The only issue with 'Phantom' that you need to actively avoid is plugging or unplugging a device with the mic channel 'open' - the resulting 'pop' through the speakers could write off a delicate tweeter.

Otherwise, there should be no issues because of the original design brief as mentioned by Anahata.

However, if a desk (or add-on phantom power PSU such as an old AKG N66E we have here at work for mixers not having phantom) has been poorly designed, plugging in an unbalanced device (XLR pins 1 & 3 strapped) could cause phantom to be shorted out.

We used to have some Sennheiser 'Black Fire' VHF radio mic receivers (BF1051 and BF1052 kits - really they were Chaiyo with a badge job!) that didn't like phantom squirted up their XLR output... they started making all sorts of frying noises after a few minutes, though no damaged ever occurred. Fortunately they also had a line out on jack, so we just had to remember to use that!

Richard's opening post suggested he had issues - they were more likely to be problems within the desk or cables than the microphones, I would suggest.

I would add that it's unusual these days to find desks with 48v phantom - 24v or even 15v is more the norm, as 'studio condensers' requiring 48v are rarely used by live musicians. Some microphones, typically AudioTechnica, require as little as 1.5v, many only need 9v, such as AKG C451, C1000 and the like.

The purpose of phantom is to apply a charge to the capacitor plate - electrets need a lot less than true condensers which do require 48v.