Wiring Diagrams

[Deleted member 26818]

What I'm asking Tony is, will the contactor suffer any damage, if one or more of the phases are isolated?
It's been a while since I've had much to do with contactors, but I seem to remember that they could become damaged if any of the phases were out of balance, or disconnected for any reason.

 

[Knobhead]

Ahh, got what you’re on about now. If the contactor was feeding a motor then yes removing a fuse will causes problems with imbalance and the O/L’s will trip. But for a lighting circuit you have no O/L’s so a single fuse can be pulled to isolate 1/3 of the loading with no problem.

 

[Deleted member 26818]

Thanks Tony, what about these latching types, that some one suggested being used?

 

[Knobhead]

More bloody trouble than they’re worth, same number of switch wires but two coils to go wrong and all the mechanical bits to jamb up! Don’t even think about it!

 

[oxocube]

More bloody trouble than they’re worth, same number of switch wires but two coils to go wrong and all the mechanical bits to jamb up! Don’t even think about it!

I think you will find that most contactor maufacturers reccommend the use of latching contactors for lighting circuits, you're guessing they know.

 

[Knobhead]

If you want to use them then do so, I don’t like them.

 

[kathwilcox]

Can someone suggest any books or material I can access for the wiring diagrams? I find visual aids a lot clearer then simply being told how to do it.

try the jtl electrical installations books, theres level 1 and 2, they have decent diagrams and also explain thing reasonably well, there about £20 each or you may be able to get them from the libary.

 

[ackbarthestar]

If you go with 3-phase lighting (single phase lights) you'll need to take separate neutrals back to the DB for each phase otherwise you'll need linked mcbs.

 

[Knobhead]

Good point.

View attachment 7736

 

[zulfim]

Thanks, Tony
Your diagram was helpful.

One more question....I will be bringing 3-phase+neutral via 6mm SWA into my CU.
In order to supply the contactor do I just tap-off from one of the supplies! ie Brown phase?

Regards zulfim

 

[ackbarthestar]

Thanks, Tony
Your diagram was helpful.

One more question....I will be bringing 3-phase+neutral via 6mm SWA into my CU.
In order to supply the contactor do I just tap-off from one of the supplies! ie Brown phase?

Regards zulfim

Firstly, you must protect the coil circuit with a 6A MCB, the coil will not load the circuit very much.
If its a 230V control coil, its any phase plus neutral otherwise you'll need to use 2 phases (400V).

 

[Knobhead]

As ackbarthestar says protect the switch and coil with a smaller MCB or fuse. Use phase and neutral for the control. 415V is not acceptable on a control switch.

NBP will probably shoot me down for this!
Only joking Paul if you read this.

 

[ackbarthestar]

As ackbarthestar says protect the switch and coil with a smaller MCB or fuse. Use phase and neutral for the control. 415V is not acceptable on a control switch.

NBP will probably shoot me down for this!
Only joking Paul if you read this.

Yep, absolutely correct don't use 400/415V on single pole two way light switching - better make sure when you order the contactor it has a 230V coil.