There is an article in PE and I have just received it via email.
I am disappointed that the article seems to suggest that it contains all you need to know yet no mention is made of earthing systems
Does BS 7671 really require we keep the touch voltage below 50 V?
For TT systems that use RCDs, and for ‘persistent’ touch voltages , yes - 411.5.3 (ii).
The TT systems that have such low loop impedances that overcurrent devices can be used, there isn't a specified limit, but as the system then approximates to TN systems any reasonable leakage current isn't likely to do any harm.
- Andy.
Does BS 7671 really require we keep the touch voltage below 50 V?
For TT systems that use RCDs, and for ‘persistent’ touch voltages , yes - 411.5.3 (ii).
The TT systems that have such low loop impedances that overcurrent devices can be used, there isn't a specified limit, but as the system then approximates to TN systems any reasonable leakage current isn't likely to do any harm.
- Andy.
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