Removing a relay

boris1 · May 22, 2021

I'm trying to learn more about relays.
Can someone link to a resource that describes how they work? I mean like a wiring diagram of 1L1 3L2 5L3 2T1 4T2 6T3...
Here is a LC1K09 that is connected to a lighting circuit.
What are the alternative ways to remove/disconnect it and instead have the switching done manually?
By manually I mean either with a circuit breaker or wall switch.

[ElectriciansForums.net] Removing a relay

DPG · May 25, 2021

boris1 said:
What would you do? They are all like that: LC1K09 - Recherche Google - https://www.google.com/search?q=LC1K09&client=safari&rls=en&source=lnms&tbm=isch&sa=X&ved=2ahUKEwji18On4uTwAhXjCRAIHa9BBvAQ_AUoAXoECAEQAw&biw=987&bih=689

This is the consumer unit, it’s out of reach of children and I think most people know not to mess around in there. If someone really wanted to, they could stick a fork/knife into the screws and get all those 400 volts. The screws are not covered either (just depressed when they are screwed in.

'It's kind of out of reach'
'Most people know not to mess with it'

Not phrases I would expect to hear relating to 3 phase 400V equipment that people are using to switch some lights on and off!

timhoward · May 25, 2021

boris1 said:
What would you do? They are all like that

This is the consumer unit, it’s out of reach of children and I think most people know not to mess around in there. If someone really wanted to, they could stick a fork/knife into the screws and get all those 400 volts. The screws are not covered either (just depressed when they are screwed in.

In terms of UK regulations "Basic Protection" is first on the list, and I'd be looking at moving the relays into an enclosure, or very carefully weighing up the requirements of using the "placing out of reach" method of basic protection, which probably wouldn't be appropriate in this case and is often hard to meet.

(I made the mistake 20 years ago of naively thinking that just because a consumer unit uses a DIN rail, anything designed for a DIN rail could go in it. In that it was case a contactor for storage heaters in a commercial workshop. It also poked out of the front, exposing live parts. I showed someone a photo of it, proud of my work, and got torn to shreds, and did 16th edition soon after)

Anyway, I'd be quite surprised if the current installation meets local requirements and unless you are 100% sure it is compliant I'd seek a second opinion.

boris1 · May 25, 2021

timhoward said:
In terms of UK regulations "Basic Protection" is first on the list, and I'd be looking at moving the relays into an enclosure, or very carefully weighing up the requirements of using the "placing out of reach" method of basic protection, which probably wouldn't be appropriate in this case and is often hard to meet.

(I made the mistake 20 years ago of naively thinking that just because a consumer unit uses a DIN rail, anything designed for a DIN rail could go in it. In that it was case a contactor for storage heaters in a commercial workshop. It also poked out of the front, exposing live parts. I showed someone a photo of it, proud of my work, and got torn to shreds, and did 16th edition soon after)

Anyway, I'd be quite surprised if the current installation meets local requirements and unless you are 100% sure it is compliant I'd seek a second opinion.

There may be a misunderstanding because I didn’t show the picture of the enclosure.
It has a lid like any other and they even added a lock to it. It passed the local regulations and has been installed like this for about 12 years (when that wireless Schneider Connect switch was implemented).
I don’t think anyone would go trying to switch a contractor indicator switch but I suppose it would be good to put that little switch and the screws behind some plastic covers. Hint to the electric manufacturers?

DPG · May 25, 2021

Ah, so there is a lid fitted which requires a screwdriver to open it? But how do they operate the MCB to switch the lights on and off?

timhoward · May 25, 2021

boris1 said:
There may be a misunderstanding because I didn’t show the picture of the enclosure.

Yes, in my mind that is a "cover of any description" and considerably safer than I was fearing.

dodger421 · May 25, 2021

Schneider (and others) make taller contactors specifically for this job. They sit on the din rail as normal but the terminals are all covered by the DB/CU enclosure.

boris1 · May 25, 2021

dodger421 said:
Schneider (and others) make taller contactors specifically for this job. They sit on the din rail as normal but the terminals are all covered by the DB/CU enclosure.

Thanks. I’ll bookmark that one.

boris1 · May 25, 2021

DPG said:
Ah, so there is a lid fitted which requires a screwdriver to open it? But how do they operate the MCB to switch the lights on and off?

I don’t have a better picture and must apologise for the previous poorly worded post. I meant the hinged door has a lock to keep “unauthorised” people away. But below the hinged door (which is not visible in the picture) is the lid which does not need to be unscrewed and removed to operate the MCBs as you can see.
It’s been rewired now to have a “controller” MCB control the contactor/relay. I told them to be dry when they’re operating the MCB.

DPG · May 25, 2021

boris1 said:
I don’t have a better picture and must apologise for the previous poorly worded post. I meant the hinged door has a lock to keep “unauthorised” people away. But below the hinged door (which is not visible in the picture) is the lid which does not need unscrewing to operate the MCBs as you can see.
It’s been rewired now to have a “controller” MCB control the contactor/relay. I told them to be dry when they’re operating the MCB.

So to confirm things, because this is hard to follow, they switch the lights on and off using an MCB which is near the contactors which have the exposed screws?

Why can't they have a 'proper' switch after the MCB?

boris1 · May 25, 2021

DPG said:
So to confirm things, because this is hard to follow, they switch the lights on and off using an MCB which is near the contactors which have the exposed screws?

Why can't they have a 'proper' switch after the MCB?

The MCB is in the top row. The relays are in the middle row. By "exposed screws” I meant the relay L & T screw. They’re not really super-exposed since they’re below the surface.
I was just trying to make the point that if someone really wanted to, then they could stick a knife/fork in there just like one could stick a knife/fork in an outlet.

boris1 · May 25, 2021

DPG said:
So to confirm things, because this is hard to follow, they switch the lights on and off using an MCB which is near the contactors which have the exposed screws?

Why can't they have a 'proper' switch after the MCB?

Yes, that’s what I recommended! And that’s what the Schneider Connect wireless switch used to do (with the receiver tucked away into a plastic junction box in the dropped ceiling). But they didn’t want to spend the money on a new Connect switch or even a cheap NEXA 433Mhz wireless switch and receiver. This way, they save 40 euros and just use the MCB once a week when they need it.

DPG · May 26, 2021

boris1 said:
Yes, that’s what I recommended! And that’s what the Schneider Connect wireless switch used to do (with the receiver tucked away into a plastic junction box in the dropped ceiling). But they didn’t want to spend the money on a new Connect switch or even a cheap NEXA 433Mhz wireless switch and receiver. This way, they save 40 euros and just use the MCB once a week when they need it.

I know, but why not just connect a standard (non wireless) switch after the MCB? Then they don't have to poke around in a tricky to access panel.

boris1 · May 26, 2021

DPG said:
I know, but why not just connect a standard (non wireless) switch after the MCB? Then they don't have to poke around in a tricky to access panel.

It's a unique situation in that the wireless receiver was in a junction box in the ceiling trunking/cable tray in a section of the premises where they cannot have a switch due to customer access.

DPG · May 26, 2021

boris1 said:
It's a unique situation in that the wireless receiver was in a junction box in the ceiling trunking/cable tray in a section of the premises where they cannot have a switch due to customer access.

Is there no room at all next to the dist board to fit a switch?

boris1 · May 26, 2021

DPG said:
Is there no room at all next to the dist board to fit a switch?

Just as the wireless receiver, the CU / distributing board is in the same section of the shop where they cannot have customers accessing the switch. I suppose I could have built some sort of cage with lock around the switch but that would cost even more than a new wireless switch for which they were already unwilling to pay.

Removing a relay

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