RCBOs

[hard-work]

The great thing about having all RCBOs, is that the fault is isolated to only one circuit. The circuits that are fault free stay operational.

 

[EFLImpudence]

Faulse economy. Installing all CUs with RCBO is not a great amount of money.

Nevertheless, that is how most customers think.

 

[hard-work]

Electrical installations are a compromise.

With all RCBOs the compromise is vastly reduced. Then with DP RCBOs the compromise is vastly reduced again. RCBOs are not a great expense, for what they offer. It is a no-brainer.

 

[hard-work]

Nevertheless, that is how most customers think.

Safety is last on the list after economy.

 

[EFLImpudence]

With all RCBOs the compromise is vastly reduced. Then with DP RCBOs the compromise is vastly reduced again. RCBOs are not a great expense, for what they offer. It is a no-brainer.

Yet Bernard has given an example where it would be beneficial not to do it.

How many millions of RCDs have been installed?
How many fewer casualties are there now than before?

 

[hard-work]

Be logical. A bank of circuits of an RCD can be tripped out, and take out the boiler and freezer in mid-winter. All because of a small fault on a circuit unrelated to your boiler and freezer. It is not difficult to figure this out.

 

[hard-work]

How many millions of RCDs have been installed?
How many fewer casualties are there now than before?

If your young daughter was electrocuted because someone wanted to save a few quid, you might think differently.

 

[stillp]

What if your young daughter was electrocuted because somebody thought an RCD would protect her?

 

[hard-work]

What if your young daughter was electrocuted because somebody thought an RCD would protect her?

There is a greater chance of being protected via an RCD or RCBO than not having them. Pretty obvious really.

 

[Iggifer]

There is a greater chance of being protected via an RCD or RCBO than not having them. Pretty obvious really.

His point is an RCD is not the one and only solution for protection against electric shocks. They MAY stop you getting a fatal/harmful shock, but they also may not. A well designed, well installed and maintained installation is far more important than an RCD.

There is a reason they're not required on every circuit on every installation

 

[JohnW2]

There is a greater chance of being protected via an RCD or RCBO than not having them. Pretty obvious really.

We've been through this umpteen times before.

What you say is, indeed, literally 'obvious' but the question is whether the billions that have probably been spent on buying and installing RCDs/RCBOs has actually resulted in any noticeable reduction in deaths or serious injuries due to electric shock, whereas had the money been spent on other things (like road safety), that might well have resulted in more reduction in deaths/injuries.

Do you know, or have you heard of, anyone who has suffered (and survived) an electric shock which caused an RCD or RCBO to trip - since they are the people who might have died or suffered serious injury in the absence of the RCD/RCBO?? Whenever the question has been asked in this forum, few, if any, of those who have responded have ever come across such a case.

Kind Regards, John

 

[JohnW2]

The problem with all-RCD boards is that you don't know if a trip was caused by overcurrent or earth leakage (or even spikes on the supply).

I presume you mean "all-RCBO", in which case I agree with you.

I think that some of the ludicrously expensive devices do it, but I wouldn't have thought that it would be particularly difficult or expensive for all RCBOs to provide an indication oof what had caused a trip.

Kind Regards, John

 

[stillp]

An RCBO, or other RCD, will not prevent you getting a shock. It might prevent a shock from being fatal.

 

[John D v2.0]

Thanks Bernard. A double pole RCBO in all slots on a CU is the ultimate then.

Ultimate what? Surely a massive Henley block with swa to every light/socket and individual rcd and fuse would be the ultimate? And no metallic services eg gas incomer. Etc.

 

[JohnW2]

An RCBO, or other RCD, will not prevent you getting a shock. It might prevent a shock from being fatal.

You presumably are referring to the situation in which a substantial potential difference arises been two parts of a human body, in which case I agree with you. One might add a comment about the commonly-held misconception that an RCD/RCBO will limit the shock current to 30mA or whatever, which obviously is not the case - such as device will, if it operates, limit the duration of the shock, but not the amount of current flowing through the person during that brief period of time.

However, in a more general sense it can be argued that RCDs/RCBOs can 'prevent one getting a shock' - if a 'leakage' large enough to trip an RCD but not large enough to trip an OPD (fuse, MCB or whatever) results in something touchable becoming 'live'. In that situation an RCD will hopefully clear the fault before anyone has a chance to touch the live object and get a shock. However, that's a possible argument for have some sort of RCD protection, not necessarily an RCBO.

Kind Regards, John