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Does a SPD need a dedicated MCB?

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oscar21

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Does a SPD need a dedicated way?

I need an extra way in this unit for a 3 phase car charger

IMG_20240503_132821_535.jpg


As you can see its a small unit with no extra ways, the building is rented and the tenant is adamant that the board is not to be changed as he has been told no major alterations. We have already bodged it somewhat on his say so by adding a small single phase board for some extra lighting and sockets he wanted (we shuffled the circuits about so all the socket/water heater circuits were spread across the phases and its just lighting sat on the single phase board, thats was last year and everything has been fine so far. I would have fitted an aditional 3ph unit but the mains cupboard is tiny.

He now wants to do similar with the car charger but I need three ways so it would mean moving three socket circuits all onto one phase. But I was thinking, the little unit below has the SPD in it which is fed from a 32A 3 phase MCB, any reason the car charger can't share the same MCB from a regs point of view?

I know its a bodge but I'll be bodging it anyway in one way or another, I also cant say no as its the bloke's office that gives us tonnes of work.

Now for the second question, I don't normally fit car chargers, this is the unit he's bought,


Cant make head nor tail of the instructions, they have a whole paragraph dedicated to how the lead might strangle a kid but nothing that I can find on the type of connection, rating etc, main question is will it need an RCD, the supply cable wont need it as its back to back with the mains unit.

I hate getting involved in stuff like this, its always far from straightforward.
 
it does sound utterly complicated though
It actually isn't if you follow a logical process through the design and install process. You can then make informed choices to make the install easier.
If an electrician cant fit a simple car charger
I wouldn't call a 3 phase unit simple
Lets be honest its no harder to connect up than the roller shutter we did last year for him.
But arguably significantly more dangerous if it isn't done right.
With your current philosophy of disinterest in anything you don't know or won't research I don't think you will attract much help.
 
You can clearly see this when a site manager slopes off for the day and everyone is left to their own devices, the site always runs so much better.

I guess much depends on the sort of site you're referring to. Anywhere I work the site manager is first in and last out. At a lower level I could say a lot about our contracts manager, but most of it would be based on ignorance as I've no idea what he does for most of the day. What I do know is he's often heading onto sites as I'm leaving, to start measuring up for pricing of extras.

As for regulations? Well I don't see them as a pick and choose sort of deal. You signed up for this, so it might be an idea to suck it up or look for something with a lighter regulatory touch like joinery or painting & decorating.

Perhaps I seem a touch harsh, but I don't think so. I've knocked my pan in earning much less than I could to get into this trade the hard way and it's not impressive to read comments from someone who likes to wear the 'electrician' badge while behaving like a rank amateur.

EV charge points aren't difficult. Sure there's some additional learning involved, and for good reason, but it's not particularly taxing. Perhaps you'll take the time to gain a better understanding or perhaps you won't, but without doing so I don't think it's likely to sink in just how utterly stupid some of your comments have been in this thread.
 
I guess much depends on the sort of site you're referring to. Anywhere I work the site manager is first in and last out. At a lower level I could say a lot about our contracts manager, but most of it would be based on ignorance as I've no idea what he does for most of the day. What I do know is he's often heading onto sites as I'm leaving, to start measuring up for pricing of extras.

As for regulations? Well I don't see them as a pick and choose sort of deal. You signed up for this, so it might be an idea to suck it up or look for something with a lighter regulatory touch like joinery or painting & decorating.

Perhaps I seem a touch harsh, but I don't think so. I've knocked my pan in earning much less than I could to get into this trade the hard way and it's not impressive to read comments from someone who likes to wear the 'electrician' badge while behaving like a rank amateur.

EV charge points aren't difficult. Sure there's some additional learning involved, and for good reason, but it's not particularly taxing. Perhaps you'll take the time to gain a better understanding or perhaps you won't, but without doing so I don't think it's likely to sink in just how utterly stupid some of your comments have been in this thread.
And yet in over 30 years of doing this the amount of cockups I've been called back to still sits at zero, not one loose connection, not one socket wired backwards. Yet virtually every installation I turn up to looks like its been wired by Stevie Wonder.
People will miss my sort when we are retired (not too long now) once they are all tied up in corporate speak, potless and nothing achieved.
 
And yet in over 30 years of doing this the amount of cockups I've been called back to still sits at zero, not one loose connection, not one socket wired backwards. Yet virtually every installation I turn up to looks like its been wired by Stevie Wonder.
People will miss my sort when we are retired (not too long now) once they are all tied up in corporate speak, potless and nothing achieved.

You've completely missed the point.
 
The original question can you pair it with the SPD no, mode 3 chargers need connecting to a dedicated circuit.
Yes I know but I live in the real world. Regs like this were brought about so you didn't piggy back them off something like a socket circuit that was already loaded.

Lets take an immersion circuit, they used to run off a fused spur from the ring without any problem whatsoever, then someone said dedicated circuit only which made sense because all of a sudden socket circuits had more than a wooden lamp plugged into them.

Would I connect an immersion to the ring circuit nowadays? No way. Would I wire a boiler from the same circuit as the new immersion feed I've just wired, absolutely if it saved a second run of 2.5 across the house because the boiler uses such a minuscule amount of power that it wont affect the immersion circuit (that will never be used) one little bit.

