they actually chafe the wires.

No go on Boeings in vibration areas such as wing leading and trailing edges per SWPM.

String is better as it does not chafe so much, and snag when harnesses are pulled through. I remember there was a big hoo-ha at Uncle Henry s factory about job demarcation. Electricians tied the harness, a painter then had to apply varnish to the knots, then an electrician had to return and trim the tail after the varnish dried :-)

Imagine the furore when management introduced a new type of harness tie on RB211, read across from the V2500, that was the new kid on the block in the Derby shop at the time. The new string did not require varnish to seal the knot, and did not fray, and the management wanted the fitters to do all the work!

What propnut said - Boeing procedures specifically ban plastic ties because they cause increased wire chafing compared to the fabric ties. I don't think Boeing even allows them in low vibration areas.

During an engine development ground test, we had some test equipment wire bundles secured out of the way using nylon zip ties. One bundle was secured to a 5000 PSI titanum hydraulic line supplying the thrust reverser actuation system. Approximately 1500 engine cycles into the test, the zip tie abraded through the hyd line causing it to burst.

I have also seen many piston-powered general aviation engine mounts (Typically welded 4130 steel tube assemblies) damaged or destroyed by using zip ties to secure items to the mount. A little bit of grit gets under them and the vibration just abrades right through the tube.

That made me laugh!