Dear John, i know this video is a few years old but having come across this board for the first time this week your presentation was a god send. I could not for the life of my locate the current rating on these old MCB's until I watched your programme - great work again. Thanks Robert - semi-retired but still plodding along.
Square D was bought out by "Schneider Electric" a few years ago... Square D is popular here in Canada and the "QO" series is by far one of the top breakers around... From what I see, those "QO-E" ( European version I assume?) would interchange with what we have here, and vice-versa..
In later years you could get RCD/CB's for the Crabtree C50 boards. Each one would take up the room of two standard breakers and were fitted in exactly the same way.
Crabtree polestar are the same way... two positions but only one is used for feeding power. Is the C50 style also 'split' into two seperate breaker levers so you can tell whether the fault was overcurrent or earth fault? Fitted one (new old stock, lol) this morning to provide RCD protection on socket circuits on an installation dating from the late 80s or early 90s
I have installed a few of the Crabtree CUs when I first started back in the late eighties, and no torque screwdriver required , that thing make the modern crap we’ve got now look silly in terns of quality, theses days it all about safety over quality. I love all this old fashioned stuff. Brilliant video JW as always 👍👍
The offshore gas production platform I work on in the North Sea has lots of these Square D boards. All three phase and from my opinion very well built. They have been in use since the early 90's with very few issues. We can still get replacements via the company that took them over however they are quite expensive. In-fact we also have RCBO's from the original install in these and they are type 'A' which in the UK we are now only just now getting up to speed with. I assume they would have been supplied from the States who I believe adopted this tech far earlier than we did in the U.K.
Here in South Africa we went from fuses ( still legal as grandfathered in for when the house was built) to clip in Fuchs and Heinemann ( later Hymag) thermal and magnetic breakers. Only thing you have to do on change of ownership or any upgrade ( replace like for like is not an upgrade, but changing out a 5A round pin socket to a 15A socket still on the existing 2.5mm DCC wire (scary) is classed as an upgrade) requires the upgraded section to comply with the current regulations, so you might find a house with a fuse box with replaceable wire fuses ( often with 2.5mm copper wire as fuse element as that does not blow) and then for the new section you will have next to it a surface mounted box with RCD and breakers, all next to the big wooden panel in the kitchen that holds the electricity meter, with the old cotton covered wiring leading up into the roof space where it runs along to the eave and goes out the side in a pitch filled pipe to the 3 wire overhead line to a street pole. Ground is a 6mm bare wire run next to these, and an additional 6mm wire to a galvanised cold water pipe or to an earth rod outside the kitchen door. The fitting of a RCD and an accessible non hidden mains switch is mandatory on change of ownership however on all houses, so there might be a tiny 4 way box with a RCD only in it and a label on the kitchen wall, the rest being inside a kitchen cupboard and most commonly right above the stove. There have even been some homeowners who saved cost by only replacing the live wire in the conduit with PVC so the RCD will not trip, leaving the old neutral as DCC and the conduit providing the ground connection. May pass insulation test ( as that typically only looks at the line side and not the neutral) but not a good thing.
@ John Ward, It's strange how the design of them switchboards, almost seems to mimic the later DIN Rail technology. I've worked on the NZ equivalent of the Crabtree, as in Gael switchboards, they were made more for Industrial and Commercial installations. With the circuit-breakers you were showing, was there an option to inter-link 3 circuit-breakers on a given circuit? I do know that there was a captive link you could get for the Gael circuit-breakers. I don't miss the live exposed busbars though, especially when there were 3 of them. Thanks for the great video.
Hey John, could you explain your view on why you always refer to the live phase as a "Line" connection, versus the commonly (and I assume incorrectly) used term "Live". My guess at what's behind your thinking here is that even Neutral or Earth connections are still effectively and potentially "Live" (as in phase hot) connections in an active circuit, and so should always be considered as being "Live", versus "Line" being specifically the phase supply of a circuit as differentiated from a Neutral or Earth connection. Am I on the mark here?
+9ff70f96 Yes, it was redefined fairly recently so that the conductors are line & neutral, with 'live' referring to any conductor that carries current in normal operation, so live includes both line and neutral.
Just a quick question, do you know the current rating of the main switch in the Crabtree C50 distribution board you had? I had to inspect a property yesterday with that exact 6 way DB in it.
Hi John I seem to remember that the regulations stated that heavy load should be at the main switch. As the shower circuit breaker has been added at a later time perhaps more thought into where the breaker should be placed.
