derating
In the first part of the question there will be only one wire in the conduit, in the second part of the question there will be two wires in the conduit.
Yes. Actually they should be run in the same conduit. You don't ever want to run parallel separately.
Yes they can. There are regulations that cover most jurisdictions regarding how different cables can be contained. It is important that you are knowledgeable about your local requirements before starting the work.
Usually in the industry, we call it metal conduits. Metallic conduit is stronger, more durable, and more fire-resistant than non-metallic conduit. It is often used in industrial, commercial, and hazardous environments. Which included, Rigid Metal Conduit(RMC) Electrical Metallic Tubing (EMT) Intermediate Metal Conduit (IMC) Galvanized Rigid Conduit (GRC) Flexible Metal Conduit (FMC) Liquid-tight Flexible Metal Conduit (LFMC) Hope it works.
derating
You can put three ccc's in a conduit (any size conduit) before you derate. Keep in mind that for single phase loads (lighting, receptacles) the neutral is also counted as a current carrying conductor. This derating factor does not apply to nipples 24 inches long or less. See NEC Table 310.15(B)(2)(a) for full details on derating regarding ccc's.
There are two things here to keep in mind. If you are trying to add more conductors to an existing conduit run use the cross sectional area of the conduit to see if more wires can be fitted. The second thing that's relates to length is the voltage drop at the load. To size the conduit work backwards from the load amperage to size the wires. If a long distance is involved a voltage drop calculation will be needed. Then select the conduit size to accommodate the wires recommended for that load amperage. The length of conduit run is not brought into the equation on de rating wire size it is always about keeping the voltage up at the load end of the run by increasing the wire size and selecting the proper conduit size for that wire.
The simple answer to your question is yes. But there are limits to how many wires can be in any conduit, and the current carrying capacity of the conductors can be affected by distance, ambient temperature, and how many conductors are contained in the same conduit. Other things to consider are, Can you physically fit the wires in there? Would it be easier to run a new conduit? Do you have the manpower necessary to get the work done?
No, the bare copper grounding conductor can not be in a conduit with other conductors. It can be in conduit by itself to provide mechanical protection for the wire.
The NEC PVC conduit fill table provides information on the maximum number of conductors that can be safely installed in a PVC conduit based on the size of the conduit and the size of the conductors.
The amount of conductors per conduit size example code says 3 number 4 conductors in a 1'' conduit
Conduit sizing is based on the number of conductors that are drawn into it. Without the number of 1000 MCM conductors, an answer an not be given.
The electrical pipe fill chart provides information on the maximum number of conductors that can be safely installed in a conduit based on the size of the conduit and the size of the conductors.
Yes. The thing that has to be closely watched is the load on the conductors. The conductors will have to be de-rated as the code only gives amperage rating for three conductors in a raceway. So watch the connected amperage to each load and fill the conduit accordingly. This supersedes the conduit fill requirements rule.
You can have only one current carrying conductor in a conduit, but that conduit must have a slot to relieve the eddy currents that will be created by the transformer effect created by the conductor. It is better to run the neutral or opposite conductor along with the hot conductor together in the same conduit, or through the same penetration, so as to minimize this effect.
A conduit is a set of closed canalization circular or not that assures the free passage of conductors and ensures their continuous protection.