Common in this context is not the power supply common, it means it is the 'Common' terminal WRT the other two (N.C. & N.0.).
Even when using one pair of contacts, it is customary to show power into the COM terminal of the relay, although electrically it will result in the same effect.
Albeit in this case it would not matter, just custom.

 

With noormal AC mains wiring it is better to refer to that side of the circuit as "neutral," not "common", which is a better term than "ground." Certainly the jargon of the realm in electrical discussions can be confusing for those uninformed.

 

With normal AC mains wiring it is better to refer to that side of the circuit as "neutral," not "common", which is a better term than "ground." Certainly the jargon of the realm in electrical discussions can be confusing for those uninformed.

 

With noormal AC mains wiring it is better to refer to that side of the circuit as "neutral," not "common", which is a better term than "ground." Certainly the jargon of the realm in electrical discussions can be confusing for those uninformed.

But the Common in this context is in reference to a relay terminal, NOT the supply.

In any case, ground as used in N.A. is confusing as it is also a term for Earth connection.

 

Should the LINE input be connected to NO terminal or COM terminal?
My vote would be that LINE is connected to NO terminal. Load is connected to COM terminal.
The reason for this you don't want LINE to appear on NC terminal when the relay is not activated.

 

Should the LINE input be connected to NO terminal or COM terminal?
My vote would be that LINE is connected to NO terminal. Load is connected to COM terminal.
The reason for this you don't want LINE to appear on NC terminal when the relay is not activated.

Why not?
If it is not being used it is moot.

 

Why not?
If it is not being used it is moot.

LINE voltage stays put and doesn't move. One less thing to go wrong from an accidental short to NC.

 

LINE voltage stays put and doesn't move. One less thing to go wrong from an accidental short to NC.

The concern that I have is that on some small relays the moving contact is solidly connected to the relay frame. So the entire relay frame, and any conducting material it is mounted on, is connected to the switched circuit. THAT is a real potential problem.

 

I only use reputable relay manufacturers, the relay armature and contacts etc are always well insulated from any frame point.

 

Should the LINE input be connected to NO terminal or COM terminal?
My vote would be that LINE is connected to NO terminal. Load is connected to COM terminal.
The reason for this you don't want LINE to appear on NC terminal when the relay is not activated.

Personally, I'd place it on com, which would maintain the logic of NC/NO, as well as making them available without rewiring, should a need for the other logic arise.