I think that's a bit of a myth. The busbar should be able to handle the full load current at the far end. But it's a practice so common as to be considered 'rules' to put the larger breakers to the feed end
John, do you still have the Square D CU? As others have noted, it bears striking similarity to the "QO" line marketed in the US market. If you've still got it, and would be willing, I'd like to ship you a few breakers to see if they really are compatible, or if Schneider/SqD altered some spacing to prevent them from fitting...
+John Ward I've never seen a C50 in a domestic installation but I guess that's because it would have cost more than a 3036 Wylex... The C50's 3kA breaking capacity is well specc'd in comparison. Do the C50 breakers say what trip curve they are?
Picked up some old switches from a rewire this week.... don't know if I can send a pic to see if u can date them and also would they still comply to be e refitted
+cjmillsnun That must be the only video of John's that i have not seen. Yes, that sort of thing, but one of my thoughts was about metal enclosures, i remember John doing a video about possible problems when passing AC conductors through steel enclosures. I doubt the load on a typical domestic installation would result in such a problem, and i am sure that units would have knockouts large enough to take both line and neutral tails through the same opening. Plus it would be nice just to hear John's take on the new regulations concerning metal enclosures. Are they really something that is needed from a safety point of view?, if so, why, what are the advantages over say a fire resistant plastic enclosure.
I'm a bit curious about your mains. How much power would you feel comfortable pulling from a typical consumer unit? What is the expected sag under this full loading? I suppose this would only be applicable for things like electric car charging, or tankless electric water heaters where more power is generally preferred. In the US, my typical 200A installation sags around 2.5V per phase, in a 120/240V split phase system, at 48kW loading. Running up to 60kW, it sags ~3V, or 6V total @ 240V. So not that big of a deal to charge a pair of Teslas at 20kW, the typical 123V incoming might drop to 120V.
+Frank Typical UK supply might be 100A x 240V = 24 kW - the same power as a 200A x 120V USA supply? I haven't measured sag (or noticed any visible effect) but I guess the voltage might drop with a couple of electric showers and electric oven all on at the same time.
+redgrittybrick Homes in the US have 'split phase' mains, that gives a center tapped 240V mains, one leg to neutral is 120V, the other leg to neutral is 120V, but from leg to leg is 240V. So things like electric ranges and dryers run on 240V, big air conditioners, electric water heaters... All the normal outlets are 120V, but 240V is available, and the 200A service is 200A on each leg, so for even loading of the legs thats 200A @ 240. My house was built in the 60's and it has 200A service. Newer fancy houses are starting to run 320A or 400A service. Sometimes this has more to do with physical breaker space than it does capacity, and the power company sizes the transformer for the load. So you might have a '400A' residential service with twin 42 space 200A panels, fused at 96kW, but the power company puts you on a shared 50kVa transformer.
Can you give an explanation as of to why my fluke voltage and continuity indicator will trip the RCD. Unless you test between live and neutral first for 5 seconds and then test between live and earth and it will not trip
+journeyonin They are designed that way. The current which flows through the tester is sufficient to trip a 30mA RCD, but connecting it to power first sets it to a low current mode which will not cause the RCD to trip. Newer models have a button to switch between the high and low current modes.
I have one of the c50 boards. I have just found I have 3 double sockets running off a radial circuit which is 2.5mm 30 amp breaker should I change this breaker to a 20amp
totally un related question.if you install a rotary isolator on a on a domestic dwelling on the outside of the building in the garden say would it need to be rcd protected as I'm sure according to regs it has to be a rcd prorected. but what if the owner has a old consumer unit without rcd protection what would you say in this sinario as a replacement board would be an expensive change for the sake of a additional circuit.
+Nicholas Burton An isolator does not require an RCD. The thing it is isolating may require an RCD, and the cables to/from it might depending on how they are installed.
+A. Samrout The requirement (from BS7671 2008 Amd 3) in a nutshell is as of 1/1/16 all consumer units for domestic premises should be made of non combustible material or be installed in a non combustible enclosure. This is only in Britain and it is a compliance issue with a British Standard as opposed to a law. Complying with BS7671 can be used to aid in showing compliance with a law but you can't be prosecuted for not complying with a it, you can be prosecuted for not complying with a statutory law such as the building regs.
You don't need to go through every switch and socket if it trips, all you need to do is to go through MCB 1-6 to isolate the general fault then take it from there. Heaven forbid someone has written on the label with scribble pencil! Cut there hands off for not using the correct sticker provided and immediately throw the consumer unit in the bin, it is absolutely ruined!
