Lighting Control

Yes. Of course you can.

They will no longer be independent of each other but you can do it.

You can do it but it requires special switches known as "three-way" and three wires between between switches/fixtures. You will have to replace everything that you have and buy specially marked local, photocell, and occupancy switches. There are many variations of exactly how the wiring is done depending upon the exact feedpoint, switch, and light fixture location.

Here's a link to get you started, if you don't feel comfortable then hire an electrician to do the work for you.

Most definitely agree, and I've seen them screw it up too.

Why would you want to do this?

You would need to ensure that both circuits are on the same breaker and phase, otherwise you could have problems with isolation or letting the smoke out.

Put them in parallel and all is good.

Not if the combined amperage exceeds the circuit capacity.

Thats for OP to decide.

Not really. It's for his local electrical code to decide.

Since its a theoretical question we can live without the code. We dont even know where OP is or what the purpose is.

Maybe a school project.

If he is in the USA, he had better be following the NEC.

I hope they are operated from the same leg or phase. Otherwise fireworks guaranteed.

I hope both circuits are on the same breaker or at least the same phase.

Call an electrician. Don't forget to explicitly explain the logic of when you want each of these sets of lights are supposed to be ON and OFF.

The words, " photocell" and "occupancy sensor" , provide two different functions. A photocell sensor is usually used in an application where you want a circuit to be energized when there is change in ambient light, such as a security light turning on at dusk and shutting off during daylight hours. An occupancy sensor is more akin to a motion sensor where the circuit is energized regardless of the presence of ambient light or complete darkness.

Both the photocell and the occupancy sensor should already be wired with a " switch" in the circuit, being that a circuit breaker or at least a spst control.

What do you mean by connect together? Do you want them on and off at the same times, or, do you just want to use the same mains supply for both circuits?

What does "Sama" mean?

yes it can be done! Logically the controls can be either an Or, And, or a combination of both circuits, as long as they all share the same phase..

The hard part is getting a definition of the pronoun "it".

The "it" definition can be defined as anonymous as the OP...

Yes it can be done. Are you using line voltage or lower voltage AC/DC. If it is under 50 volts you can probably do it, otherwise get a professional. You will need a DPST switch and a DPDT relay of the suitable voltage. As per RedFreds concerns below.

Basically when the switch is off the relay is denergized and the motion detector is in control. When the switch is turned on, the relay is energized supplying current to the lamp.

The relay contacts are wired as follows, center or wiper goes to the device. The NC contact(s) go to a constant supply voltage. The NO contacts are wired to the relay energizing contacts. When the switch is activated, current is supplied to the relay coil as well as the N.O. contacts energizing the device.

I did this for the same reason. As our power is unreliable, I used a 12 volt LED system from Costco. Put a car battery on the roof with a 10 watt solar panel and charge controller. Works great.

Simple answer is that provided the two circuits are on the same breaker and that load conditions are favourable, then connecting the two together downstream of both the sensor and the switch will produce a circuit where the lights are controlled by the sensor when the switch is open, and permanently on when the switch is closed. No ancillary equipment is required.