Ferrule crimps

The thing about using the correct ferrule size and correct faceted tool is key - there have been examples of expensive equipment needing to be recalled because the crimps 'fell off' in use, when in reality they were incorrectly selected or installed
If you don't have the right tooling, then in that case bare stranded wire under a screw terminal is  less likely to fail than incorrectly ferruled stranded wire under the same screw...

Equally correctly fitted ferrules can do wonders for taming the ' whisker problems' that occur otherwise when stranded wires have to be terminated in the field in poor light or with poor access.
Note that there are special ferrules for allowing wires to share a terminal while the single wire ones can be persuaded, it is not good practice as the insulation may not seat in the cone properly.
Equally BS 7671 has not changed - the professional judgement is as it always was yours to make, but it maybe that local house rules or insurance requirements have been updated somewhere and this is what your friend is referring to.
Mike

The thing about using the correct ferrule size and correct faceted tool is key - there have been examples of expensive equipment needing to be recalled because the crimps 'fell off' in use, when in reality they were incorrectly selected or installed
If you don't have the right tooling, then in that case bare stranded wire under a screw terminal is  less likely to fail than incorrectly ferruled stranded wire under the same screw...

Equally correctly fitted ferrules can do wonders for taming the ' whisker problems' that occur otherwise when stranded wires have to be terminated in the field in poor light or with poor access.
Note that there are special ferrules for allowing wires to share a terminal while the single wire ones can be persuaded, it is not good practice as the insulation may not seat in the cone properly.
Equally BS 7671 has not changed - the professional judgement is as it always was yours to make, but it maybe that local house rules or insurance requirements have been updated somewhere and this is what your friend is referring to.
Mike