Richard Graham - slight problem with your plan. The MCBs don’t isolate the neutral. So if the voltage on the neutral is high enough to still cause 30mA or more to flow to earth, either directly or via a load to the line (live) side of a circuit, the RCD will not be able to be reset, or will immediately trip again.
Or you could just switch off all the breakers, reset the RCD, and switch the breakers on one by one until you have found your fault. Then just leave that one down. Personally, I think regulating for multiple RCDs in a single family home is overkill. How many earth faults will the typical person ever encounter in their lifetime in a typical house? I do not see how this improves safety and it should be left up to the electrician and home owner to decide how many RCDs they want. I have always suspected industry interests behind that change in regulations.
Take off your tin foil hat, the big scary electrical companies aren't out to get you. Also, turning on one by one won't always work as they are only single pole breakers
+Daniel Brydon Well, wouldn't it be money better spent to invest in double pole breakers? I'm not suspecting the electrical companies here, why would I, but if you think manufacturers never influence regulatory change you are pretty naive. Who do you think pays all those lobbyists in Brussels, Greenpeace?
That doesn't help much if you have a neutral to earth fault on one circuit, as the mcb will disconnect the line conductor only, you will never be able to reset the RCD without disconnecting inside the board
I know this is an old thread, but the power to the entire building going out due to a leakage fault (which, altho a fault, CAN and DO occur due to spurious reasons) is a potential safety issue. Imagine a kitchen... maybe an electric kettle in use .... the person takes the kettle off its base, and spills some water. Pop. All the power goes out, INCLUDING the lights. Now a person is stood holding a kettle of boiling water, in the dark. Individual rcbos are getting cheaper, and it's simply a case of it's a LOT more convenient to the customer/consumer. The only thing that's missing on most, that I'd like to see, is some indication WHAT side of the breaker tripped, (overcurrent vs residual current). It'd narrow it down for the people trying to find the fault at 10pm on a sunday ;)
@@dg2908 The RCD measures current imbalance between Live and N. If you isolate every MCB, there is no longer any current flow through the circuits even if a N-E fault is causing the issue. Only when you energise the circuit via the mcb will current flow, tripping the RCD. Twice I have seen people commenting that single pole isolation via mcb won't stop tripping without explaining where the source current is for the N-E faults with all mcbs isolated. In simple terms an RCD is a comparator looking at current flow in two conductors, line and neutral, it cannot compare with line isolated, there is zero current to compare.
Boards should be made to accommodate each MCB module as a double pole, clip in, with remote terminations for both live and neutral. That way whether fitting an RCBO, or MCB< or swapping, the fixed terminations never need touched.
@@jwflame Thanks, haven't seen that...although looking at it their catalogue, the MCB's still seem single pole with a separate neutral bar for those terminations. Would be nice to have no actual wire terminations at the protective device. They would all be remote, and then any MCB, RCBO etc would be a plug in operation or swap etc.
Dear John,
i know this video is a few years old but having come across this board for the first time this week your presentation was a god send. I could not for the life of my locate the current rating on these old MCB's until I watched your programme - great work again.
Thanks
Robert - semi-retired but still plodding along.
I really like your down to earth honesty about what's rubbish and what's still usable. or what's old but good and well made great channel ☺
Square D was bought out by "Schneider Electric" a few years ago... Square D is popular here in Canada and the "QO" series is by far one of the top breakers around... From what I see, those "QO-E" ( European version I assume?) would interchange with what we have here, and vice-versa..
In later years you could get RCD/CB's for the Crabtree C50 boards. Each one would take up the room of two standard breakers and were fitted in exactly the same way.
Crabtree polestar are the same way... two positions but only one is used for feeding power. Is the C50 style also 'split' into two seperate breaker levers so you can tell whether the fault was overcurrent or earth fault?
Fitted one (new old stock, lol) this morning to provide RCD protection on socket circuits on an installation dating from the late 80s or early 90s
Why not replace the whole thing?
My works factory have the C50's DB's everywhere, the original QA stickers are still visible on the side of them and have written 'checked april 68!'
I have installed a few of the Crabtree CUs when I first started back in the late eighties, and no torque screwdriver required , that thing make the modern crap we’ve got now look silly in terns of quality, theses days it all about safety over quality.
I love all this old fashioned stuff.
