Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.
--
Bill

Bill wrote:
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

A triac would be a silent switch:
http://uk.farnell.com/stmicroelectro...p-3/dp/1057288
(heatsink may be required)

Use the relay to switch the gate of the triac, which will take basically no
current so less likely to rattle. You can also use a small
optocoupled-triac to drive the gate of the big triac for a fully solid-state
solution.
http://uk.farnell.com/triac-output-optocouplers

Theo

On Saturday, 17 December 2016 00:39:45 UTC, Theo wrote:
Bill wrote:

He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

A triac would be a silent switch:
http://uk.farnell.com/stmicroelectro...p-3/dp/1057288
(heatsink may be required)

Use the relay to switch the gate of the triac, which will take basically no
current so less likely to rattle. You can also use a small
optocoupled-triac to drive the gate of the big triac for a fully solid-state
solution.
http://uk.farnell.com/triac-output-optocouplers

Theo

Buzzing is not sue to current flowing in the switch, it's down to relay design. Mounting it on bits of rubber would help - its box can also be rubber washer mounted.


NT

On 17/12/16 00:08, Bill wrote:
Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

I decent relay should not be obviously noisy. Try an Omron brand from
RS/Farnell.

His immersion needs a relay capable of handling 13A resistive load AC at
mains voltage with a 230-250VAC coil.

Mains relays are noisy, but does it have to be a mains relay?
Could he just mot add a stage to his controller that could sink more
current into a dc one fed from a another supply.
Sounds like he is using the weedy switched supply in the controller to just
switch a mains relay. That is always going to buzz.

Brian

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

Blind user, so no pictures please!
"Bill" wrote in message
...
Son's house is wired so he can, via his iPhone and home wifi, control his
central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very temporary
measure he has wired it all up al fresco via the old immersion isolator
switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.
--
Bill

Ofr if you don't want that just rectify the mains and have a capacitor
across it and a different relay. There are lots of ways to do this in a less
clunky way.
Brian

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

Blind user, so no pictures please!
"Theo" wrote in message
...
Bill wrote:
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

A triac would be a silent switch:
http://uk.farnell.com/stmicroelectro...p-3/dp/1057288
(heatsink may be required)

Use the relay to switch the gate of the triac, which will take basically
no
current so less likely to rattle. You can also use a small
optocoupled-triac to drive the gate of the big triac for a fully
solid-state
solution.
http://uk.farnell.com/triac-output-optocouplers

Theo

In article ,
Bill wrote:

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

AC coil relays are more likely to make noise than DC types for obvious
reasons. But not all do. Where did you buy it? I'd expect one from RS
Components etc to be good.

--
*IF YOU TRY TO FAIL, AND SUCCEED, WHICH HAVE YOU DONE?

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

On Sat, 17 Dec 2016 10:12:33 +0000, Tim Watts wrote:

I decent relay should not be obviously noisy. Try an Omron brand from
RS/Farnell.

The Omron mains coil relays (MY21) I have are silent, well apart from
the click as they operate/release. B-)

His immersion needs a relay capable of handling 13A resistive load AC at
mains voltage with a 230-250VAC coil.

Not sure that they are rated at 13A resistive though wanders off to
find one nope 10A.

--
Cheers
Dave.

In article ,
Bill writes:
Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

This really needs a contactor rather than a plain relay, and
contactors can hum (so it might be that's what you already have).
As someone suggested, mounting it on some sort of soft rubber
mounts (and using loose flex wiring to the contactor) will help
prevent coupling to vibration to a sound board. Trying a different
mounting orientation might also reduce noise.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
"Brian Gaff" writes:
Ofr if you don't want that just rectify the mains and have a capacitor
across it and a different relay. There are lots of ways to do this in a less
clunky way.

Feeding an AC coil with DC will mean current is limited by the
resistance alone, and not by the coil impedance. This means the
coil will run hotter, hot enough to burn out in some cases.
(With small mains relays, the resistance is a significant portion
of the impedance, but resistance becomes less significant as
the relay coil size increases.)

