[EE] Is this safe?

[David C Brown]

https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=AC+220V+Timer+Delay+Switch+Module+Input%2FOutput+Turn+Off+Board+Time+

I need a timer to control outdoor lamps on my "estate". Using a module
like the one above would have the advantage that the operating switches -
all outdoor - would be at a low voltage, meaning that the wiring is less
onerous.

But my concern is that the isolation between the 240vac and the the "cold"
trigger terminals may not be adequate. My worry is that a failure could
put the 240v onto the trigger wires.

Looking at the pictures there is obviously no full isolation between 240v
and low voltage , nor can I see a properly rated capacitor..

Comments welcomed

__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

[Manu Abraham]

Rather than "no full isolation"; AFAICS, no isolation for the
capacitor coupled power supply

Post by David C Brown
https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=AC+220V+Timer+Delay+Switch+Module+Input%2FOutput+Turn+Off+Board+Time+
I need a timer to control outdoor lamps on my "estate". Using a module
like the one above would have the advantage that the operating switches -
all outdoor - would be at a low voltage, meaning that the wiring is less
onerous.
But my concern is that the isolation between the 240vac and the the "cold"
trigger terminals may not be adequate. My worry is that a failure could
put the 240v onto the trigger wires.
Looking at the pictures there is obviously no full isolation between 240v
and low voltage , nor can I see a properly rated capacitor..
Comments welcomed
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*
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[Sean Breheny]

I looked at the underside of the board as shown on Amazon and made some
rough estimates of clearances on the board. It looks like the closest
pri-sec spacing is 2.4mm. My notes suggest that this should never be less
than 5mm unless conformal coat is used. So, no, I do not think this is
properly designed. It also uses a capacitive voltage dropping power supply
which could fail in ways that aren't entirely safe (current would still be
limited by the capacitor but without more info I can' say whether it would
be limited to a safe value)

Here's the image I annotated:
http://tinypic.com/r/ea39jp/9



Sean

​

Post by David C Brown
https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-
alias%3Daps&field-keywords=AC+220V+Timer+Delay+Switch+
Module+Input%2FOutput+Turn+Off+Board+Time+
I need a timer to control outdoor lamps on my "estate". Using a module
like the one above would have the advantage that the operating switches -
all outdoor - would be at a low voltage, meaning that the wiring is less
onerous.
But my concern is that the isolation between the 240vac and the the "cold"
trigger terminals may not be adequate. My worry is that a failure could
put the 240v onto the trigger wires.
Looking at the pictures there is obviously no full isolation between 240v
and low voltage , nor can I see a properly rated capacitor..
Comments welcomed
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*
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[Ruben Jönsson]

The relay: Primary to secondary creepage distances with a working voltage of below 300 V rms, pollution degree 2, material group IIIb for basic insulation is 3.2 mm for IEC/UL 60950-1 and 3.0 mm for IEC/UL 61010-1 (up to 2000m altitude).

You need reinforced or double insulation for accessible parts. The supplementary insulation&nbsp;may consist of&nbsp;a plastic enclosure (of adequate mechanical strength and UV-durability if for outdoors) or a protectively earthed metal enclosure. Note also that there are&nbsp;requirements for field wiring and connectors. The external switch needs double/reinforced insulation to accessible parts if it is directly connected to mains (which this seems to be).

Primary to secondary&nbsp;insulation could consist of an impedance, which the capacitor is between mains and secondary. Note that you need capacitors in series with both the line and the neutral mains connection. This puts additional requirements on the type of the capacitor. It should be certified and of certain type or class since it needs to be considered as&nbsp;infallible. If this isn't equivalent to double/reinforced insulation, you still need another means of protection for the&nbsp;external switch connected to secondary voltage. I have never done this and am not quite sure if you can provide double/reinforced insulation with capacitors in this way.

Strictly speaking, you only need functional insulation if the relay output is going to be connected to mains and the access to the external switch has double/reinforced insulation. Most standards still need the device to be safe in case of a single fault regarding overheating and fire.