Brilliant video JW as always 👍👍
The offshore gas production platform I work on in the North Sea has lots of these Square D boards. All three phase and from my opinion very well built. They have been in use since the early 90's with very few issues. We can still get replacements via the company that took them over however they are quite expensive. In-fact we also have RCBO's from the original install in these and they are type 'A' which in the UK we are now only just now getting up to speed with. I assume they would have been supplied from the States who I believe adopted this tech far earlier than we did in the U.K.
America and Canada seem to love Square D. When there no where near as safe as anything in England.
Here in South Africa we went from fuses ( still legal as grandfathered in for when the house was built) to clip in Fuchs and Heinemann ( later Hymag) thermal and magnetic breakers. Only thing you have to do on change of ownership or any upgrade ( replace like for like is not an upgrade, but changing out a 5A round pin socket to a 15A socket still on the existing 2.5mm DCC wire (scary) is classed as an upgrade) requires the upgraded section to comply with the current regulations, so you might find a house with a fuse box with replaceable wire fuses ( often with 2.5mm copper wire as fuse element as that does not blow) and then for the new section you will have next to it a surface mounted box with RCD and breakers, all next to the big wooden panel in the kitchen that holds the electricity meter, with the old cotton covered wiring leading up into the roof space where it runs along to the eave and goes out the side in a pitch filled pipe to the 3 wire overhead line to a street pole. Ground is a 6mm bare wire run next to these, and an additional 6mm wire to a galvanised cold water pipe or to an earth rod outside the kitchen door. The fitting of a RCD and an accessible non hidden mains switch is mandatory on change of ownership however on all houses, so there might be a tiny 4 way box with a RCD only in it and a label on the kitchen wall, the rest being inside a kitchen cupboard and most commonly right above the stove.
There have even been some homeowners who saved cost by only replacing the live wire in the conduit with PVC so the RCD will not trip, leaving the old neutral as DCC and the conduit providing the ground connection. May pass insulation test ( as that typically only looks at the line side and not the neutral) but not a good thing.
Still got loads of the C50's and Polestars at my work, if you drop a spare 3 pole c50 mcb on the floor, it almost certainly leaves a dent lol.
Crabtree c50 there is thousands of them still in use in London underground 💥👍🏻
No fucking way.
If they are not compliant any more, they should be replaced with the latest model.
@ John Ward,
It's strange how the design of them switchboards, almost seems to mimic the later DIN Rail technology.
I've worked on the NZ equivalent of the Crabtree, as in Gael switchboards, they were made more for Industrial and Commercial installations.
With the circuit-breakers you were showing, was there an option to inter-link 3 circuit-breakers on a given circuit?
I do know that there was a captive link you could get for the Gael circuit-breakers.
I don't miss the live exposed busbars though, especially when there were 3 of them.
Thanks for the great video.
Those Square-D breakers do quite resemble US-style.
Thjey look like the Quick-Lag breakers
One day you have to play that keyboard for us. Deal?
Hey John, could you explain your view on why you always refer to the live phase as a "Line" connection, versus the commonly (and I assume incorrectly) used term "Live". My guess at what's behind your thinking here is that even Neutral or Earth connections are still effectively and potentially "Live" (as in phase hot) connections in an active circuit, and so should always be considered as being "Live", versus "Line" being specifically the phase supply of a circuit as differentiated from a Neutral or Earth connection.
Am I on the mark here?
+9ff70f96 Yes, it was redefined fairly recently so that the conductors are line & neutral, with 'live' referring to any conductor that carries current in normal operation, so live includes both line and neutral.
+John Ward - Thank you for the response.
Good video John thanks,is that the M100 hammond valve organ?
Just a quick question, do you know the current rating of the main switch in the Crabtree C50 distribution board you had? I had to inspect a property yesterday with that exact 6 way DB in it.
Hi John I seem to remember that the regulations stated that heavy load should be at the main switch. As the shower circuit breaker has been added at a later time perhaps more thought into where the breaker should be placed.
I think that's a bit of a myth. The busbar should be able to handle the full load current at the far end. But it's a practice so common as to be considered 'rules' to put the larger breakers to the feed end
(and imnsho, a good practice)
@ Edwin Waugh,
No, it is Kirchoffs 2nd (or 3rd) Law of current distribution that means it should have been put there. :)
John, do you still have the Square D CU?
As others have noted, it bears striking similarity to the "QO" line marketed in the US market. If you've still got it, and would be willing, I'd like to ship you a few breakers to see if they really are compatible, or if Schneider/SqD altered some spacing to prevent them from fitting...
Here in the United States we have square d type homeline circuit breakers.
