Changing original 32Amp contactors for solid state relays?

[Yonny24]

Hi Guys,

My underfloor heating has 3 x 32amp contactors. They make a hell of a thump when opening and closing. Bit of a hum also.

I'm looking at the idea of changing them for solid state relays like this one Solid State Relay - 40A (3-32V DC Input) - COM-13015 - SparkFun Electronics - https://www.sparkfun.com/products/13015

Will these work? I'd need to source a 12v switching supply instead of the current 220v. Easily done as I have plenty of 220-12v power supplies handy.
I assume they are much quieter and can be switched endless times without any physical parts wearing out.

Thanks in advance

 

[Lucien Nunes]

In theory, yes. You can also get types with 230V AC control input. Depending on the current they are switching, a heatsink may be required as unlike a contactor, there is a small voltage drop across the power device that results in some heat dissipation (although, there's no heat dissipation from the control side as there is in a contactor coil.) Read the data sheet. Depending on the supply voltage, likelihood of voltage spikes and the nature of the load (yours is resistive and therefore should be tame) snubbers and/or transient voltage suppression might be recommended.

My experience with power semiconductor devices is that you get what you pay for. I don't know about the particular product in your link but an industrial SSR of that rating, that I would be happy to rely on, is typically more expensive.

 

[marconi]

You might want to investigate 'silent contactors' to replace your present ones. Here is an example:

View: https://www.amazon.co.uk/Hager-Esc440s-Silent-Contactor-40a-4no-230/dp/B0062X1D2I


These use the usual mains supply voltage to power their coils. Other manufacturers make them too. You may still hear briefly the closing or opening events but once closed they are quieter than normal types.

 

[Yonny24]

You might want to investigate 'silent contactors' to replace your present ones. Here is an example:

View: https://www.amazon.co.uk/Hager-Esc440s-Silent-Contactor-40a-4no-230/dp/B0062X1D2I


These use the usual mains supply voltage to power their coils. Other manufacturers make them too.

Thanks .

That's the one I have for the upstairs floor heating.
Yes it is silent. 40 amp model for all the heating upstairs.

Downstairs we have 3 contactors of 32 amps each but I don't think they consume more than 5000 watts in total. (230v).


5000 watts would be 22 amps in total. hmmm why have 3 x 32 amps? (maybe just what they had and the max amperage is not that important)
Wouldn't one or 2 of these be sufficient in the placement of the 3 noisy contactors?

Also the power prior to the contactors come from 3 x 20amp trip switches.

Thanks for the replies today
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I see the types of heat sinks available now.

View: https://www.amazon.co.uk/SSR-40-3-32V-24-380V-Solid-State/dp/B07JQ2S3Z9/ref=pd_sbs_328_6/259-1440324-8968235?_encoding=UTF8&pd_rd_i=B07JQ2S3Z9&pd_rd_r=2d4cd923-0e7c-478f-b7a4-b92b29eeb364&pd_rd_w=87mxm&pd_rd_wg=XGJ4t&pf_rd_p=2773aa8e-42c5-4dbe-bda8-5cdf226aa078&pf_rd_r=X4E4Y1A3XRD1EP9X00WG&psc=1&refRID=X4E4Y1A3XRD1EP9X00WG


I wonder is 16 amps through a 40amp version will keep cool without a heatsink?

 

[marconi]

A wiring drawing and some pictures would be helpful plus exact numbers for the Ipower of under floor heating pads, cables, tiles. Please include the thermostats. This will help folk advise you.

 

[Yonny24]

Here we have the ground floor contactors. 4 thermostats (cheap copies of Honeywell and do not work well at all). Installing a central digital thermostat that will send a signal to the sonoff switch in the fuse box.

Living room
Dining room
Breakfast room and kitchen (2 zones).

Living room about 11-12m2 consumes about 2000 kwh.
Dining room a little less and kitchen/breakfast about 1800 combined.

No more than 6000 kwh. (230v)

Would it be possible to swap out the 3 contactors here for 1 x 4 pole new contactor? How would this be wired? You see we have 2 Lives/ 1 Neutral cable set up coming in.
I see 3 sets of L/N cables going out to each of the 3 zones. I recently added the meters.

 

[marconi]

Could you take a couple more photos? One looking down on the black bar across the top of the 20A circuit breakers and one looking up to the contactors, timer and power meters?

It looks to me that the power meter and the time switch are unused - am I correct?

The wiring looks somewhat quirky so the extra photos will be helpful.

Who wired this up?

 

[Yonny24]

Many thanks Marconi. Appreciate your time.