The capacitor will also raise the RMS voltage from 240V up to
340V, and exactly double the coil power dissipation over the
240VDC case (which will already be higher than designed).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 12/17/2016 12:39 AM, Theo wrote:
Bill wrote:
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

A triac would be a silent switch:
http://uk.farnell.com/stmicroelectro...p-3/dp/1057288
(heatsink may be required)

Use the relay to switch the gate of the triac, which will take basically no
current so less likely to rattle. You can also use a small
optocoupled-triac to drive the gate of the big triac for a fully solid-state
solution.
http://uk.farnell.com/triac-output-optocouplers

Theo

Solid state relay, even easier?

http://www.ebay.co.uk/itm/SSR-40DA-S...AOSwoudW4mv q

Had a quick look at RS and they list several suitable - this one is about
a fiver:-

http://uk.rs-online.com/web/p/non-la...elays/8287211/

--
*Cover me. I'm changing lanes.

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

On 12/17/2016 1:10 PM, Andrew Gabriel wrote:
In article ,
Bill writes:
Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

This really needs a contactor rather than a plain relay, and
contactors can hum (so it might be that's what you already have).
As someone suggested, mounting it on some sort of soft rubber
mounts (and using loose flex wiring to the contactor) will help
prevent coupling to vibration to a sound board. Trying a different
mounting orientation might also reduce noise.

Standard 40 Amp solid state relay, available with low voltage or mains
switching. Been using them for years to control immersion heaters at my
mate's brewery. May need a small heatsink, depending on how and where
they are mounted. RS/Farnell for conservatives, eBay for cheapskates
like me.

On Saturday, 17 December 2016 10:12:38 UTC, Tim Watts wrote:
On 17/12/16 00:08, Bill wrote:
Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

I decent relay should not be obviously noisy. Try an Omron brand from
RS/Farnell.

His immersion needs a relay capable of handling 13A resistive load AC at
mains voltage with a 230-250VAC coil.

The immersion will draw much more than 13A when the element is cold.


NT

On 17/12/2016 14:15, newshound wrote:
On 12/17/2016 1:10 PM, Andrew Gabriel wrote:
In article ,
Bill writes:
Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

This really needs a contactor rather than a plain relay, and
contactors can hum (so it might be that's what you already have).
As someone suggested, mounting it on some sort of soft rubber
mounts (and using loose flex wiring to the contactor) will help
prevent coupling to vibration to a sound board. Trying a different
mounting orientation might also reduce noise.

Standard 40 Amp solid state relay, available with low voltage or mains
switching. Been using them for years to control immersion heaters at my
mate's brewery. May need a small heatsink, depending on how and where
they are mounted. RS/Farnell for conservatives, eBay for cheapskates
like me.

Do you find that the ebay ones are reliable?
There's a heck of a price difference between the ones from HongKong and
the ones from RS - £3 vs £40 (need 40A (probably) to switch 7kw load @ 240v.

I'm currently using a mains-driven contactor, that comes on with a
satisfying 'clunk' (and, sometimes, a whine/whistle) - but, if it (or
the ssr) were to fail 'closed' then that might get interesting rather
quickly... as it's feeding a resistive heater in a medium-sized glass kiln.

What's the failure mode of the ssr's - in your experience?
Thanks
Adrian

In article , Dave Plowman (News)
scribeth thus
In article ,
Bill wrote:

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

AC coil relays are more likely to make noise than DC types for obvious
reasons. But not all do. Where did you buy it? I'd expect one from RS
Components etc to be good.


Got some in use here Dave, all quiet..
--
Tony Sayer

In article ,
tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
In article ,
Bill wrote:

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.

AC coil relays are more likely to make noise than DC types for obvious
reasons. But not all do. Where did you buy it? I'd expect one from RS
Components etc to be good.


Got some in use here Dave, all quiet..

Got one here that came from Maplin many many years ago. Open frame type.
Used to switch the power to my AV setup via the switch on the main amp.
Only 10 amps, but more than enough. You can hear it make, but no buzz etc
after that. Must be getting on for 40 years old. ;-)

--
*This message has been ROT-13 encrypted twice for extra security *

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

On 12/17/2016 2:54 PM, Adrian Brentnall wrote:
On 17/12/2016 14:15, newshound wrote:
On 12/17/2016 1:10 PM, Andrew Gabriel wrote:
In article ,
Bill writes:
Son's house is wired so he can, via his iPhone and home wifi, control
his central heating etc. etc. from the train.
Not sure what system, but it has a controller for the heating and a
separate controller for the immersion.
The heating is OK, but he didn't read the spec and the immersion
took so
much current that the controller died.
He has now, with some drawings from me, wired in a 30A rated relay with
230v ac coil. I bought him a box to mount it in, but it apparently
isn't
decorative enough for his walk-in airing cupboard, so as a very
temporary measure he has wired it all up al fresco via the old
immersion
isolator switch.
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this
type
of relay is noisy, or whether anyone knows how to select a silent type.