/Ruben

Den Thu, 19 Jul 2018 16:01:13 -0400, Sean Breheny skrev:

I looked at the underside of the board as shown on Amazon and made some
rough estimates of clearances on the board. It looks like the closest
pri-sec spacing is 2.4mm. My notes suggest that this should never be less
than 5mm unless conformal coat is used. So, no, I do not think this is
properly designed. It also uses a capacitive voltage dropping power supply
which could fail in ways that aren't entirely safe (current would still be
limited by the capacitor but without more info I can' say whether it would
be limited to a safe value)

Here's the image I annotated:
http://tinypic.com/r/ea39jp/9



Sean

​

On Thu, Jul 19, 2018 at 3:08 PM, David C Brown wrote:

&gt; https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-
&gt; alias%3Daps&amp;field-keywords=AC+220V+Timer+Delay+Switch+
&gt; Module+Input%2FOutput+Turn+Off+Board+Time+
&gt;
&gt; I need a timer to control outdoor lamps on my "estate". Using a module
&gt; like the one above would have the advantage that the operating switches -
&gt; all outdoor - would be at a low voltage, meaning that the wiring is less
&gt; onerous.
&gt;
&gt; But my concern is that the isolation between the 240vac and the the "cold"
&gt; trigger terminals may not be adequate. My worry is that a failure could
&gt; put the 240v onto the trigger wires.
&gt;
&gt; Looking at the pictures there is obviously no full isolation between 240v
&gt; and low voltage , nor can I see a properly rated capacitor..
&gt;
&gt; Comments welcomed
&gt;
&gt; __________________________________________
&gt; David C Brown
&gt; 43 Bings Road
&gt; Whaley Bridge
&gt; High Peak Phone: [phone]
&gt; Derbyshire eMail: ***@gmail.com
&gt; SK23 7ND web: www.bings-knowle.co.uk/dcb
&gt;
&gt;
&gt;
&gt;
&gt; *Sent from my etch-a-sketch*
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&gt; http://mailman.mit.edu/mailman/listinfo/piclist
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&nbsp;

[Allen Mulvey]

I have a small board for a 555 timer. You could populate it,
power it from a wall wart, and put the relay inside an
appropriate electrical box. I used to have relays that
mounted on the cover of an electrical box with the contacts
inside and the coil wires outside but I haven't seen
anything like that in a very long time.

Send me a mailing address offline and I'll send you one to
play with.

Allen

-----Original Message-----
From: piclist-***@mit.edu
[mailto:piclist-***@mit.edu] On Behalf Of David C Brown
Sent: Thursday, July 19, 2018 3:08 PM
To: Microcontroller discussion list - Public.
Subject: [EE] Is this safe?

https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3
Daps&field-keywords=AC+220V+Timer+Delay+Switch+Module+Input%
2FOutput+Turn+Off+Board+Time+

I need a timer to control outdoor lamps on my "estate".
Using a module
like the one above would have the advantage that the
operating switches -
all outdoor - would be at a low voltage, meaning that the
wiring is less
onerous.

But my concern is that the isolation between the 240vac and
the the "cold"
trigger terminals may not be adequate. My worry is that a
failure could
put the 240v onto the trigger wires.

Looking at the pictures there is obviously no full isolation
between 240v
and low voltage , nor can I see a properly rated capacitor..

Comments welcomed

__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



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[David C Brown]

That is very kind of you, Allen. But I already have boards like that And
I prefer to avoid wall warts.. Thanks again

__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by Allen Mulvey
I have a small board for a 555 timer. You could populate it,
power it from a wall wart, and put the relay inside an
appropriate electrical box. I used to have relays that
mounted on the cover of an electrical box with the contacts
inside and the coil wires outside but I haven't seen
anything like that in a very long time.
Send me a mailing address offline and I'll send you one to
play with.
Allen
-----Original Message-----
Sent: Thursday, July 19, 2018 3:08 PM
To: Microcontroller discussion list - Public.
Subject: [EE] Is this safe?
https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3
Daps&field-keywords=AC+220V+Timer+Delay+Switch+Module+Input%
2FOutput+Turn+Off+Board+Time+
I need a timer to control outdoor lamps on my "estate".
Using a module
like the one above would have the advantage that the
operating switches -
all outdoor - would be at a low voltage, meaning that the
wiring is less
onerous.
But my concern is that the isolation between the 240vac and
the the "cold"
trigger terminals may not be adequate. My worry is that a
failure could
put the 240v onto the trigger wires.
Looking at the pictures there is obviously no full isolation
between 240v
and low voltage , nor can I see a properly rated capacitor..
Comments welcomed
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*
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[James Cameron]

I agree with Sean.

