Plug in RCD downstream of an RCBO CU
 

Hi All,

Since my "power" circuits got upgraded to the then gold standard 17th edition about 10 years back with all circuits on RCD or RCBO protection, I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool) is something worth doing if using electrics outdoors?

What does the team think?

TIA

Chris

Plug in RCD downstream of an RCBO CU
 

On Fri, 29 May 2020 05:43:03 -0700 (PDT),
wrote:

Hi All,

Since my "power" circuits got upgraded to the then gold standard 17th edition about 10 years back with all circuits on RCD or RCBO protection, I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool) is something worth doing if using electrics outdoors?

What does the team think?

TIA

Chris
You won't normally get any discrimination so either the local,
upstream or both could trip, however look at the follow ups to "F"
(Frank's) thread this morning, there could be an argument for an
"active" second RCD purely for the latching action.

Plug in RCD downstream of an RCBO CU
 

On Friday, 29 May 2020 13:43:05 UTC+1, wrote:
Hi All,

Since my "power" circuits got upgraded to the then gold standard 17th edition about 10 years back with all circuits on RCD or RCBO protection, I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool) is something worth doing if using electrics outdoors?

What does the team think?

TIA

Chris

it won't add anything, other than ability to trip if the main one fails. Possible but not likely.


NT

Plug in RCD downstream of an RCBO CU
 

On 2020-05-29 14:00, Graham. wrote:
On Fri, 29 May 2020 05:43:03 -0700 (PDT),
wrote:

Since my "power" circuits got upgraded to the then gold standard 17th
edition about 10 years back with all circuits on RCD or RCBO protection,
I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool)
is something worth doing if using electrics outdoors?

You won't normally get any discrimination so either the local,
upstream or both could trip, ...

Your plug-in RCD may be more sensitive than your fixed RCD/RCBOs,
e.g. 10 mA vs 30 mA, which would give some extra protection for
outdoor use.

If the plug-in RCD is electronic it might trip faster than the fixed
one and give discrimination. If it's electromechanical then it won't.

(Discrimination is the ability for the closest protective device to
a fault to trip. In this case discrimination would mean the ability
to have the plug-in RCD trip rather than the one in the distribution
board.)


--
Graham Nye
news(a)thenyes.org.uk

Plug in RCD downstream of an RCBO CU
 

On 29/05/2020 13:43, wrote:
Hi All,

Since my "power" circuits got upgraded to the then gold standard 17th edition about 10 years back with all circuits on RCD or RCBO protection, I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool) is something worth doing if using electrics outdoors?

What does the team think?

Nope...

Just two devices to go reset if you get a trip!


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Plug in RCD downstream of an RCBO CU
 

On 29/05/2020 14:00, Graham. wrote:
On Fri, 29 May 2020 05:43:03 -0700 (PDT),
wrote:

Hi All,

Since my "power" circuits got upgraded to the then gold standard 17th edition about 10 years back with all circuits on RCD or RCBO protection, I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool) is something worth doing if using electrics outdoors?

What does the team think?

TIA

Chris
You won't normally get any discrimination so either the local,
upstream or both could trip, however look at the follow ups to "F"
(Frank's) thread this morning, there could be an argument for an
"active" second RCD purely for the latching action.


I think you have got the terms mixed up (or just missed a word out).

An active RCD is non latching ie trips with a powercut

A passive RCD is latching ie will not trip with a powercut

--
Adam

Plug in RCD downstream of an RCBO CU
 

On Friday, 29 May 2020 17:52:54 UTC+1, Graham Nye wrote:
On 2020-05-29 14:00, Graham. wrote:
On Fri, 29 May 2020 05:43:03 -0700 (PDT),
wrote:

Since my "power" circuits got upgraded to the then gold standard 17th
edition about 10 years back with all circuits on RCD or RCBO protection,
I've consigned my plug in RCDs to the cupboard.

But I'm wondering if having a more local RCD (40 foot nearer the tool)
is something worth doing if using electrics outdoors?

You won't normally get any discrimination so either the local,
upstream or both could trip, ...

Your plug-in RCD may be more sensitive than your fixed RCD/RCBOs,
e.g. 10 mA vs 30 mA, which would give some extra protection for
outdoor use.

they're normally 30mA though

If the plug-in RCD is electronic it might trip faster than the fixed
one and give discrimination. If it's electromechanical then it won't.

(Discrimination is the ability for the closest protective device to
a fault to trip. In this case discrimination would mean the ability
to have the plug-in RCD trip rather than the one in the distribution
board.)

I don't think that's likely.


NT