Crabtree C50 breakers bomb proof, quality sadly lacking today.
If the PSCC hadn't increased, these things would still be OK, but that is progress.
The last time I saw one of those Qwikline boards with the clip on breakers was in a house built c.1990, surely much newer than the C50
+David Gill The C50 board in the video is probably 1970s, but C50 MCBs and boards were still being manufactured up to 2006/2007.
+John Ward I've never seen a C50 in a domestic installation but I guess that's because it would have cost more than a 3036 Wylex... The C50's 3kA breaking capacity is well specc'd in comparison. Do the C50 breakers say what trip curve they are?
+David Gill BS 3871 Type 2 until approximately 1992, then BS EN 60898 Type C.
Our house has a c50 consumer unit
Our house has a c50 consumer unit
Picked up some old switches from a rewire this week.... don't know if I can send a pic to see if u can date them and also would they still comply to be e refitted
Nice. I had a little problem with the accent but a great video. An American in the house.
Would love to see you do a video/s on emergency lighting kind of like your heater series. but I am selfish in my requests.
Nice video, John. Now you need to do a similar video on a new compliant unit, explaining the pro's and con's.
+100SteveB Are you suggesting that these are not compliant?
impactvision
Not compliant to fit today.
+cjmillsnun That must be the only video of John's that i have not seen. Yes, that sort of thing, but one of my thoughts was about metal enclosures, i remember John doing a video about possible problems when passing AC conductors through steel enclosures. I doubt the load on a typical domestic installation would result in such a problem, and i am sure that units would have knockouts large enough to take both line and neutral tails through the same opening. Plus it would be nice just to hear John's take on the new regulations concerning metal enclosures. Are they really something that is needed from a safety point of view?, if so, why, what are the advantages over say a fire resistant plastic enclosure.
I'm a bit curious about your mains. How much power would you feel comfortable pulling from a typical consumer unit? What is the expected sag under this full loading? I suppose this would only be applicable for things like electric car charging, or tankless electric water heaters where more power is generally preferred. In the US, my typical 200A installation sags around 2.5V per phase, in a 120/240V split phase system, at 48kW loading. Running up to 60kW, it sags ~3V, or 6V total @ 240V. So not that big of a deal to charge a pair of Teslas at 20kW, the typical 123V incoming might drop to 120V.
+Frank i have a 50a connection for a 3 bed 1960's house, 200a is huge!
+Frank Typical UK supply might be 100A x 240V = 24 kW - the same power as a 200A x 120V USA supply? I haven't measured sag (or noticed any visible effect) but I guess the voltage might drop with a couple of electric showers and electric oven all on at the same time.
+redgrittybrick Homes in the US have 'split phase' mains, that gives a center tapped 240V mains, one leg to neutral is 120V, the other leg to neutral is 120V, but from leg to leg is 240V. So things like electric ranges and dryers run on 240V, big air conditioners, electric water heaters... All the normal outlets are 120V, but 240V is available, and the 200A service is 200A on each leg, so for even loading of the legs thats 200A @ 240. My house was built in the 60's and it has 200A service. Newer fancy houses are starting to run 320A or 400A service. Sometimes this has more to do with physical breaker space than it does capacity, and the power company sizes the transformer for the load. So you might have a '400A' residential service with twin 42 space 200A panels, fused at 96kW, but the power company puts you on a shared 50kVa transformer.
@frank. One word (lol) AirConditioning :)
Can you give an explanation as of to why my fluke voltage and continuity indicator will trip the RCD. Unless you test between live and neutral first for 5 seconds and then test between live and earth and it will not trip
+journeyonin They are designed that way. The current which flows through the tester is sufficient to trip a 30mA RCD, but connecting it to power first sets it to a low current mode which will not cause the RCD to trip.
Newer models have a button to switch between the high and low current modes.
Is Bakelite hard brittle plastic?
ill have crabbtree dist boargs on site. Looking for blanking plates
I have one of the c50 boards. I have just found I have 3 double sockets running off a radial circuit which is 2.5mm 30 amp breaker should I change this breaker to a 20amp
Yes, 2.5mm² cable is only rated to about 26A maximum. C50 breakers are still available on ebay and similar places.
Ok cheers
The c50 widow maker series 👍
totally un related question.if you install a rotary isolator on a on a domestic dwelling on the outside of the building in the garden say would it need to be rcd protected as I'm sure according to regs it has to be a rcd prorected. but what if the owner has a old consumer unit without rcd protection what would you say in this sinario as a replacement board would be an expensive change for the sake of a additional circuit.
