Replacing an old CU with a new one

[Naz1977]

I never mentioned anything about idiots and I don't think that's appropriate language for the forums. Please be constructive.

Therefore your installation is potentially dangerous and should be turned off until it's made safe.

The idiots I was referring to , are the 2 electricians that came and visited my property and no one on this forum

I am sorry, but if an installation is unsafe, they should make this clear immediately. The last one, didn't want to replace the CU, didn't want to do any work, and then said my earth to the spike was too thin at 6mm and needed 10mm even though it is not buried in the ground!

I might turn off the power from the isolator I have at the moment and replace the CU with the one I have. I then worry about the tail upgrade later on as currently the tails at 16mm will be more than ok for my current setup.

Thanks for the heads up.

 

[securespark]

The fundamental principle of eebads

Not having a go, but it is now ADS (Automatic Disconnection of Supply).

 

[Naz1977]

potatoe potato

Same thing

I understand the principle. Previously all sockets were plastic and didn't matter. But as I have been replacing them with metal one, that obviously matters and tbh it did slip my mind.

But other metal units, like fridge, boiler and ... are ok as they are connected to the new ring main which is protected by RCBO

I will replace the CU as a matter of priority

 

[John D v2.0]

The idiots I was referring to , are the 2 electricians that came and visited my property and no one on this forum

I am sorry, but if an installation is unsafe, they should make this clear immediately. The last one, didn't want to replace the CU, didn't want to do any work, and then said my earth to the spike was too thin at 6mm and needed 10mm even though it is not buried in the ground!

I might turn off the power from the isolator I have at the moment and replace the CU with the one I have. I then worry about the tail upgrade later on as currently the tails at 16mm will be more than ok for my current setup.

Thanks for the heads up.

OK so how are you going to check your r1+r2 for each circuit? And how will you check your disconnection times? How do you know your polarity is correct everywhere? Will you do ir testing on your circuits?

Don't get me wrong, it's perfectly possible to change your cu without the proper qualifications, but calling some sparkys idiots and then doing it yourself sound like false confidence. If you're doing anything yourself, know that you're doing it to the letter. Know all the tests and why they are important. If you can't explain each test and what happens if it's not done, then don't do the work.n my hint is that if any of the tests wouldn't pass, then you're likely to have either an immediately dangerous or a potentially dangerous situation.

 

[John D v2.0]

I understand the principle. Previously all sockets were plastic and didn't matter.

it would be funny if you weren't being serious

 

[Naz1977]

I am pretty sure I don't have an immediately dangerous setup as I haven't been killed yet

What I am gonna do, is to replace it to give me the better protection in terms of the RCD.

Then I will get someone else to come and do another EICR for me on the setup. They should then do the full testing of the installation to say if it is safe or not?

As for disconnection times, it is really a given isn't it if an RCD is used? Specially in a TT circuit where it can't be properly tested. I seem to remember reading somewhere the disconnection time can't really be measured and with modern RCDs it is a given?

 

[John D v2.0]

Not having a go, but it is now ADS (Automatic Disconnection of Supply).

I understand the principle but not the terminology. Seems our op is just grandma humming along to the tune with completely the wrong words

 

[John D v2.0]

I am pretty sure I don't have an immediately dangerous setup as I haven't been killed yet

What I am gonna do, is to replace it to give me the better protection in terms of the RCD.

Then I will get someone else to come and do another EICR for me on the setup. They should then do the full testing of the installation to say if it is safe or not?

As for disconnection times, it is really a given isn't it if an RCD is used? Specially in a TT circuit where it can't be properly tested. I seem to remember reading somewhere the disconnection time can't really be measured and with modern RCDs it is a given?

Wrong, furthermore you're making me look knowledgeable with your random incorrect assertions

 

[securespark]

I am pretty sure I don't have an immediately dangerous setup as I haven't been killed yet

Just because you're still with us does NOT mean your installation is safe!

Your VO ELCB appears to have no earth connection, in which case it is effectively useless.

Does it trip when you press the yellow button?

Regardless, they were deleted from the regulations in 1985 as there could still be a shock risk even with one installed.

If you have RCD protecting a circuit it should give protection on a TT supply.

But, you have not got RCD protection for all your circuits and they have not been tested.

Please don't be lax about this. Get an EICR ASAP and act on its recommendations.

 

[flameport]

As for disconnection times, it is really a given isn't it if an RCD is used?

Only if the RCD is the correct type and is working. They can go faulty. Or even be faulty out of the box. They can also trip when the test button is pressed, but not when a fault occurs. Or take far too long to trip, trip at the wrong current, only trip in certain circumstances or set on fire when the test button is pressed. The possibilities are endless.

However as most of your circuits haven't got one, nothing will trip. The earth electrode will sizzle in the ground as the wires in the walls heat up and all of the metal cased items such as your kettle and washing machine continuously deliver lethal electric shocks to anyone who touches them.

Specially in a TT circuit where it can't be properly tested.

A TT system can be and is tested just like any other.

 

[flameport]

 

[Naz1977]

Only if the RCD is the correct type and is working. They can go faulty. Or even be faulty out of the box. They can also trip when the test button is pressed, but not when a fault occurs. Or take far too long to trip, trip at the wrong current, only trip in certain circumstances or set on fire when the test button is pressed. The possibilities are endless.

However as most of your circuits haven't got one, nothing will trip. The earth electrode will sizzle in the ground as the wires in the walls heat up and all of the metal cased items such as your kettle and washing machine continuously deliver lethal electric shocks to anyone who touches them.


A TT system can be and is tested just like any other.

The chances of any of the above happening on a brand new unit, is no more than the chance of getting it fitted by a leccy and then the following day the RCD fails and catches fire and ...

I completely understand what you are saying and I do understand that the current setup can be dangerous if certain fault condition occur and ...

Which is why I will be looking to replacing the CU as soon as possible and get it then tested to make sure it is safe.

 

[John D v2.0]

You keep saying you understand but illustrating that you don't

 

[phatboy]

You are a dangerous fool.

Stop pretending you understand, the only person you are fooling is yourself.

 

[flameport]

I will be looking to replacing the CU as soon as possible and get it then tested to make sure it is safe.

Wrong way - testing (and any required repairs) first, replacement CU afterwards.

Before that, as an absolute minimum the old VOELCB should be removed and a 100mA RCD installed in it's place. That isn't technically compliant but will ensure that power is disconnected in the event of a fault.