Since you need power all the way to the outlet on the left, then the black and white must be continuous all the way. Is there no ground wire (either green or bare) in the metal conduits? I believe current code requires that, but your wiring may predate that and use the metal conduit for that purpose. I'm not sure if you need to retrofit that but, if not, at least make that there is continuity all the way from the main ground to the ground at the outlet. I assume that's a 3-prong, grounded outlet. If it's not, then there are additional issues.

Now, regarding the light, you have power at the switch box with the black wire. Connect that to one screw on the switch and connect the red wire to the other. The red wire now becomes the power source back at the light, and connect it to the black wire on the fixture. The white and ground wires from the Romex are connected to the similar colored wires on the light fixture. Are the switch and light boxes metal or plastic?

Thank you. There is not a ground or green wire in the metal conduit, it is already pre-existing wire that runs in the ceiling through floor joists, and I cannot get to it...so I am trying to just use the metal conduit that is already there.

it does go to a 3-prong outlet.

As for the light and witch boxes, I have to install new ones. I was going to do plastic...unless you think one way is better than the other.

Maybe Ron Natalie should comment on this, but if you do use plastic boxes, you have to make sure the ground wires are connected to each other AND NOT TO THE WHITE NEUTRAL! i'm not sure what the protocol of multiple grounds is. If you use metal boxes, then the conduits will be automatically connected together. If the ground wire in the Romex is connected to a metal ceiling box, then your outlets will be properly grounded. I would open up the box with the 3-prong receptacle in it and confirm that the ground connection is to the metal box itself, and not to the white wire. Back in the day, many people incorrectly used the ground circuit as the neutral.

You say that the old connections are with metal conduit. Is this rigid, pipe-like conduit, or flexible BX type. If it is rigid, you might be able to pull new conductors through it.

flexible bx

OK, so you probably can't pull new wires.

Just to expand on the comments by mtvmike - The black and white wires at the light are providing continuous power to the switch and the last receptacle, and the red is being used to create a switch loop for on/off power to the light.

At the light - the white (neutral) wires and black (hot) should be connected together so that they go forward and also provide power to the switch. The whites will also be pigtailed and connected to the light's white wire. The red wire at the light will be connected to the black terminal of the light.

At the switch the red wire will connect to one terminal of the switch. All the blacks (in and out) will be pigtailed together, and there will be a black wire pigtailed and connected to the other terminal of the switch. The switch now provides a connect/disconnect between the black wire and the red wire, which provided on/off for the light. At the switch the two whites will be pigtailed togther. Coming out of the switch, to the receptacle, you will have only black and white wires.

There are two (maybe more) things to be aware of. Your light switch will not have a ground unless you run new 14/3 wire from the light to the switch. This means that some newer electronic switches may not work correctly - probably not a big issue. The flexible steel shield on most old residential wiring is for protection, and is not considered an adequate ground, so your receptacle at the end should be treated like it is ungrounded, The simple fix is to use a GFCI at that receptacle, unless you want to pull new wire. However, if your metal conduit is solid steel (not flexible), it may be an acceptable ground, but that type of conduit is not common in a residence.

Bruce

Careful, old BX (armored flex) can be bad news. The armor was used as a ground. In time corrosion would build up between the rings and cause the ground's resistance to increase. There were cases where a fault current from a defective appliance heated up the armor until it glowed red and started a fire. A bonding strip was eventually added to deal with that problem. Look for it in yours. Modern MC cable has an insulated green grounding conductor.