Wiring a 3 phase table saw

[cjard]

Having bought a second hand 3 phase table saw, I just thought I'd check the wiring before I powered it up

Several loose connections tightened later I have a question about the wiring layout


A 3P+N+E red plug is attached to the machine. The cable has black brown blue and grey. The blue is wired to the E pin of the plug and the others are L1 to L3, N is not connected. The cable goes into an electromagnetic switch on the saw. Here the black brown and grey attach to L1 - L3 and the blue is earth sleeved and attached to the body of the machine. The SWA strands are not connected to anything at either end. A 4 core cable with black brown blue and yellowgreen goes to the motor. The black brown blue attach to switch outputs A B and C and the yellowgreen wire attaches to the body of the machine


Just wanted to check that this seems correct? I think the emag switch uses 115v because there are 2 extra wires on L1 and L3. The motor, I presume, just uses the phases and doesn't require a neutral

 

[flameport]

Colours are somewhat off, but the description of the wiring is correct.

SWA armour should be connected to earth at one or both ends - but if that's been used between the plug and machine is it really SWA? SY cable would be more likely. Either way the armour needs to be connected to earth.

If the magnetic switch is between L1 and L3 it will be 400V, not 115.

 

[cjard]

Fairly sure this is SWA - SY looks more flexible / "plaited" I think - this cable is like.. 18 strands of grey wire that all spiral in the same direction. The gland that wires it to the machine is wrong but i'll sort that, and wire the SWA to the earth pin of the plug too, cheers!

 

[Robin0577]

Although the wiring itself sounds correct electrically, SWA terminated into a plug is considered bad practice, due to the inability to gland it properly into most plugs and to it's lack of flexibility. I would be inclined to replace the SWA with a more suitable 4 core cable of the appropriate size and with the correct colour scheme. H07RN-F heavy duty rubber flex is the norm for power tools and "portable" machinery.

View media item 94256

*By portable I mean connected via a plug and socket as opposed to permanent wiring.

 

[ericmark]

As stated SWA can be glanded into metal plugs but it's a real pain to do and the metal plugs take some finding. Using SY braided cable and teasing the inner core through the braid one can then stroke the braid into a wire and sleeve it and connect to earth. Some cable actually has a copper core under and in contact with the braid common in Europe but not so common in UK.

Using a core as earth then connecting it to braid at machine end may not be as good as connecting at plug but does mean braid is earthed. The glands for braid are horrid to use I would often use a stuffing gland and tease the centre core through the braid. The Hawk gland is the ideal answer with the reversible ring one way for braid the other for SWA but they are expensive.

I personally would not want to use a non armoured cable for a machine where damage is quite likely.