+Nicholas Burton An isolator does not require an RCD.
The thing it is isolating may require an RCD, and the cables to/from it might depending on how they are installed.
+Nicholas Burton - You could just install a standalone RCD unit near the old non-RCD CU.
I like square d circuit breakers?
Why are plastic consumer boards outlawed?
The plastic CUs were believed to be a fire risk.
+royhills Interesting. Does this apply to sub distribution boards within an apartment etc?
+A. Samrout
The requirement (from BS7671 2008 Amd 3) in a nutshell is as of 1/1/16 all consumer units for domestic premises should be made of non combustible material or be installed in a non combustible enclosure. This is only in Britain and it is a compliance issue with a British Standard as opposed to a law.
Complying with BS7671 can be used to aid in showing compliance with a law but you can't be prosecuted for not complying with a it, you can be prosecuted for not complying with a statutory law such as the building regs.
+A. Samrout Applies to ALL consumer units, but not general enclosures or adaptable boxes
Thanks for all the replies. I bet it won't be long until we follow suit here in Oz. A good ruling I think.
Why can't you apply a high voltage insulation test?
Why would you?
You don't need to go through every switch and socket if it trips, all you need to do is to go through MCB 1-6 to isolate the general fault then take it from there. Heaven forbid someone has written on the label with scribble pencil! Cut there hands off for not using the correct sticker provided and immediately throw the consumer unit in the bin, it is absolutely ruined!
Richard Graham - slight problem with your plan. The MCBs don’t isolate the neutral. So if the voltage on the neutral is high enough to still cause 30mA or more to flow to earth, either directly or via a load to the line (live) side of a circuit, the RCD will not be able to be reset, or will immediately trip again.
Or you could just switch off all the breakers, reset the RCD, and switch the breakers on one by one until you have found your fault. Then just leave that one down.
Personally, I think regulating for multiple RCDs in a single family home is overkill. How many earth faults will the typical person ever encounter in their lifetime in a typical house? I do not see how this improves safety and it should be left up to the electrician and home owner to decide how many RCDs they want. I have always suspected industry interests behind that change in regulations.
Take off your tin foil hat, the big scary electrical companies aren't out to get you. Also, turning on one by one won't always work as they are only single pole breakers
+Daniel Brydon Well, wouldn't it be money better spent to invest in double pole breakers? I'm not suspecting the electrical companies here, why would I, but if you think manufacturers never influence regulatory change you are pretty naive. Who do you think pays all those lobbyists in Brussels, Greenpeace?
That doesn't help much if you have a neutral to earth fault on one circuit, as the mcb will disconnect the line conductor only, you will never be able to reset the RCD without disconnecting inside the board
I know this is an old thread, but the power to the entire building going out due to a leakage fault (which, altho a fault, CAN and DO occur due to spurious reasons) is a potential safety issue.
Imagine a kitchen... maybe an electric kettle in use .... the person takes the kettle off its base, and spills some water. Pop. All the power goes out, INCLUDING the lights. Now a person is stood holding a kettle of boiling water, in the dark.
Individual rcbos are getting cheaper, and it's simply a case of it's a LOT more convenient to the customer/consumer.
The only thing that's missing on most, that I'd like to see, is some indication WHAT side of the breaker tripped, (overcurrent vs residual current). It'd narrow it down for the people trying to find the fault at 10pm on a sunday ;)
@@dg2908 The RCD measures current imbalance between Live and N. If you isolate every MCB, there is no longer any current flow through the circuits even if a N-E fault is causing the issue. Only when you energise the circuit via the mcb will current flow, tripping the RCD. Twice I have seen people commenting that single pole isolation via mcb won't stop tripping without explaining where the source current is for the N-E faults with all mcbs isolated. In simple terms an RCD is a comparator looking at current flow in two conductors, line and neutral, it cannot compare with line isolated, there is zero current to compare.
Like
what is the point of this video
I laughed at your question
Boards should be made to accommodate each MCB module as a double pole, clip in, with remote terminations for both live and neutral. That way whether fitting an RCBO, or MCB< or swapping, the fixed terminations never need touched.
Already available, Schneider Acti9 Isobar P.
@@jwflame Thanks, haven't seen that...although looking at it their catalogue, the MCB's still seem single pole with a separate neutral bar for those terminations. Would be nice to have no actual wire terminations at the protective device. They would all be remote, and then any MCB, RCBO etc would be a plug in operation or swap etc.