The timer on the right is now unused. Just the L/N being taken from the inputs to power the Sonoff R3 wifi switch on the left that I added this week to control the contactors. Much easier to set times and control virtually.

The 3 slim power meters I added are in use as I'm currently calculating the costs and making notes of daily use. They are wired in between the 20amp breakers and the contactors. (They are upside down as the inputs were on the bottom oddly). Sorry the double cabling (2 x 2mm) was used on the meters as I did not happen to have any 3mm in the house. I'll get around the changing those and making it all neater once the lockdown is over.

The original wiring with the breakers and contactors was all done by the underfloor heating company 'EuroCable' 10 years ago when the house was constructed.

Struggled at first to figure out the L1/L2/N 3 wire cabling config.

Thanks again

 

[marconi]

Sir- could you tell me please what qualifications and experience you have with this type of wiring and electrical accessories?

What I am seeing looks 'confused'. For example the power meters look to be wired across the 20A circuit breakers. The wiring arrangement of the top row of disconnector and 5 circuit breakers is as I said before quirky. And I cannot fathom why you reckon you have an L1, L2 and N power supply. There are other anomalies.

 

[Yonny24]

Sir- could you tell me please what qualifications and experience you have with this type of wiring and electrical accessories?

What I am seeing looks 'confused'. For example the power meters look to be wired across the 20A circuit breakers. The wiring arrangement of the top row of disconnector and 5 circuit breakers is as I said before quirky. And I cannot fathom why you reckon you have an L1, L2 and N power supply. There are other anomalies.

No qualifications but many years experience of building valve amps/rebuilding transistor amps, home electrics also over the last 20 odd years.

The output of each 20a circuit breaker is wired to the meter and the output of the meter goes into the contactor.

The original cables (The thick white and brown cables) that were between the 20a breakers and contactors were just swapped over to the power meters inputs - nothing changed there.

230v, 209v, 23v - readings from ground to main cabling entering the main breaker.

Thanks

 

[marconi]

What is that black bar along the top of the 5 cbs? It looks like it connects together the top five terminals and is supplied by 3 white wires from under the disconnector connected to its terminals N, L1 and L2.

And a thin Blue (neutral) connects to the underneath terminal of the second from right cb which seems odd to me.

Could you point out to me the main neutral entering and being distributed please?

Are those five cbs double pole types?

Where did you measure those voltages you mentioned in #10?

 

[Yonny24]

ok adding some original photos here of the previous original wiring.
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What is that black bar along the top of the 5 cbs? It looks like it connects together the top five terminals and is supplied by 3 white wires from under the disconnector connected to its terminals N, L1 and L2.

And a thin Blue (neutral) connects to the underneath terminal of the second from right cb which seems odd to me.

Could you point out to me the main neutral entering and being distributed please?

Where did you measure those voltages you mentioned in #10?

What is that black bar along the top of the 5 cbs? - Not sure that was original - appears to apply the power across all 5 cbs from all 3 cables as if they are all live. Yes from the 3 white wires from the main breaker.
I have the same upstairs.

That small blue wire suppliers the Live/positive to the timer.
The 3rd white cable coming into the main breaker is the one with 23v to ground. I haven't gotten my head around the 3 cable config yet. You can see they've used the small white wire from the final 20a breaker to supply the neutral for the timer.

I measure those voltages from the ground bus to the 3 main contacts on the 1st main breaker top left.

Original timer on the right was connected from the bottom outlets to each contactor. I removed the outputs as I have the sonoff now on the left.

Hope this helps. If you need more photos/details please ask.
Maybe Uruguayan standards?? I'm an expat from the UK so was odd for me.

Thanks again

 

[marconi]

Thank you. I am being careful to understand how it is wired now. Eventually I will produce a drawing.
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Could you , with great care, study your main consumer unit and establish where the group of three whites above the did connector are supplied from and post a picture. Don,t go sticking your fingers it tools inside to do this. Can you also identify the neutral for the under floor heating and what it connects to. Last take a picture of your main electricity meter(s).

 

[Yonny24]

ok let me try this.

The 3 white cables are wired from an identical adjacent fuse box. These are fed from an identical main breaker (did?). All in the same sequence. Other breakers to supply lights/sockets etc come from the first fuse box.

The main cable coming into the house has these 3 cables feeding into the did/breaker.
Outside we have a breaker at the front gate. The 3 red wires shown are the ones that come into the 1st main fuse box - same sequence again and then into the second box for the floor heating.

Not sure about the neutral.

