I have seen only small performance hits, but depending on the source of noise, the effect could be huge. Electrical cables, transformers, motors, power supplies and many types of electronic equipment can cause interference. Indicated by a high bit-error rate (BER), the problem can sometimes be solved by re-routing the cable(s). Otherwise, metal raceway or shielded cable are possible solutions.
Yes there would be some interruptions and it may cause some effect. This cannot be avoided. how ever it may have been shielded, still the effect can be a minimum only. The magnetic effect would not be there but we can feel some electrical disturbances and fluctuations.