What are peoples views in regards to this? Does this apply as a minimum of 2 per switchboard?
As in, 2 FSCs in a subboard require 2 RCDs? Or is this total taken as across the whole installation and provided there was already at least 1 on the MSB that the subboard could infact have 1 covering the minimum of 2 installed because the head to the clause indicates "residential installations" which to me seems to be the whole installation not just an individual switchboard
I always read this as per switchboard but I can't actually see anything that points to this although it probably was the intention
Minimum of two RCDs when more than one FSC 2.6.2.4 (b) (ii)
Re: Minimum of two RCDs when more than one FSC 2.6.2.4 (b) (ii)
So for example, if there was a sub board with 2 FSCs, you're asking if there should be 2 RCDs?
Because there might already be one or more RCDs on the MSB...
I'm not even sure that the note explains it in a helpful way.
If there was 2 FCSs, 1 for socket outlets and 1 for lights, having 2 RCDs isn't going to help when all lighting is lost. But it would stop the fridge from going off I guess. However if they were on the same RCD, at least you would know that the fridge was off, because you would have lost all the lights.
Also with 2.6.2.4(a) - saying that having more than one lighting circuit requires them to be on different RCDs, but there's nothing that requires more than 1 lighting circuit to be installed. Someone could wire the lighting in an installation with separate areas and 3 cables back to the switchboard, but connect all 3 to one circuit breaker - so there's only one lighting FSC.
This clause could have done with some requirements that actually had to be met, not ones that were easy to circumvent.
Because there might already be one or more RCDs on the MSB...
I'm not even sure that the note explains it in a helpful way.
If there was 2 FCSs, 1 for socket outlets and 1 for lights, having 2 RCDs isn't going to help when all lighting is lost. But it would stop the fridge from going off I guess. However if they were on the same RCD, at least you would know that the fridge was off, because you would have lost all the lights.
Also with 2.6.2.4(a) - saying that having more than one lighting circuit requires them to be on different RCDs, but there's nothing that requires more than 1 lighting circuit to be installed. Someone could wire the lighting in an installation with separate areas and 3 cables back to the switchboard, but connect all 3 to one circuit breaker - so there's only one lighting FSC.
This clause could have done with some requirements that actually had to be met, not ones that were easy to circumvent.
Re: Minimum of two RCDs when more than one FSC 2.6.2.4 (b) (ii)
First the question WRT whether the rule applies to number if subcircuits in swbd, or in installation.
Easy answer; in the opening sentences:
for option (a): "In all electrical installations where"
for option (b): "In residential installations".
These openings clearly tie the 'trigger' conditions that follow to the installation; not to the switchboard.
The Note makes sense if you know that before these requirements were added (July 2009; effective for NZ April 2010); it was common to have only one RCD for the entire house.
Some of the "better" installers used 2, and almost nobody used more than 2.
But now that these rules have been there a while, an increasing number of users don't have long enough memories.
Wiring all lighting as one FS may be OK for very small installations; but not for larger ones.
It's difficult to set 'hard' requirements that don't invite ridicule for being too onerous in some cases.
So these requirements have to be a bit flexible.
True that means the less scrupulous can get around them; but there are other, higher-level rules in play as well,
eg 1.6.1(d)'s requirement to minimise inconvenience in event of a fault
Easy answer; in the opening sentences:
for option (a): "In all electrical installations where"
for option (b): "In residential installations".
These openings clearly tie the 'trigger' conditions that follow to the installation; not to the switchboard.
The Note makes sense if you know that before these requirements were added (July 2009; effective for NZ April 2010); it was common to have only one RCD for the entire house.
Some of the "better" installers used 2, and almost nobody used more than 2.
But now that these rules have been there a while, an increasing number of users don't have long enough memories.
Wiring all lighting as one FS may be OK for very small installations; but not for larger ones.
It's difficult to set 'hard' requirements that don't invite ridicule for being too onerous in some cases.
So these requirements have to be a bit flexible.
True that means the less scrupulous can get around them; but there are other, higher-level rules in play as well,
eg 1.6.1(d)'s requirement to minimise inconvenience in event of a fault
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