I can see from the thermostats the cables from the contactors are fed onto the 1st and 2nd screws (must be live and neutral, left live, right neutral). Behind the thermostat you see the orange cables that must be leading to the floor. These do not have a floor thermostat, just air. Looks like the main white connects to the orange and the other orange to the blue. Live and neutral.

4 thermostats here. 2 from one contactor 'kitchen' must be in series, 1 for the living room, and one for the dining room.
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Been studying the house for some months now. We moved in last year.
been installing cat6 through the conduits, changing all the wall sockets, adding intelligent lights switches and routers etc.

Found a lot of odd things. Don't even ask me about the main grounding of the house and pool area! All fixed now luckily.

 

[marconi]

Any chance of a picture of your meter(s)?

 

[Yonny24]

Other side of the wall. Thick Grey cable is the supply from the overhead street cables.

 

[marconi]

It must be getting late where you are. So one last photo please looking up underneath the meters to see the individual wires going into it. Then I will leave you be until tomorrow. I am going to cook some minty lamb mince Devon pasties.


Not 'did' - meant to type disconnector or main breaker if you prefer.

Where are you in Uruguay? I am in London.

 

[Yonny24]

Sounds tasty. Miss many things from the UK.
We're 4 hours behind the UK so on my lunch break now. Work remotely here.
I live in Barra de Carrasco, Canelones. Just outside Montevideo.
Tricky to take photos as the meter is in a big sealed box with a small window just big enough to get my hand in.

Bon Appétit or buen provecho.
Regards

 

[marconi]

Good morning. I will start to produce some drawings today. First though please tell me the colours of the wires in the thick supply cable under the meter.

From the meter box it looks like 3 reds head out to your home and no other wires - is this correct? What colours do they connect to at the meter? If you cannot say then please make a drawing for me.

There is also a terminal schematic on the plastic cover over the meter terminals which I cannot see completely - could you draw or photo it and mark up where the wires of the supply and the 3 reds connect to?

 

[marconi]

Observations 1

a. If one studies Drawing 1 attached, one can observe that through the 4 pole disconnector (top left) and then the 3 white wires to above the 5 circuit breakers all the 3 white wires top left are joined together by the black busbar. This means these three white wires top left cannot be L1, L2 and N because a short circuit would have occurred rupturing a fuse or tripping a circuit breaker external to this enclosure. If a short circuit has not happened then they more likely to be of the same potential ie: a line or a neutral. The N, L1, L2 and L3 markings on the disconnector are to inform how it should be connected to such a supply if presented to it.

b. Studying further, one can readily see that each of the 2 wire digital power meters are connected across a 20A circuit breaker - this is incorrect. When the circuit breaker is closed the input to the power meter is short circuited and will not read any power consumption. In addition, the power meter requires an L and N at its input where only an L or N (yet to be confirmed) has actually been connected. I note the meters are reading zero.

c. The output side of the power meter connects to the input of a contactor by the blue and white wires and then from the output of each contactor to the floor heating elements ( I assume at this stage). Because only an L or an N (yet to be confirmed) is provided at the input to each contactor then no supply voltage will ever be connected across the elements - therefore they will not heat up. I suspect then that the underfloor heating system does not work at all at the moment.

d. The timer, albeit now redundant, still has two wires to it presumably intended as its supply - blue and white. Since these are derived wrongly from the two circuit breakers on the far right whose inputs are connected together by the black busbar there will be no voltage supply applied to the timer - it will not function.

e. From d), since the wifi switch has been tapped off the input to the timer it too has not voltage supply and will not function.

f. it would be impossible to measure with respect to earth the three voltages 230, 209 and 23V at the input terminals to the disconnector while it was closed because as mentioned when the disconnector is closed all the two sets of 3 white wires are at the same potential because of the black busbar.

It looks to me then that the wiring for the UFH was wrong from the very start or changes have been made which have resulted in a completely incorrect arrangement. Do you know the history of the UFH - did it ever work?

 

[Yonny24]

Observations 1

a. If one studies Drawing 1 attached, one can observe that through the 4 pole disconnector (top left) and then the 3 white wires to above the 5 circuit breakers all the 3 white wires top left are joined together by the black busbar. This means these three white wires top left cannot be L1, L2 and N because a short circuit would have occurred rupturing a fuse or tripping a circuit breaker external to this enclosure. If a short circuit has not happened then they more likely to be of the same potential ie: a line or a neutral. The N, L1, L2 and L3 markings on the disconnector are to inform how it should be connected to such a supply if presented to it.