This really needs a contactor rather than a plain relay, and
contactors can hum (so it might be that's what you already have).
As someone suggested, mounting it on some sort of soft rubber
mounts (and using loose flex wiring to the contactor) will help
prevent coupling to vibration to a sound board. Trying a different
mounting orientation might also reduce noise.

Standard 40 Amp solid state relay, available with low voltage or mains
switching. Been using them for years to control immersion heaters at my
mate's brewery. May need a small heatsink, depending on how and where
they are mounted. RS/Farnell for conservatives, eBay for cheapskates
like me.

Do you find that the ebay ones are reliable?
There's a heck of a price difference between the ones from HongKong and
the ones from RS - £3 vs £40 (need 40A (probably) to switch 7kw load @
240v.

I'm currently using a mains-driven contactor, that comes on with a
satisfying 'clunk' (and, sometimes, a whine/whistle) - but, if it (or
the ssr) were to fail 'closed' then that might get interesting rather
quickly... as it's feeding a resistive heater in a medium-sized glass kiln.

What's the failure mode of the ssr's - in your experience?
Thanks
Adrian

I used RS originally and, I think, had one fail after a couple of years.
Did a rebuild with eBay ones (not necessarily the cheapest), one channel
is currently down (there is redundancy) but I havn't confirmed if it is
the relay or some other fault.

I hadn't worried about protection. The whole system is powered dowm
before draining. Overheating caused by one failed channel would be
picked up by the brewer's manual check on water temperature. (This is a
hot liquor tank, for anyone interested). I suspect a single heater (3
kW) would not be able to get the tank to boiling point, but if it did
there is about eight feet of water to boil off before exposing elements!

newshound wrote:
Solid state relay, even easier?

http://www.ebay.co.uk/itm/SSR-40DA-S...AOSwoudW4mv q

As usual, they're a bit optimistic of the spec and the construction.
I don't think I'd want to put 30A through one.
Big Clive's teardown:
https://www.youtube.com/watch?v=DxEhxjvifyY

Theo

In article ,
writes:
The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sunday, 18 December 2016 11:24:00 UTC, Andrew Gabriel wrote:
In article ,
tabbypurr writes:

The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

1.414x 13A = 18.38A, well above the 13A rms current. If mains voltage goes to the upper end of its permitted range, the current will be higher again. So the OP needs a 20A relay at least.


NT

In article ,
Andrew Gabriel wrote:
In article ,
writes:
The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

Given very very few things draw constant current, I'd expect a relay rated
at 13 amps to cope with a higher switch on load? Although I've never
actually seen a relay rated at 13 amps. 15 would be more common.

--
*A chicken crossing the road is poultry in motion.*

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

In article ,
Dave Plowman (News) wrote:
In article ,
Andrew Gabriel wrote:
In article ,
writes:
The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

Given very very few things draw constant current, I'd expect a relay rated
at 13 amps to cope with a higher switch on load? Although I've never
actually seen a relay rated at 13 amps. 15 would be more common.

Indeed so. 13A is a very British thing. Most other countries in Europe
think about 15A - or even 16A.

--
from KT24 in Surrey, England

On 18/12/2016 12:42, wrote:

1.414x 13A = 18.38A, well above the 13A rms current. If mains voltage
goes to the upper end of its permitted range, the current will be
higher again. So the OP needs a 20A relay at least.

Nonsense! Calculating the repetitive peak current is irrelevant. Relay
current ratings are RMS values. An immersion heater is a very benign
load - it's AC-21 service [1] with no significant inrush current. A 16
A relay of reputable manufacture should be fine, assuming any sensible
number of switching events per day/hour.

[1] https://en.wikipedia.org/wiki/Utilization_categories

--
Andy

In message ,
newshound writes
Standard 40 Amp solid state relay, available with low voltage or mains
switching. Been using them for years to control immersion heaters at my
mate's brewery. May need a small heatsink, depending on how and where
they are mounted. RS/Farnell for conservatives, eBay for cheapskates
like me.

Do you find that the ebay ones are reliable?
There's a heck of a price difference between the ones from HongKong and
the ones from RS - £3 vs £40 (need 40A (probably) to switch 7kw load @
240v.

