What sort of "fly lead"? Earth I assume?


I cant say I've ever seen anything coming out of a motor terminal box where the windings terminate.


I've only ever seen the motor supply cables going into the motor. I can only assume there's an external earthing point? Is there an internal point too?

Yeah that’s what I mean an earth flylead from the terminal box to the chassis. I don’t know why it would be needed if it’s earthed through the armour gland or an additional core as a cpc.

earthed and seen to be earthed, makes it visible and inspectable without dismantling . electrically not really needed unless there are rubber washers at the joints or antivibration mounts or something.

So it’s acceptable to just run the cpc to the terminal box and leave it as that. I know IP55 motors have a rubber seal between the terminal box and the motor chassis but the screws still create continuity between the box and chassis.

Just because a couple of bits of metal are bolted together, doesn't prove that they are electrically connected.  There may be rubber vibration mounts, paint or even a layer of surface corrosion preventing good contact.  As mapj says, if you run a flylead, you know it really is connected.

This is an example

I wouldn't call that a "flylead" - it's a CPC. If the armour of the SWA is being used as the CPC, it is superfluous. You don't have to use the earth terminal in the box if you don't need it, but you would need it if you used ordinary 4-core cable.

I know it’s not a flying lead but what I meant was Is that earth terminal sufficient as I’ve seen on site them running a banjo on the outside with a flylead to the motor casing.

The short answer is it may not be needed - and there is a tendency to always use banjos and bolts, even in cases where an internal nut like a Prihana would be better (as no need for extra holes in the box) Partly I think because the glands are often sold with a banjo or two in the packet, rather than it being the best solution for all cases, but it saves a separate purchase. There are some house styles that do not rely on the glanded armour as the sole CPC, insisting on using a core as well, and having seen a few examples of truly dire armour termination I can see the point, but getting folk to produce a well terminated armour and cable routes that are not stressed should be enough. It also partly depends on the local inspect/ test regime - you can ask someone to give  an external lead a waggle, as part of a clean and check over without turning off the power, but verification of an internal contact is more involved.