No, they need not be high voltage rated, just isolated, preferably in oil. At a 100ma over current, the resistor would only have 6kv across it. Most such resistors are on the order of 20cm long. At Jim Lux suggested 1kv/cm that's 20KV in air!
Its wirewound nature would also contribute to quenching ultra high frequency spikes, though I would not try and sell it as an adequate choke for this purpose.
Richard Hull
Created on Saturday, March 24, 2001 6:57 PM EDT by Richard Hull