Joys of "Park" homes - Can an RCD be described as "Earth Leakage Circuit Breaker" ?

[timhoward]

Regarding point 2 - that is your choice and not the only way to do it.
An up front / time delayed RCD is not needed if every circuit has RCBO protection as this provides the fault protection.
Things evolve and a metal CU with a tails clamp is deemed to be safe enough these days, making tail faults upstream of the CU’s protective devices extremely unlikely.

 

[Robert2254]

Regarding point 2 - that is your choice and not the only way to do it.
An up front / time delayed RCD is not needed if every circuit has RCBO protection as this provides the fault protection.
Things evolve and a metal CU with a tails clamp is deemed to be safe enough these days, making tail faults upstream of the CU’s protective devices extremely unlikely.

agreed, you can do that, it clearly states in the guidlines that you can.
you have answered your own question, why ask it?

 

[timhoward]

agreed, you can do that, it clearly states in the guidlines that you can.
you have answered your own question, why ask it?

Neither myself or @nicebutdim asked any questions including the original one!
This thread was actually resolved in August 2020. You decided to add a comment yesterday, and one of your statements that every TT install needs an up front 100ma S type or 300ma RCD was a bit misleading as it's only one way to comply, hence the further debate to clarify things a bit.
Anyway, I think we are all agreeing so it can probably rest again now!

 

[nicebutdim]

OK
1.Instead of an RCD you can use a MCB as FAULT PROTECTION "IF" the Rod Resistance is low enough to do so.
BUT supposing your Rod Resistance was 50 ohms? 230/50 =4.6A on Fault. This wouldn't be enough to trip a 5A Breaker or fuse.
Answer? Fit a Time Delay RCD Type S ( time delay 100mA ) as FAULT PROTECTION. Even if you used a 5a Breaker as soon as you turn on a cooker or use some other device above 5A load you will lose your supply.
Short Circuit protection ( L-N ) would be protected by the service fuse ( assume 63A or similar ) Fault Protection via the time delay RCD

2. you answered your own question on your original post.
22 ohms on the rod ( which will change in different seasons according to ground conditions )
230/22 = 10.45A.
Again I ask you, would you put a Low rating MCB on the supply as Fault Protection? NO
I would use a Time Delay or Type S RCD.
I hope this clarifies the matter.
I would fit the RCD to CYA ( cover your arse )
All the circuits in the board would be 30mA rcd protected. ( dual RCD or RCBO's )

Tim has summed matters up fairly well in the above post and I don't wish to be drawn into protracted argument that digresses from the point at hand.

Your original comment is below, please read it again.

"TT supply must have an RCD of 100mA Time Delay or a 300mA rcd. The circuits downstream must have an RCD of 30mA for Discrimination ( now called Selectivity )
The RCD is an Earth Leakage Device the older types now banned and obsolete were Voltage operated circuit breakers"

There are indeed circumstances where it would be appropriate to fit an upfront 100mA type S RCD.

There are many circumstances where it would not be required, although fitting one would be perfectly acceptable. I see nothing wrong with this belt and braces approach and would generally agree with it, but with the proviso that the upfront unit incorporate type A sensing.

As for the suggestion that a 300mA RCD is acceptable place of 100mA type S? This may not be appropriate, depending on the installation in question.

I hope this clarifies my 'disagreement' with your original comment. I'm a learner who still has much to learn. I don't think it helps anyone when statements are made that don't align with regulatory requirements and when regulations are quoted to back up an argument at odds with the regulation quoted.

To answer your question; I would not fit a 10mA MCB in the circumstances you describe as doing so would be absurd, not to mention being at odds with the regulations we generally work to.