Mains lead retention.

[G6Tanuki]

I've always been mildly disturbed by some of the ways mains-leads are affixed to radios, in particular situations where the lead passes through a simple hole bored in the chassis [with no grommet] and the only thing stopping it pulling-out is a knot tied in the lead!

My recently-acquired Eddystone S.750 was built like this, though they did go as far as interposing a paxolin washer between the knot and the hole-in-the-chassis...

My 'rework' - at the same time as fitting a 3-core mains lead - was to enlarge the hole in the chassis using one of my trusty Q-Max punches, then fit a stainless-steel [IP67, marine grade] clamp gland.

The new cable then has a couple of short lengths of adhesive-lined heatshrink put over it, one long, one short, to form a stepped bulge; the nylon gripper in the gland clamps on to the thinner part, the fatter part of the bulge being inside the barrel part of the gland.

A cable-tie inside provides additional security against the cable ever being pulled-through.

The result is secure, and safe; I reckon I could probably suspend the radio by its mains-lead and it still wouldn't pull out! It's also in the spirit of current legislation which requires two forms of mechanical retention of mains leads.

[Nickthedentist]

That looks like a good belt and braces solution! Knots might be nice and original but they don't take any of the strain off the wires if the cable gets twisted or generally jiggled around.

I usually go for a plain but tight-fitting grommet where the cable enters a set, followed by a Nylon P-clip fixed to the chassis with a bolt, large plain washer and Nyloc nut.

Alternatively, a cable gland like you've used (though invariably the plastic type), with a >/5mm cable tie in the same manner as you've done, with a drop of superglue between the "tail" of the cable tie and the latch for extra security. Sometimes I wrap thinner cables with a couple of turns of self-amalgamating or PVC insulating tape to help the gland grip. The downside with this approach is that the chassis hole needs enlarging substantially, which would spoil a set for purists.

[pmmunro]

Originally Posted by G6Tanuki

A cable-tie inside provides additional security against the cable ever being pulled-through.

It's also in the spirit of current legislation which requires two forms of mechanical retention of mains leads.

That's a very worthwhile improvement. The compression gland both protects and retains the cable.

What is the legislation that requires two forms of retention of mains leads? Do you have a refernce please?

PMM

[G6Tanuki]

Originally Posted by pmmunro

What is the legislation that requires two forms of retention of mains leads? Do you have a refernce please?

PMM

Not sure exactly where I saw it, but it was in a Statutory Instrument several decades ago [I was looking at it for 3-phase applications in an industrial situation]

[kalee20]

I prefer a detachable lead, the IEC320 connector and mains lead is ubiquitous...

Failing that, a cable gland as G6Tanuki says, works very well!

[turretslug]

If there's space to fit a modern IEC panel plug- usually a C14, sometimes a C6- that's very much my preferred option but the Eddystone 750 is one of those cases where there's too much going on on the limited rear apron area already. My set had a decent brass P-clip with smooth edges retaining the (somewhat perished) original 2-core mains lead, so I re-used this with the slightly thicker 3-core replacement lead (double-sheath with PVC outer and HDPE inner sleeve), a standard PVC grommet squeezed into the original, slightly enlarged chassis hole and a smear of Hellerman lube eased the new cable through it. Once dry, this is quite firm in itself but would certainly not be up to a sharp pull, the brass P-clip adds sure-fire mechanical security.

The heaters in-out IO socket was replaced with an adapter plate for a 1.25" primary-side fuse. I don't like the idea of extra significant-current connections that I won't use anyway, and having two identical connectors for very different functions and voltages seems like a really bad idea to me.

I wince a little when I see knots used to secure cables but it is quite common in older appliances- no doubt something bad happened sometime for a better method to replace it, safety regulations often seem to be reactive.