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Old incomer connected to four 3 phase cutouts help

Simon M
Hi all,


I have a very old incomer entering the building that then feeds to 4 x 3ph cutouts. You can see two of the 3ph cutouts in the pic.
9f8642aebed8db60e40f7a2578ffd3a3-original-02.jpg


The incomer says on it  - BI Callender's - 4E 150 x 3. I assume this means 3 x 150 Amps? Please do correct me if I am wrong.


1. What is the maximum power I can draw from this system?


2. If each of the 4 Three phase cutouts were loaded with 100 Amp fuses and I was to pull close to that from each fuse. what would happen to the incomer as this would equate to 1200 Amps!


3. Is connecting 4 3ph cutouts to this old beast a reasonable thing to do? Or is it ridiculous?


Many thanks

Simon
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    If each of the 4 Three phase cutouts were loaded with 100 Amp fuses and I was to pull close to that from each fuse. what would happen to the incomer as this would equate to 1200 Amps!

    Nah, just 400A/phase. Even at 40% diversity (DNOs usually use a lot less) it's not much above 150A. I suspect the original cut-out is fused, so if you did keep up a 400A load for many many hours, you might blow them.


    Presumably it's feeding multiple domestics premises (flats?) - in which case unless the primary space heating is entirely electric (e.g. storage heaters), I doubt it would even get warm.


       - Andy.
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    If each of the 4 Three phase cutouts were loaded with 100 Amp fuses and I was to pull close to that from each fuse. what would happen to the incomer as this would equate to 1200 Amps!

    Nah, just 400A/phase. Even at 40% diversity (DNOs usually use a lot less) it's not much above 150A. I suspect the original cut-out is fused, so if you did keep up a 400A load for many many hours, you might blow them.


    Presumably it's feeding multiple domestics premises (flats?) - in which case unless the primary space heating is entirely electric (e.g. storage heaters), I doubt it would even get warm.


       - Andy.
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