Newfutile 

What exposed conductive parts can people touch whilst having a hand on the handrail, which is possibly an extraneous conductive part?

Good point, simultaneously accessible is often forgotten about.

Sparkingchip said:

What exposed conductive parts can people touch whilst having a hand on the handrail, which is possibly an extraneous conductive part?

No argument there but as far as I can see, if something is deemed an extraneous conducive part, the current edition of 7671 requires MPB to be in place irrespective of whether there are accessible exposed conductive parts or not. 
The 16th Edition made it clear in 413.02.04;

Or perhaps, there was no need for the current edition of 7671 to convey the common sense in Sparkingchip’s remark? 

far as I can see, if something is deemed an extraneous conducive part, the current edition of 7671 requires MPB to be in place irrespective of whether there are accessible exposed conductive parts or not. 

Which in these days of portable Class I appliances, not to mention extension leads, is probably no bad thing.

  - Andy.

far as I can see, if something is deemed an extraneous conducive part, the current edition of 7671 requires MPB to be in place irrespective of whether there are accessible exposed conductive parts or not. 

Which in these days of portable Class I appliances, not to mention extension leads, is probably no bad thing.

  - Andy.