Hi dr_alinaeem,
I think there is a hand held piece of test gear,
which is intended to indicate fuse-break times.
I think it came about because of the legislation
about bonding. (earthing)
In certain situations the fuse-blow-time dictates
the current carrying capacity of the bonding.
It is sometimes necessary to improve the bonding
until the fuse blows within the time specified
under the legislation,
as a legal requirement.
If the requirement is not met, the 'responsible
person' would not 'sign-off' the installation,
this led i think to these small testers which
would indicate the time taken for the fuse to blow.
Although i have seen them, i have never used one
nor taken any notice of them.
I would imagine such an item could also be used on
a 'normally-closed' contact set, but you would
have to check out its method yourself.
Maybe others have more knowledge of this item
than i do.
Regards, John