No RCD = EICR fail ?

SusieT

Could I please jump on this thread with a question? I am going back to look at an old farm house, and I am sure it had only blocks as in this post https://forums.moneysavingexpert.com/discussion/comment/79862636/#Comment_79862636
I can see from another post that the RCD blocks have a trip function and it looks as if there is a little button that you press in when it is tripped, but do those non RCD blocks trip, or are they only on off switches and the main switch would be the one to trip if something happened?
If for simplicity it has 5 switches for up and downstairs lights + sockets + oven I take it if the wiring were otherwise good, all that would be needed would be to swap to RCD's?
I would add that if I do go further with the other house I will get an electrician in to check the electrics, but would like to have a good idea of what I am looking at first.

grumbler

SusieT said:

Could I please jump on this thread with a question? I am going back to look at an old farm house, and I am sure it had only blocks as in this post https://forums.moneysavingexpert.com/discussion/comment/79862636/#Comment_79862636

What do you call 'blocks'?  'Switches' in the consumer units - MCBs?

I can see from another post that the RCD blocks have a trip function and it looks as if there is a little button that you press in when it is tripped,

This button is for testing.

but do those non RCD blocks trip, or are they only on off switches and the main switch would be the one to trip if something happened?

MCB trips from overloading - high current.

RCD trips when current leaks to earth, even very small.

If for simplicity it has 5 switches for up and downstairs lights + sockets + oven I take it if the wiring were otherwise good, all that would be needed would be to swap to RCD's?

One RCD and several MCBs work together and provide different types of protection, you cannot 'swap' them.

There are RCBOs (see the link above in the thread) that combine two types in one.

SusieT

grumbler said:

SusieT said:

Could I please jump on this thread with a question? I am going back to look at an old farm house, and I am sure it had only blocks as in this post https://forums.moneysavingexpert.com/discussion/comment/79862636/#Comment_79862636

What do you call 'blocks'?  'Switches' in the consumer units - MCBs?

I can see from another post that the RCD blocks have a trip function and it looks as if there is a little button that you press in when it is tripped,

This button is for testing.

but do those non RCD blocks trip, or are they only on off switches and the main switch would be the one to trip if something happened?

MCB trips from overloading - high current.

RCD trips when current leaks to earth, even very small.

If for simplicity it has 5 switches for up and downstairs lights + sockets + oven I take it if the wiring were otherwise good, all that would be needed would be to swap to RCD's?

One RCD and several MCBs work together and provide different types of protection, you cannot 'swap' them.

There are RCBOs (see the link above in the thread) that combine two types in one.

It is MCB's I think I saw, so if they have an overload they will trip but if an appliance that has a problem it will trip the main switch, but an RCD would only trip its circuit and if I was stupid enough to somehow stick my finger in a live wire it should save me from a shock? 
I will have a closer look, and then get an electrician to have a look if/when I go further. Thank you very much.

Nearlyold

The button on an RCD is for testing,  it simulates an earth fault.

The other switches you refer to are miniature circuit breakers referred to as MCBs. They protect against over current and will trip in the event of a short circuit for example (which might otherwise cause a fire). You can indeed turn them off manually to isolate a specific circuit. 

You can't replace all the  MCBs with RCDs as they protect against different hazards. 

The usual method is to have each bank of MCBs covered by an RCD so a Consumer Unit with two banks of MCBs would have two RCDs

RCBOs are available which offer both over current and earth fault protection in the one device.

SusieT

Nearlyold said:

The button on an RCD is for testing,  it simulates an earth fault.

The other switches you refer to are miniature circuit breakers referred to as MCBs. They protect against over current and will trip in the event of a short circuit for example (which might otherwise cause a fire). You can indeed turn them off manually to isolate a specific circuit. 

You can't replace all the  MCBs with RCDs as they protect against different hazards. 

RCBOs are available which offer both over current and earth fault protection in the one device.

Thank you, that is perfect, should sink into my head easily

Section62

SusieT said:

...but an RCD would only trip its circuit and if I was stupid enough to somehow stick my finger in a live wire it should save me from a shock? 

An RCD working correctly should help reduce the risk of you receiving a fatal electric shock in some situations, but it shouldn't be relied on as a method of preventing electric shock because there is no guarantee it will work, or you might be unlucky and find yourself in one of the situations where an RCD won't trip even though it is working as designed.

SusieT

Section62 said:

SusieT said:

...but an RCD would only trip its circuit and if I was stupid enough to somehow stick my finger in a live wire it should save me from a shock? 

An RCD working correctly should help reduce the risk of you receiving a fatal electric shock in some situations, but it shouldn't be relied on as a method of preventing electric shock because there is no guarantee it will work, or you might be unlucky and find yourself in one of the situations where an RCD won't trip even though it is working as designed.

Thank you, hopefully I willnever be in that position, I am very respectful of electricity, some very simple things I am happy to but only if it is off at the mains! At least from reading here I know its a good idea to get one or more fitted though, so will also have a look at whats in this house as well.

Risteard

Section62 said:

SusieT said:

...but an RCD would only trip its circuit and if I was stupid enough to somehow stick my finger in a live wire it should save me from a shock? 

An RCD working correctly should help reduce the risk of you receiving a fatal electric shock in some situations, but it shouldn't be relied on as a method of preventing electric shock because there is no guarantee it will work, or you might be unlucky and find yourself in one of the situations where an RCD won't trip even though it is working as designed.

Or it will trip but you'll still be a corpse.

movilogo

So coming back to my question, this is a rough sketch of how I have 2 consumer units (or fuse boxes). So the question is, if I make CU1 as RCD complaint, will that be compliant for CU2 as well? If I set the trip switch marked Kitchen in CU1, no power goes to CU2.

grumbler

Well, the sketch makes very little sense. I guess the second CU is operated by the 'kitchen' MCB, not connected directly to 'AC'.

Not sure about the formalities, but if in the CU1 some MCBs, including the 'kitchen' one, are connected to 'AC' via an RCD, then all these circuits will be protected, including the CU2.