3 phase factory lighting

[bal]

on street lighting circuits we had problems when running anymore than 6 no400w son t fittings if one went faulty it would take out the mcb rather than the fuse in the fitting due to the additional fault time req for fuse against mcb


ie 400wx1.8 /230v = 3.14a per fitting 5 per curcuit =15.6a each fused @ 10A the mcb trips taking them all out as nick says

Mogga, I've change the configuration to utilise C rated MCB's, also reduced the lights to 9 x 250w per contactor which would now be 3 pole. Thats 3 lights on a radial per pole of contactor. The 3 light radial 250wx1.8/230v=1.95a - 3 fittings per circuit=5.86A.

I take your point - you reckon I should up the whole supply?? ie 60amp feed, C30 MCB to 30A contactor to C10 MCB's to lights??

regards

 

[nickblake]

MCBs are designed for protecting the circuits yes they are designed to handle inrush depending on type but the contacts arent designed to switch on that load imagin the arch when contact is made changed many MCB's due to worn contacts , Square D ,Proteus , Crabtree , Merlin gerin or MEM ,

When you add all the lights together its quite a load you could you's a 32 amp switch fuse , and just de rate the fuses , noe you have reduce the quantity of lights per contactor the 25 amp is well adiquate