A power line for an electrical submersible pump has three metallic
impermeable tubes. A single electrical conductor is located within each
of the tubes. Each conductor has at least one elastomeric insulation
layer surrounding it. An annular portion of the insulation layer of each
of the electrical conductors is in tight contact with the tube to form a
seal. The annular portions may be annular crimps formed in the tube at
intervals. The annular portion could also be a continuous seal caused by
swelling of the insulation layer due to contact with a hydrocarbon.