b. Studying further, one can readily see that each of the 2 wire digital power meters are connected across a 20A circuit breaker - this is incorrect. When the circuit breaker is closed the input to the power meter is short circuited and will not read any power consumption. In addition, the power meter requires an L and N at its input where only an L or N (yet to be confirmed) has actually been connected. I note the meters are reading zero.

c. The output side of the power meter connects to the input of a contactor by the blue and white wires and then from the output of each contactor to the floor heating elements ( I assume at this stage). Because only an L or an N (yet to be confirmed) is provided at the input to each contactor then no supply voltage will ever be connected across the elements - therefore they will not heat up. I suspect then that the underfloor heating system does not work at all at the moment.

d. The timer, albeit now redundant, still has two wires to it presumably intended as its supply - blue and white. Since these are derived wrongly from the two circuit breakers on the far right whose inputs are connected together by the black busbar there will be no voltage supply applied to the timer - it will not function.

e. From d), since the wifi switch has been tapped off the input to the timer it too has not voltage supply and will not function.

f. it would be impossible to measure with respect to earth the three voltages 230, 209 and 23V at the input terminals to the disconnector while it was closed because as mentioned when the disconnector is closed all the two sets of 3 white wires are at the same potential because of the black busbar.

It looks to me then that the wiring for the UFH was wrong from the very start or changes have been made which have resulted in a completely incorrect arrangement. Do you know the history of the UFH - did it ever work?

Wow thanks for your detailed reply.
I'll reply to a few of the points and look into it in more detail later and get back to you.

b - The meters are working perfectly. They measure 230v across the input terminals and 230v across the outputs. They turn over and the green light flashes red when current is flowing through. The dining room was turned on last night and used 2000 kwh. Now reading 5.1 kw

c- the outputs of the meters read 230v (across the white and blue terminals) and feed the contactors. These heat up when the timer activates them. All the floor heating works.

d- the original timer on the right also has 230v across the blue and white wires. This has always worked and did switch on the contactors before I switched the timer over to the sonoff.

f- I measured the 3 voltages with respect to earth at the input of the main breaker (3 white wires).

Every contactor's input terminals has 230v across the white and blue wires and also across the output terminals when switched on (and they get hot).

Sorry to throw a spanner in the works.
I'll have a look at the external meter box later and get back to you.

Many thanks

 

[marconi]

That means then that what I see in the photos is inaccurate. Could you draw the wiring for me to study?

Could you confirm (safely) what the black bar along the 5 cbs is and does? Does it connect together all the top terminals?

Does the group of three whites under the disconnector go to above the 3 left side cbs.

 

[Yonny24]

That means then that what I see in the photos is inaccurate. Could you draw the wiring for me to study?

Could you confirm (safely) what the black bar along the 5 cbs is and does? Does it connect together all the top terminals?

Does the group of three whites under the disconnector go to above the 3 left side cbs.

Your drawing is fine - just the brown and white wires entering the power meters are the other way around. White entering the left terminal and brown entering the right terminal. Everything else matches up.

The black bar along the cbs just appears to join all the cables across which I find odd.
All 3 live power cables?? This will all installed by the authorised national electricity company here, UTE, to their standards.


Yes the group of white wires under the disconnector go above to the 3 cbs in the same sequence also. Left to right.

 

[marconi]

Only if you feel safe to do so - would you measure and report the voltages at each of the top three terminals ( 1, 3, 5) of the disconnector to earth and then do the same for the corresponding bottom 3 terminals ( 2 , 4 ,6 )? Ac voltage and a scale to read at least 230V.

 

[Yonny24]

Only if you feel safe to do so - would you measure and report the voltages at each of the top three terminals ( 1, 3, 5) of the disconnector to earth and then do the same for the corresponding bottom 3 terminals ( 2 , 4 ,6 )? Ac voltage and a scale to read at least 230V.

Will do.
Yes I feel safe to do this. I've worked with valve amps, 500v transformers for power outputs and high amperage power supplies for valve heaters etc, and 400+v caps for years. These caps pack a punch even when disconnected. I know what it's like to get a shock and not pleasant (or safe). A charged disconnected cap can cause a lot of pain.
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Only if you feel safe to do so - would you measure and report the voltages at each of the top three terminals ( 1, 3, 5) of the disconnector to earth and then do the same for the corresponding bottom 3 terminals ( 2 , 4 ,6 )? Ac voltage and a scale to read at least 230V.

1 (top 1st terminal) - 258
3 (top 2nd terminal) - 28
5 (top 3rd terminal) - 240

2 (bottom 1st terminal) - 214
4 (bottom 2nd terminal) - 26
6 (bottom 3rd terminal) - 238

All measured to ground.