I'd use 240V wiring standards for taking the trigger input away from
the boundary of a product casing or back of a light switch plate.

It isn't clear from the description if the product can work reliably
with a remote trigger. Description also suggests it will power on
each time an unreliable grid comes up, "Power on and trigger to
connect", which may not be wanted.

p.s. the 240V standards here are called "low voltage" most of the
time, so I had to recalibrate my reading glasses. ;-)

Post by David C Brown
https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=AC+220V+Timer+Delay+Switch+Module+Input%2FOutput+Turn+Off+Board+Time+
I need a timer to control outdoor lamps on my "estate". Using a module
like the one above would have the advantage that the operating switches -
all outdoor - would be at a low voltage, meaning that the wiring is less
onerous.
But my concern is that the isolation between the 240vac and the the "cold"
trigger terminals may not be adequate. My worry is that a failure could
put the 240v onto the trigger wires.
Looking at the pictures there is obviously no full isolation between 240v
and low voltage , nor can I see a properly rated capacitor..
Comments welcomed
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*
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[s***@agilent.com]

Yep - no doubt. The whole board is effectively at mains potential. Even adjusting the trimpot could "tingly" at the least. External wiring to the "key" needs to be mains rated, as does the switch attached.

No sign of any compliance marks either (any wonder?)

Wouldn't be for me and mine...

Stephen

-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of James Cameron
Sent: Friday, 20 July 2018 6:35 AM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] Is this safe?

I agree with Sean.

I'd use 240V wiring standards for taking the trigger input away from the boundary of a product casing or back of a light switch plate.

It isn't clear from the description if the product can work reliably with a remote trigger. Description also suggests it will power on each time an unreliable grid comes up, "Power on and trigger to connect", which may not be wanted.

p.s. the 240V standards here are called "low voltage" most of the time, so I had to recalibrate my reading glasses. ;-)

Post by David C Brown
https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field
-keywords=AC+220V+Timer+Delay+Switch+Module+Input%2FOutput+Turn+Off+Bo
ard+Time+
I need a timer to control outdoor lamps on my "estate". Using a module
like the one above would have the advantage that the operating
switches - all outdoor - would be at a low voltage, meaning that the
wiring is less onerous.
But my concern is that the isolation between the 240vac and the the "cold"
trigger terminals may not be adequate. My worry is that a failure could
put the 240v onto the trigger wires.
Looking at the pictures there is obviously no full isolation between
240v and low voltage , nor can I see a properly rated capacitor..
Comments welcomed
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*
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--
James Cameron
http://quozl.netrek.org/
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[RussellMc]

Using the module to control a relay of your choice would give you control
of the isolation.

Note that many of the '5v-control to SPDT or DPDT mains contacts" relay
modules sold for use with eg Arduinos use relays which have impressive PCB
isolation distances between the coil contacts and two of the 3 terminals of
their SPDT switches BUT locate the centre contact adjacent to the coil
contacts.


Russell

[Allen Mulvey]

While looking for something else I came across this:
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0

Use the 555 module to switch this one as Russell suggests.

Allen

-----Original Message-----
From: piclist-***@mit.edu
[mailto:piclist-***@mit.edu] On Behalf Of RussellMc
Sent: Thursday, July 19, 2018 5:38 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Is this safe?

Using the module to control a relay of your choice would
give you control
of the isolation.

Note that many of the '5v-control to SPDT or DPDT mains
contacts" relay
modules sold for use with eg Arduinos use relays which have
impressive PCB
isolation distances between the coil contacts and two of the
3 terminals of
their SPDT switches BUT locate the centre contact adjacent
to the coil
contacts.


Russell
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[RussellMc]

That looks good as an example - BUT: any add on solution needs to be
checked to ensure that it fixes the isolation issue and does not have
issues of its own.

Russell

Post by Allen Mulvey
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0
Use the 555 module to switch this one as Russell suggests.
Allen

[David C Brown]

Thank you all for your advice. It is clear that this module is not safe
enough to use in the way I envisaged. I am now tending towards using
wireless remote control modules. Twenty feet of air, even humid air, is a
damn fine piece of isolation. :-)

__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by RussellMc
That looks good as an example - BUT: any add on solution needs to be
checked to ensure that it fixes the isolation issue and does not have
issues of its own.
Russell

Post by Allen Mulvey
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0
Use the 555 module to switch this one as Russell suggests.
Allen

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[Manu Abraham]

A quick suggestion: If you still want to use that module and still want
the isolation, connect an optocoupler to the control interface, which will
give an adequate isolation. Just that you will need to tinker with it.

