1c31762d   
   From: 6df275e545df745c93031912e6817ff2@example.com   
      
   > TraHello friends   
   We are active in the field of pipe thermal elements.   
   thank you   
   cking that results in permanent damage is caused by the insulating material   
   breaking down and forming a conductor (or at least a partial conductor), such   
   as plastics breaking down and leaving a carbon track. Magnesium Oxide will not   
   breakdown, so you    
   shouldn't be able to damage it any further by turning it on. If there was lots   
   of moisture in there, you might get an arc right across that would leave   
   vaporised metal, but the heater has had it by that point anyway (the magnesium   
   oxide should be under    
   enough pressure to quench any such arc unless the case is burst).   
   > I don't have the PAT test guidelines to hand at the moment, but they used to   
   allow you to operate mineral insulated heaters to drive off condensation   
   before performing the insulation test. I just can't recall if that's still in   
   the current version of    
   the IEEE in-service inspection and testing document.   
   > Obviously, it's important to check the casing is properly earthed. If   
   there's an RCD in the circuit, that may prevent you operating the heater to   
   dry it, but if it's leaking somewhere over 15mA (as may trip a 30mA RCD), then   
   it's probably got too much    
   water in to be considered still OK.   
   > I would also say if you have an earth leakage and are contemplating leaving   
   the heater in service, you should inspect the surface for damage, as the usual   
   cause nowadays is that a hot-spot has formed and punctured the case, so it may   
   not last much    
   longer anyway. Given that you have to take the heater out to   
      
   --   
   For full context, visit https://www.polytechforum.com/electrical   
   moisture-in-magnesium-oxide-insulator-73886-.htm   
      
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