UK RCD/ combined afdd breakers

[timhoward]

I'm actually a bit confused what the actual question is and if it's been answered! ;-)
When you say it's for fault protection are you referring to the AFDD part of it, or meaning it's installed to provide ADS for an installation, e.g. a main switch or up front device on a TT system?

,is there a reg No that determines those values please .

The time/current criteria is in Appendix 3 of 18th, page 363
Also see reg 643.8, note underneath.
However if it is for fault protection and providing ADS for an installation then chapter 41 applies.
If we can help more then feel free to tell us a bit more about how/where this thing is installed, and what you are unsure of. ;-)

 

[Razzle12]

I'm actually a bit confused what the actual question is and if it's been answered! ;-)
When you say it's for fault protection are you referring to the AFDD part of it, or meaning it's installed to provide ADS for an installation, e.g. a main switch or up front device on a TT system?



The time/current criteria is in Appendix 3 of 18th, page 363
Also see reg 643.8, note underneath.
However if it is for fault protection and providing ADS for an installation then chapter 41 applies.
If we can help more then feel free to tell us a bit more about how/where this thing is installed, and what you are unsure of. ;-)

Hi Tim
I'm working on a youth hostel ,and this is a brand new install ,this relates to one of two three phase boards ,of which almost every single phase breaker is a combined RCD/AFD device ,just would like to know the maximum Ms for the x1 test at 30mA.
Regards

 

[timhoward]

Wow, sounds like someone was flush with cash! Do you have a photo?!

Anyway, posts 2 and 3 are correct, irrespective of the fact they are combined devices, maximum 300ms at 30ma (x1), maximum 40ms at 150ma (x5).

The x5 time still needs to be complied with and if you only have one box to write a result (like the latest NAPIT model form) you'd write down the biggest x5 value.

(The only extra complexity is if the earthing is TT then the x1 would need to be under 200ms)
Hope that helps.

 

[Razzle12]

Wow, sounds like someone was flush with cash! Do you have a photo?!

Anyway, posts 2 and 3 are correct, irrespective of the fact they are combined devices, maximum 300ms at 30ma (x1), maximum 40ms at 150ma (x5).

The x5 time still needs to be complied with and if you only have one box to write a result (like the latest NAPIT model form) you'd write down the biggest x5 value.

(The only extra complexity is if the earthing is TT then the x1 would need to be under 200ms)
Hope that helps.

Hi Tim
Thanks so much for that ,and it's a TNS SYSTEM ,and the device is for fault protection and not additional protection so it should be the highest result on the x1 setting at 30 mA
Many thanks
Can send pic tomorrow if you want ,and yes guess the boards and breakers are expensive ,and was designed by Siemens.
Regards
Ray

 

[Julie.]

I am struggling to understand this.

You have a cu, (std switch on incoming) and each outgoing circuit has a combined rcd/afdd - is this correct?

If so where is the overcurrent protection for each circuit (fault and where needed overload)?

 

[Razzle12]

I am struggling to understand this.

You have a cu, (std switch on incoming) and each outgoing circuit has a combined rcd/afdd - is this correct?

If so where is the overcurrent protection for each circuit (fault and where needed overload)?

As far as I'm aware these are MCB/RCD double pole devices with AFD protection ,these are bespoke boards made especially for the job I'm on . Hope this helps ,but thanks guys and girls I have all the info now .
Regards
Ray

 

[timhoward]

Honestly I'm a bit baffled too, I'm aware of a Siemens MCB + AFDD product, and ordinary RCBO's, and some clever lego-like add on units to add AFD protection (see below), but I've never heard of an AFDD and RCD combo without overload protection too.
Prepared to be proved wrong, and intrigued to see a photo.
I'm concerned that I have given you the wrong answer to what might turn out to be the wrong question!

 

[Julie.]

As far as I'm aware these are MCB/RCD double pole devices with AFD protection ,these are bespoke boards made especially for the job I'm on . Hope this helps ,but thanks guys and girls I have all the info now .
Regards
Ray

Ahh so rcbo/afdd devices NOT rcd/afdd.

They are quite different from rcd/afdd.

I think you need to check exactly what you have as the question you asked doesn't appear to reflect the equipment you have.

 

[Razzle12]

Honestly I'm a bit baffled too, I'm aware of a Siemens MCB + AFDD product, and ordinary RCBO's, and some clever lego-like add on units to add AFD protection (see below), but I've never heard of an AFDD and RCD combo without overload protection too.
Prepared to be proved wrong, and intrigued to see a photo.
I'm concerned that I have given you the wrong answer to what might turn out to be the wrong question!

View attachment 87051

Hi Tim
I'll send you a pic of the device.
Tomorrow.
Regards
Ray

 

[Razzle12]

Hi Tim
I'll send you a pic of the device.
Tomorrow.
Regards
Ray

Hi Tim
Apologies ,yes these are rcbo/Afdd devices,but will send pic tomorrow many thanks guys.snd girls .