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db/cu and 521.5.1 Ferromagnetic enclosures: electromagnetic effects

psychicwarrior

a good day wishes to all

 

‘they’ do not write these things for no reason; there is science present, so …

using this example: what's the non-compliance issue, if any in reality, with meter tails entering a db/cu through the same opening (fair enough), but a main earthing conductor being glanded/bolted to the housing inside (via a different aperture to the tails, to the earthbar attached to the case, along with bonding etc),  or even on the outside  ?   

 

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    I recon that the line and neutral conductors should enter by the same hole in a ferrous enclosure to reduce the chance of heating of the cables or enclosure, but tests have proved that the heating effect of a single conductor carrying a fairly large current has a very small heating effect. Mike points out that the metal is quite thin and the heating effect is quite small if we look at it as an A.C. magnetic field cutting a ferrous conductor as in a transformer effect. Normally the earthing conductor will not carry a heavy enough current to produce any dangerous damaging heat.

     

    Z.

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  • 0

    I recon that the line and neutral conductors should enter by the same hole in a ferrous enclosure to reduce the chance of heating of the cables or enclosure, but tests have proved that the heating effect of a single conductor carrying a fairly large current has a very small heating effect. Mike points out that the metal is quite thin and the heating effect is quite small if we look at it as an A.C. magnetic field cutting a ferrous conductor as in a transformer effect. Normally the earthing conductor will not carry a heavy enough current to produce any dangerous damaging heat.

     

    Z.

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