gkenyon said:

Looking for the absence of something is never a good way to 100 % verify something

And just to clarify, before someone asks, yes I also mean when we try to "prove dead". I used the term "prove dead" on purpose here, because we are not, in fact, doing that, but rather "checking for the absence of voltage" ... this does not (always) mean that the system is completely "dead", just that you can't detect voltage at that point in time.

'Absence of evidence is not evidence of absence.'

gkenyon said:

Looking for the absence of something is never a good way to 100 % verify something

And just to clarify, before someone asks, yes I also mean when we try to "prove dead". I used the term "prove dead" on purpose here, because we are not, in fact, doing that, but rather "checking for the absence of voltage" ... this does not (always) mean that the system is completely "dead", just that you can't detect voltage at that point in time.

'Absence of evidence is not evidence of absence.'

What is your standard of proof? More likely than not, or beyond all reasonable doubt?

I think that I prefer the latter for proving dead.

Proving a negative has never been easy. If I claim to be able to run a mile in 4 minutes, and then do so (most unlikely) I have proved my ability, even though I might not be able to repeat it straightaway.

However, if I claim not to be able to run, how do I prove it? You might very reasonably say that I am just not putting in any effort.

Chris Pearson said:

What is your standard of proof? More likely than not, or beyond all reasonable doubt?

Legal proof vs scientific proof is a good question - legal has two (one for civil, one for criminal).

Scientific enquiry uses a slightly different approach. Philosophical truth is perhaps another thing.

Engineers have to balance all of them

Chris Pearson said:

I think that I prefer the latter for proving dead.

That's interesting ... and it depends on how you define "dead". It's entirely possible to 'prove dead' using a voltage indicator and traditionally taught methods, and have 'danger' present (as defined in EAWR) if there is a minor and seemingly inconsequential action that doesn't involve operating isolators, or switches. Removing an earthing, bonding or protective conductor connection under conditions of diverted TN-C or TN-C-S system neutral currents is a good example ... but there are other conditions that might lead to failure to detect the potential danger ... perhaps we could term these 'errors or omissions', or simply 'never thought of that'.

Chris Pearson said:

What is your standard of proof? More likely than not, or beyond all reasonable doubt?

Legal proof vs scientific proof is a good question - legal has two (one for civil, one for criminal).

Scientific enquiry uses a slightly different approach. Philosophical truth is perhaps another thing.

Engineers have to balance all of them

Chris Pearson said:

I think that I prefer the latter for proving dead.

That's interesting ... and it depends on how you define "dead". It's entirely possible to 'prove dead' using a voltage indicator and traditionally taught methods, and have 'danger' present (as defined in EAWR) if there is a minor and seemingly inconsequential action that doesn't involve operating isolators, or switches. Removing an earthing, bonding or protective conductor connection under conditions of diverted TN-C or TN-C-S system neutral currents is a good example ... but there are other conditions that might lead to failure to detect the potential danger ... perhaps we could term these 'errors or omissions', or simply 'never thought of that'.