AJJewsbury:
Hang on Andy,
The change was advertised quite clearly, on Page 5 of BS 7671, which says that Chapter 53 has been completely revised.
Regulations 531.3.4.1 and 531.3.6 are definitely included in that.
But no-one went around saying "Big change in the 18th - RCD sockets/FCUs no longer permitted" - so I still reckon it was easy to overlook that particular implication (unlike SPDs or AFDDs).
the installer must ensure that such devices can provide isolation in accordance with Regulation 531.1.1
I've been wondering about what exactly was meant by "Devices for protection against electric shock by automatic disconnection of supply shall be suitable for isolation..."
Do they mean that if ADS is activated that the circuit must be automatically and immediately isolated (so 3mm+ contact gaps, also disconnecting N in TT systems etc) or just that the same device used for ADS can also be used for manual isolation.
For instance, with fuses I can easily ensure a 3mm gap by pulling the fuse out, but I'm not sure I can if the fuse blows of its own accord (thinking of rewireable fuses, while the fusewire often vapourises entirely, sometimes you just end up with a small break).
And (depending on what we decide 'low resistance' of 461.2 means) is this the end of SP switching RCBOs (and possibly single pole MCBs too).
If it's just manual isolation is needed, then things get a lot simpler.
- Andy.
AJJewsbury:
Hang on Andy,
The change was advertised quite clearly, on Page 5 of BS 7671, which says that Chapter 53 has been completely revised.
Regulations 531.3.4.1 and 531.3.6 are definitely included in that.
But no-one went around saying "Big change in the 18th - RCD sockets/FCUs no longer permitted" - so I still reckon it was easy to overlook that particular implication (unlike SPDs or AFDDs).
the installer must ensure that such devices can provide isolation in accordance with Regulation 531.1.1
I've been wondering about what exactly was meant by "Devices for protection against electric shock by automatic disconnection of supply shall be suitable for isolation..."
Do they mean that if ADS is activated that the circuit must be automatically and immediately isolated (so 3mm+ contact gaps, also disconnecting N in TT systems etc) or just that the same device used for ADS can also be used for manual isolation.
For instance, with fuses I can easily ensure a 3mm gap by pulling the fuse out, but I'm not sure I can if the fuse blows of its own accord (thinking of rewireable fuses, while the fusewire often vapourises entirely, sometimes you just end up with a small break).
And (depending on what we decide 'low resistance' of 461.2 means) is this the end of SP switching RCBOs (and possibly single pole MCBs too).
If it's just manual isolation is needed, then things get a lot simpler.
- Andy.
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