Induced Voltages

Are all of the phase conductors in one cord set? If so then the vector sum of the induced currents will be zero. If they are stand alone single conductors on each reel then yes you could have an inductive effect in the metal reel and you might have some sort of weird circulating current going on in the reel.

I think I would be more interested in voltage drop. What size are all of the conductors and what are their total lengths?

Answer. You will get heat built up in the coils due to induction from the current going in. This will burn the cable outer sheathing if run for to long. If the real is made of iron/steel the effect will be far greater.

Farmer1's comment did make me think for a second. You will see some mutual heating from the coils of wire. You might want to think about de-rating them based on the number of coils present.

Table 5C of the CEC (Canadian Electrical Code) offers the following de rating factors for cables bundled together.

Just FYI, I have a commercially-produced 20m extension cord (240V, 50Hz, 1ph) on a reel. It's rated at 3120W fully extended, and 720W fully wound. It has 43 turns when fully wound.

Hello dg1258

As stated above, heat build-up in the flexible cables is going to be the main concern.

You could calculate it out, but may be easier to embed a couple of thermocouples at the centre of each reel, and monitor it over a period of time - Winter through Summer.

You give your Location: north east, but is that North-east US or North-east Sahara? There is quite a difference in ambient temperatures.....

Kind regards....

Yes all the conductors are in one cable per motor,voltage drop has been factored in.Sounds like the biggest thing is just heat build up in the buried turns on the reel.And that will depend on a bunch of other things,like load,how much on reel,air temp.Thanks for your thoughts.Oh and it's North East USA.