I'm currently using a mains-driven contactor, that comes on with a
satisfying 'clunk' (and, sometimes, a whine/whistle) - but, if it (or
the ssr) were to fail 'closed' then that might get interesting rather
quickly... as it's feeding a resistive heater in a medium-sized glass kiln.

What's the failure mode of the ssr's - in your experience?
Thanks
Adrian

I used RS originally and, I think, had one fail after a couple of
years. Did a rebuild with eBay ones (not necessarily the cheapest), one
channel is currently down (there is redundancy) but I havn't confirmed
if it is the relay or some other fault.

I hadn't worried about protection. The whole system is powered dowm
before draining. Overheating caused by one failed channel would be
picked up by the brewer's manual check on water temperature. (This is a
hot liquor tank, for anyone interested). I suspect a single heater (3
kW) would not be able to get the tank to boiling point, but if it did
there is about eight feet of water to boil off before exposing elements!

OK, OP here. I'm going to suggest rubber mounting of the existing relay
inside a box and see what happens. I think his relay is from China via
ebay, so a better quality one might buzz less.

Searching for mains to mains SSR found this
http://www.conch.com.tw/index.php?op...sk=showinfo&id
=31636

but I haven't found a UK supplier.

Most of these SSR's seem to be lowish voltage DC input and I don't think
I want to have him doing calculations and assembling rectifiers and
voltage dividers.
--
Bill

On 18/12/2016 12:55, charles wrote:
In article ,
Dave Plowman (News) wrote:
In article ,
Andrew Gabriel wrote:
In article ,
writes:
The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

Given very very few things draw constant current, I'd expect a relay rated
at 13 amps to cope with a higher switch on load? Although I've never
actually seen a relay rated at 13 amps. 15 would be more common.

Indeed so. 13A is a very British thing. Most other countries in Europe
think about 15A - or even 16A.


And?

It's called Great Britain for a reason.

There is no such place as Great France or Great Germany.





--
Adam

On 18/12/2016 11:22, Andrew Gabriel wrote:
In article ,
writes:
The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

EICR on a rented property

Got a few odd readings.

I then asked "Do you want me to test the cannabis factory in in loft?

--
Adam

"ARW" wrote in message
...
On 18/12/2016 12:55, charles wrote:
In article ,
Dave Plowman (News) wrote:
In article ,
Andrew Gabriel wrote:
In article ,
writes:
The immersion will draw much more than 13A when the element is cold.

No they don't.
Nichrome resistance doesn't change anything like that of tungsten,
and in any case, the temperature change is only a small fraction
of that of a tungsten filament.

Given very very few things draw constant current, I'd expect a relay
rated
at 13 amps to cope with a higher switch on load? Although I've never
actually seen a relay rated at 13 amps. 15 would be more common.

Indeed so. 13A is a very British thing. Most other countries in Europe
think about 15A - or even 16A.


And?

It's called Great Britain for a reason.

Yep
https://en.wikipedia.org/wiki/Great_...of_.22Great.22

There is no such place as Great France or Great Germany.

Because that reason doesn’t apply to them.

In article ,
Bill wrote:
OK, OP here. I'm going to suggest rubber mounting of the existing relay
inside a box and see what happens. I think his relay is from China via
ebay, so a better quality one might buzz less.

Searching for mains to mains SSR found this
http://www.conch.com.tw/index.php?op...sk=showinfo&id
=31636

but I haven't found a UK supplier.

I gave a link to one from RS earlier. I'd guess CPC and others will have
similar.

Most of these SSR's seem to be lowish voltage DC input and I don't think
I want to have him doing calculations and assembling rectifiers and
voltage dividers.

I'd personally not use an SSR for this. They are more expensive and very
much more likely to fail in practice.

--
*In "Casablanca", Humphrey Bogart never said "Play it again, Sam" *

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

On Sat, 17 Dec 2016 00:08:15 +0000, Bill wrote:

snip
He reports that it all works well except for the buzzing from the relay
coil, which is bound to get louder when it's mounted in a box on the
wall.

I have said I'll ask around to see if anyone knows whether all this type
of relay is noisy, or whether anyone knows how to select a silent type.


Virtually all AC coil relays are noisy to some extent, but some are worse
than others. For your son's situation I would recommend using a modular
relay. These clip directly onto DIN rail and can be fitted into a
consumer unit or anything similar. They are virtually silent.

Something like this: http://cpc.farnell.com/finder/22-22-8-230-4000/relay-
modular-2n-o-230vac/dp/SW03915