Resources]

Only if it is a Low Voltage Control Master/Slave System

Where the AC [household] Outlet is shut on & off by the Masters Command
to Trigger the Slaves.

No Killer AC actually runs through it, Only Conventional Receptacle
Dangers Apply, check your Polarities.

It is likely that your wireless device has an input circuit with a dc voltage
across the inputs when the input is open (that is how the open contacts
are sensed). One side is likely common with one terminal of the
battery.

You should try putting a power FET device across the input (source
and drain) and using a capacitor from source to gate to hold the
FET on for a period after your relay opens. A resistor across the
capacitor sets the discharge period. I would start with 470 MF and
1meg resistor for 4-5 minutes delay (depends on gate voltage on
turn-off, device specific).

If the battery negative is common to one of the input terminals,
use a N-channel FET (I did something similar with an IRF520,
way over kill on current, but you are not likely to damage it).
If the wireless device voltage is only 3 volts, you will need a
FET designed for logic level gate voltages.

Connect as follows:
Source of FET to - input terminal
Drain of FET to the other input terminal
Capacitor negative (use 16V cap) to Source
Capacitor positive to Gate
1 meg resistor across capacitor
100K resistor to battery +, other side of 100K to one of your relay contacts
Other relay contact to Gate.

Use a grounded soldering iron as the FET gate can be
damaged by static electricity.

If the battery positive is common to one of the input terminals,
use a P-channel FET and reverse all polarities listed above.

When the relay contacts are closed, the 100K resistor uses the
battery to charge the capacitor. Voltage on the capacitor keeps
the FET ON.

When the relay contacts open (on power fail) the capacitor holds
a charge while the 1 meg resistor discharges the capacitor. At
some low voltage on the Gate, the wireless sensor will detect an
open circuit and send the alarm. Experiment with resistance and
capacitance to get an acceptable time delay.

If you shop the parts, likely cost per circuit is
USD $2.00-4 .00.
Bill Kaszeta
Photovoltaic Resources Int'l
Tempe Arizona USA
[email protected]

 

[Bill Kaszeta / Photovoltaic Resources]

OOPS! Sorry about previous post, I replied to the wrong question.

Only if it is a Low Voltage Control Master/Slave System

Where the AC [household] Outlet is shut on & off by the Masters Command
to Trigger the Slaves.

No Killer AC actually runs through it, Only Conventional Receptacle
Dangers Apply, check your Polarities.

Bill Kaszeta
Photovoltaic Resources Int'l
Tempe Arizona USA
[email protected]

 

[Roy Q.T.]

X 10 is registered mark and has a totally wireless control for
household ac receptacles.

Your's is just a Hardwired Extension with receptacles attached to it,
Not much remotes controll as we assumed, furher more, you have 220vac
and you will always have a Live Wire present on your Receptacles Line
In., the system you have employed is obviously for use on a 110 system
where there is 1Hot and 1Neutral] { In your 220vac household system
there's 1Hot and 1Return also Hot for control purposes there is a little
more considertion that one wire isolation for the elctronics to perform.

Tidy it up and send to one of your US Buddies we would have no problem
with it.

Roy