Green break glass over rides for magnetic locks

[Wiz]

Chris, the point I am making in this case, is not that there shouldn't be a green BGU at all, but just that the increase in overall safety of a double-pole over a single pole is very small.

Furthermore, my point isn't that the increase in overall safety in this case is 'too small'. I don't know what 'too small 'would be without more data of just how big the risk actually is.

The point I am asking is where do we stop in promoting recommendations with benefits that are small against the high cost of providing them?

As you rightly say, 'we need to get the balance right'. But how do we do that?

[Chris Houston]

The point I am asking is where do we stop in promoting recommendations with benefits that are small against the high cost of providing them?

That is a tough question.  It it were easy, none of us would have jobs.

I think the double pole BGU is an example where the cost is less than the beenfit.  I guess those who drafted the BS agreed.  If you want to stray from standards, especially one about how to control the risks assiciated with locking fire exit doors, you're going to have to be prepared to convince a much more confrontational debater than the ones you have encountered on here.

[Wiz]

The problem with double-pole EDR (green BGU) is that they offer no protection against two simultaneous cable short-circuit faults. One fault shorting out out one pole and the other shorting out the other pole when neither of the materials providing the shorts are interconnected.

I appreciate this is more unlikely than both poles shorting to the same conductive material, but it could happen.

To ensure that this 'risk' can't occur, I suggest that we 'link' all conductive materials on the cable path of the EDR by means of a cable bond to ensure the scenario above will be prevented.

When my bonding suggestion is agreed, I'll think of another 'what if' scenario to get the costs up even higher!