Splicing submersible pump cable is part and parcel of every submersible pump installation because every submersible pump installation has at least one splice between the motor leads and the pump cable.
Although it sometimes is necessary to splice two lengths of pump cable together in very deep-set applications, it is always better to use a single length of pump cable from the surface to the motor lead. If you have a very deep pump setting, most pump distributors have access to cut lengths of pump cable in lengths longer than 1,000 feet.