The SPD uses zero current, it could probably be connected to the bus bar right on the other side of the MCB without any issue whatsoever, the electrons don't know where its connected so apart from upsetting someone who wrote a vastly overpriced book, in the grand scheme of things, it doesn't really matter.

And that philosophy has been proven the world over by countless millions of people.
 
Yes I know but I live in the real world. Regs like this were brought about so you didn't piggy back them off something like a socket circuit that was already loaded.

Lets take an immersion circuit, they used to run off a fused spur from the ring without any problem whatsoever, then someone said dedicated circuit only which made sense because all of a sudden socket circuits had more than a wooden lamp plugged into them.

Would I connect an immersion to the ring circuit nowadays? No way. Would I wire a boiler from the same circuit as the new immersion feed I've just wired, absolutely if it saved a second run of 2.5 across the house because the boiler uses such a minuscule amount of power that it wont affect the immersion circuit (that will never be used) one little bit.

The SPD uses zero current, it could probably be connected to the bus bar right on the other side of the MCB without any issue whatsoever, the electrons don't know where its connected so apart from upsetting someone who wrote a vastly overpriced book, in the grand scheme of things, it doesn't really matter.

And that philosophy has been proven the world over by countless millions of people.
None of that has any relevance whatsoever. As I said I don't care what you do but you came here and asked. Do what you like and bodge it that is clearly the way you operate because you are ignorant to improving your knowledge.
 
Yes I know but I live in the real world. Regs like this were brought about so you didn't piggy back them off something like a socket circuit that was already loaded.

Lets take an immersion circuit, they used to run off a fused spur from the ring without any problem whatsoever, then someone said dedicated circuit only which made sense because all of a sudden socket circuits had more than a wooden lamp plugged into them.

Would I connect an immersion to the ring circuit nowadays? No way. Would I wire a boiler from the same circuit as the new immersion feed I've just wired, absolutely if it saved a second run of 2.5 across the house because the boiler uses such a minuscule amount of power that it wont affect the immersion circuit (that will never be used) one little bit.

The SPD uses zero current, it could probably be connected to the bus bar right on the other side of the MCB without any issue whatsoever, the electrons don't know where its connected so apart from upsetting someone who wrote a vastly overpriced book, in the grand scheme of things, it doesn't really matter.

And that philosophy has been proven the world over by countless millions of people.
Until the immersion element blows down to earth and you've suddenly got immersion and no boiler either.

Also the immersion would be on a high current MCB the inrush current and high fault current of a earth fault would likely blow the PCBs of the boiler.

Of course it'll work fine but there's a reason we separate loads and design circuits based on the load they carry and separate vulnerable equipment.

Put the SPD on its own breaker as the manufacturer requires in their data sheet. And a 3 phase charger will require more than just a MCB to protect it. The last fast charger I helped to put in had to have a 4 pole breaker that disconnected the earth and an earth cage under the concrete.

But you'll just stick it in with the SPD to save on a new enclosure just below the DB.
 
Until the immersion element blows down to earth and you've suddenly got immersion and no boiler either.

Also the immersion would be on a high current MCB the inrush current and high fault current of a earth fault would likely blow the PCBs of the boiler.

Of course it'll work fine but there's a reason we separate loads and design circuits based on the load they carry and separate vulnerable equipment.

Put the SPD on its own breaker as the manufacturer requires in their data sheet. And a 3 phase charger will require more than just a MCB to protect it. The last fast charger I helped to put in had to have a 4 pole breaker that disconnected the earth and an earth cage under the concrete.

But you'll just stick it in with the SPD to save on a new enclosure just below the DB.
Most of thats rubbish, you must know that. If the immersion blew you would simply switch it off at the DP switch and carry on using the boiler circuit, apart from the fact the immersion is only used if the boiler breaks, not the other way round. As for blowing the PCB fuses, how? you could spur off a socket for a boiler FCU and plug a big heater into the socket, if the heater wen't bang that wouldn't affect the boiler would it.

Secondly how will putting a separate enclosure next to the mains help my situation, its either a complete new board or an additional 3 phase board, splitting the tails and all the work that ensues, it will cost a good few hundred either way and the bloke doesn't want to pay that. As it happens the manufacturer have got back to me and stated it needs RCD protection so I will be fitting a separate enclose for that. They didn't mention earth grids etc. Why would they, what happens if someone doesn't park on it and charges their car?

Normally I'd say I cant do it but he is the best giver of work and payer we've ever had and I'm not putting that at risk by being awkward, especially when the next electrician turns up, bodges it in 5 minutes and says how easy it was. So if the worst that will happen is a few regs fans have a little cry then I'm all for it.
 
If this is for outside charger and it doesn't incorporate open PEN protection you need to put measures in place. Most do now but something from EBay I would be dubious about.
But hey you don't care.
DNO notification is required.
I do care, I don't do dangerous stuff, I just don't do everything anyone tells me to do, if I think a reg is daft or over the top I'll do what I think is right, I use common sense instead of blind faith. The limited instructions I linked to earlier state that it has open PEN protection and ground protection (whatever that is) you have to go into the display settings to turn it on apparently.
 
What I do find baffling though is this is meant to be the future, the government want everyone in little electric euro boxes but if I was doing a similar job to this for an independent customer I'd want about £2-3K to even think about getting involved, its not a line of work I would like to get into at all, far too many hoops to jump though.

There must be a fair few others that think like me as well which can only cause problems for the end user, they will want an easy life and just end up buying another diesel. .
 

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