Cheers,
Manu

Post by David C Brown
Thank you all for your advice. It is clear that this module is not safe
enough to use in the way I envisaged. I am now tending towards using
wireless remote control modules. Twenty feet of air, even humid air, is a
damn fine piece of isolation. :-)
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by RussellMc
That looks good as an example - BUT: any add on solution needs to be
checked to ensure that it fixes the isolation issue and does not have
issues of its own.
Russell

Post by Allen Mulvey
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0
Use the 555 module to switch this one as Russell suggests.
Allen

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[Ruben Jönsson]

If you are going this route, you need to make sure that the isolation provided by the optocoupler is adequate. It needs double/reinforced insulation and a&nbsp;withstand voltage of between 3000 and 4000 V AC rms (depending on standard it should comply with). Required creepage distance could be as high as 8mm which means that you need an optocoupler with "wide" pin configuration.

Many standards needs this type of component (components with high integrity characteristic - one&nbsp;fault could lead to unacceptable risk)&nbsp;to be routine tested (each individual example is tested for electrical withstand, not just type tested by the manufacturer).

You still need "safe" power on the insulated side of the opto coupler (the led side).

There are no&nbsp;shortcuts when it comes to insulation and safety.


/Ruben

Den Fri, 20 Jul 2018 16:34:13 +0530, Manu Abraham skrev:

A quick suggestion: If you still want to use that module and still want
the isolation, connect an optocoupler to the control interface, which will
give an adequate isolation. Just that you will need to tinker with it.

Cheers,
Manu


On Fri, Jul 20, 2018 at 3:49 PM, David C Brown wrote:
&gt; Thank you all for your advice. It is clear that this module is not safe
&gt; enough to use in the way I envisaged. I am now tending towards using
&gt; wireless remote control modules. Twenty feet of air, even humid air, is a
&gt; damn fine piece of isolation. :-)
&gt;
&gt; __________________________________________
&gt; David C Brown
&gt; 43 Bings Road
&gt; Whaley Bridge
&gt; High Peak Phone: [phone]
&gt; Derbyshire eMail: ***@gmail.com
&gt; SK23 7ND web: www.bings-knowle.co.uk/dcb
&gt;
&gt;
&gt;
&gt;
&gt; *Sent from my etch-a-sketch*
&gt;
&gt; On 20 July 2018 at 08:30, RussellMc wrote:
&gt;
&gt;&gt; That looks good as an example - BUT: any add on solution needs to be
&gt;&gt; checked to ensure that it fixes the isolation issue and does not have
&gt;&gt; issues of its own.
&gt;&gt;
&gt;&gt; Russell
&gt;&gt;
&gt;&gt;
&gt;&gt;
&gt;&gt; On 20 July 2018 at 11:22, Allen Mulvey wrote:
&gt;&gt;
&gt;&gt; &gt; While looking for something else I came across this:
&gt;&gt; &gt; Enclosed Pre-Wired Relay
&gt;&gt; &gt; https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
&gt;&gt; &gt; sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
&gt;&gt; &gt; 387&amp;hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&amp;_sacat=0&amp;_nkw
&gt;&gt; &gt; =enclosed+pre-wired+relay&amp;_from=R40&amp;rt=nc&amp;LH_TitleDesc=0
&gt;&gt; &gt;
&gt;&gt; &gt; Use the 555 module to switch this one as Russell suggests.
&gt;&gt; &gt;
&gt;&gt; &gt; Allen
&gt;&gt; &gt;
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[David C Brown]

Where would the power for the LED side of the opto-coupler come from?

<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
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__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by Manu Abraham
A quick suggestion: If you still want to use that module and still want
the isolation, connect an optocoupler to the control interface, which will
give an adequate isolation. Just that you will need to tinker with it.
Cheers,
Manu

Post by David C Brown
Thank you all for your advice. It is clear that this module is not safe
enough to use in the way I envisaged. I am now tending towards using
wireless remote control modules. Twenty feet of air, even humid air,

is a

Post by David C Brown
damn fine piece of isolation. :-)
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by RussellMc
That looks good as an example - BUT: any add on solution needs to be
checked to ensure that it fixes the isolation issue and does not have
issues of its own.
Russell

Post by Allen Mulvey
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0
Use the 555 module to switch this one as Russell suggests.
Allen

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[Manu Abraham]

From your control circuitry, of course. Or maybe a battery. Whatever

you can imagine.

