I'm guessing it's plumbing, not conduit. Unless you actually see wires running through the tubing, I'm not convinced it's conduit. In the US only certain types of conduit are listed for use, and I'm sure they are similar in Canada. Copper is not among those listed, so it's not likely it would be approved by an inspector.
In a comment you mentioned that the pipe was connected using "nuts", and therefore could not be used for water. However, I disagree. A union is a fairly common fitting in plumbing. In fact, you'll probably find some if you look at the plumbing for the water heater in your house.
Update:
After further searching National Electrical Code, I found this...
National Electrical Code 2014
Article 344 Rigid Metal Conduit: Type RMC
II. Installation
344.10 Uses Permitted.
(A) Atmospheric Conditions and Occupancies.
(2) Red Brass RMC. Red brass RMC shall be permitted to
be installed for direct burial and swimming pool applications.
(B) Corrosive Environments.
(1) Galvanized Steel, Stainless Steel, and Red Brass
RMC, Elbows, Couplings, and Fittings. Galvanized steel,
stainless steel, and red brass RMC elbows, couplings, and
fittings shall be permitted to be installed in concrete, in
direct contact with the earth, or in areas subject to severe
corrosive influences where protected by corrosion protection
and judged suitable for the condition.
(C) Cinder Fill. Galvanized steel, stainless steel, and red
brass RMC shall be permitted to be installed in or under
cinder fill where subject to permanent moisture where protected
on all sides by a layer of noncinder concrete not less
than 50 mm (2 in.) thick; where the conduit is not less than
450 mm (18 in.) under the fill; or where protected by corrosion
protection and judged suitable for the condition.
Which means it's possible the conduit is not copper, but red brass. According to wikipedia, red brass may be 85% copper, 5% tin, 5% lead, and 5% zinc.
Of all the homes I help oversee the construction of, the main thing that was followed when it comes to lightning protection is no sharp bends in the cable, or uphill runs. Always going down to ground. It can be run through walls, by means of drilled holes through the plates, so a close proximity of a non conductive PVC will be no problem. If you want to be safe, get a small gap between the conduit and the cable, though I think it does not need to be much say 1/2"to an 1". Since static electricity carries over the surface of the wire and not through the wire, which is the reason the cable is loosely braided, a little space between the two should suffice, just to be sure.
Best Answer
Use a EMT-to-NM (or GRC-to-NM) combination coupling
They make fittings specifically for transitioning from conduit to a cable, such as an Arlingtion 8600 or equivalent. One of these can be used to keep detritus out of the end of the EMT and strain-relief the cable where it exits the EMT sleeve.