Ever thought about ... ?

I'd expect  the data for semi-enclosed fuses to be a bit variable - the whole point is they use fuse wire made to a certain tolerance, by anyone of a number of suppliers, placed in the holder by hand, and the finer  details of how the wire is tensioned, and may or may not be in contact with the ceramic carrier are outside of the control of the spec-writers.

To compare the modern cartridge fuses have elements that are more like a stamped ribbon, with necks to create multple break points, to break up any arc, and M wells of softer metal to handle overload.

There are (were) a number of fuse designs claiming to meet BS3036, that had various maximum current and PSSC options, though  the common Wylex ones went up to 45A (green spots) for cookers, but had a PSSC of 2kA, the older ones were 1kA. I understand that they will break considerably more without damage to the fuse holder or the unit, , but the limiting factor is the ejection of hot metal out of the ends of the holder in a way that would injure anyone inserting a fuse against a fault. I do not have the standard, but  I presume a version of the MCB not singeing the cheese-cloth test could be used to verify this, though if  such modern thinking pre-dates that standard I don't know,.



And wylex_plugin_mcbs_datasheet_.pdf

suggests some permitted Zs for 5sec and 0,4 seconds that are similar,.

Of course, unlike an MCB, where the step from instant operation to slow thermal is a cliff edge, with a fuse it is less serious - if you get it wrong it opens in 0.5 seconds instead of 0,4, and most folk won't care.



The old sweats advice was always to use the flat cap as an impromptu  'mitten' when inserting fuses into a board that may be live, just in case it arced. I guess a burn mark on the twill is less serious than damage to fingers, and in the same league as a pipe burn on the sweater form smoking while distracted - a thing from a bygone era.

The fact the the BS1361 (or BS88-3) company fuse does not normally blow (even a 60A one) against a BS3036 30A, allows us to put another upper bound on the let-through energy of the old hot-wire fuse - even if it has been rewired in paperclip, the company fuse imposes an upper bound.

regards Mike.

I'd expect  the data for semi-enclosed fuses to be a bit variable - the whole point is they use fuse wire made to a certain tolerance, by anyone of a number of suppliers, placed in the holder by hand, and the finer  details of how the wire is tensioned, and may or may not be in contact with the ceramic carrier are outside of the control of the spec-writers.

To compare the modern cartridge fuses have elements that are more like a stamped ribbon, with necks to create multple break points, to break up any arc, and M wells of softer metal to handle overload.

There are (were) a number of fuse designs claiming to meet BS3036, that had various maximum current and PSSC options, though  the common Wylex ones went up to 45A (green spots) for cookers, but had a PSSC of 2kA, the older ones were 1kA. I understand that they will break considerably more without damage to the fuse holder or the unit, , but the limiting factor is the ejection of hot metal out of the ends of the holder in a way that would injure anyone inserting a fuse against a fault. I do not have the standard, but  I presume a version of the MCB not singeing the cheese-cloth test could be used to verify this, though if  such modern thinking pre-dates that standard I don't know,.



And wylex_plugin_mcbs_datasheet_.pdf

suggests some permitted Zs for 5sec and 0,4 seconds that are similar,.

Of course, unlike an MCB, where the step from instant operation to slow thermal is a cliff edge, with a fuse it is less serious - if you get it wrong it opens in 0.5 seconds instead of 0,4, and most folk won't care.



The old sweats advice was always to use the flat cap as an impromptu  'mitten' when inserting fuses into a board that may be live, just in case it arced. I guess a burn mark on the twill is less serious than damage to fingers, and in the same league as a pipe burn on the sweater form smoking while distracted - a thing from a bygone era.

The fact the the BS1361 (or BS88-3) company fuse does not normally blow (even a 60A one) against a BS3036 30A, allows us to put another upper bound on the let-through energy of the old hot-wire fuse - even if it has been rewired in paperclip, the company fuse imposes an upper bound.

regards Mike.