If you need true isolation, consider a low power mini smps to power it.

Something of this sort:

https://www.amazon.com/HI-Link-HLK-5M05-Switching-Step-Down-Converter/dp/B077ZRWR5C

https://www.aliexpress.com/item/Hi-Link-ac-dc-power-module-5v-3w-220v-isolated-ac-dc-converter/32360232521.html



Cheers,
Manu

Where would the power for the LED side of the opto-coupler come from?
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__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by Manu Abraham
A quick suggestion: If you still want to use that module and still want
the isolation, connect an optocoupler to the control interface, which will
give an adequate isolation. Just that you will need to tinker with it.
Cheers,
Manu

Post by David C Brown
Thank you all for your advice. It is clear that this module is not safe
enough to use in the way I envisaged. I am now tending towards using
wireless remote control modules. Twenty feet of air, even humid air,

is a

Post by David C Brown
damn fine piece of isolation. :-)
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by RussellMc
That looks good as an example - BUT: any add on solution needs to be
checked to ensure that it fixes the isolation issue and does not have
issues of its own.
Russell

Post by Allen Mulvey
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0
Use the 555 module to switch this one as Russell suggests.
Allen

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[David C Brown]

I am more than capable of building from scratch using parts I already
have. But I am looking for a quick ready to go solution which is also safe.

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__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by Manu Abraham

From your control circuitry, of course. Or maybe a battery. Whatever

you can imagine.
If you need true isolation, consider a low power mini smps to power it.
https://www.amazon.com/HI-Link-HLK-5M05-Switching-Step-
Down-Converter/dp/B077ZRWR5C
https://www.aliexpress.com/item/Hi-Link-ac-dc-power-
module-5v-3w-220v-isolated-ac-dc-converter/32360232521.html
Cheers,
Manu

Where would the power for the LED side of the opto-coupler come from?
<https://www.avast.com/sig-email?utm_medium=email&utm_

source=link&utm_campaign=sig-email&utm_content=webmail>

Virus-free.
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source=link&utm_campaign=sig-email&utm_content=webmail>

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by Manu Abraham
A quick suggestion: If you still want to use that module and still want
the isolation, connect an optocoupler to the control interface, which

will

Post by Manu Abraham
give an adequate isolation. Just that you will need to tinker with it.
Cheers,
Manu

Post by David C Brown
Thank you all for your advice. It is clear that this module is not

safe

Post by Manu Abraham

Post by David C Brown
enough to use in the way I envisaged. I am now tending towards using
wireless remote control modules. Twenty feet of air, even humid air,

is a

Post by David C Brown
damn fine piece of isolation. :-)
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by RussellMc
That looks good as an example - BUT: any add on solution needs to be
checked to ensure that it fixes the isolation issue and does not have
issues of its own.
Russell

Post by Allen Mulvey
Enclosed Pre-Wired Relay
https://www.ebay.com/itm/RIB-Functional-Devices-RIBU2C-Enclo
sed-Pre-Wired-Relay-120-277VAC-10A/282946266423?epid=2261035
387&hash=item41e0e96537%3Ag%3AkTIAAOSwqxRa52aB&_sacat=0&_nkw
=enclosed+pre-wired+relay&_from=R40&rt=nc&LH_TitleDesc=0
Use the 555 module to switch this one as Russell suggests.
Allen

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[RussellMc]

Post by David C Brown
Thank you all for your advice. It is clear that this module is not safe
enough to use in the way I envisaged.

As previously noted, using it to operate a suitably specified relay will do
what you want. - and may be simpler and cheaper than many alternatives.


Russell

[David C Brown]

My main concern is that a failure of a resistor or capacitor in the 240vac
to 12vdc part of the circuit could put 240vac on the operating terminals
which will be connected to wiring and switches not rate for that voltage.

I fail to see how a relay on the output would address that problem.

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__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by RussellMc

Post by David C Brown
Thank you all for your advice. It is clear that this module is not safe
enough to use in the way I envisaged.

As previously noted, using it to operate a suitably specified relay will do
what you want. - and may be simpler and cheaper than many alternatives.
Russell
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