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Discuss 60A Fuse box - is (typical) over 60A max load OK? in the Electrical Forum area at ElectriciansForums.net

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This relates to one of those old 60A Wylex Fuse boxes that has been upgraded with MCBs - I know it would be a very good idea to upgrade, but the question is, how does the "Max 60A" rating moulded on the box apply? The main fuse is 60A and the load after diversity calcs is 89A.
I am aware that this is not an unusual load for a typical house with a 60A main fuse (which can safely maintain higher loads for a relatively long period as per the time/current graph), but less clear how it applies to the fuse box & whether a 60A Fuse box was typically intended to be paired with loads suitable for a 60A main fuse. Is this limit in fact a further limiting factor on the overall load, due to things like temperature limits on the components in the fuse box, or maybe how well the main switch can cope with arcing (if say somebody tried to throw it at full load).
i.e. Diversity figures should be strictly applied in this scenario (in spite of that making the box unsuitable for most typical homes)?
 
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Baddegg

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89A after! Can’t be more than 6-8 ways on the board surely? What was ya total before diversity?
 

Wilko

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Hi - I think The Book answer is the board was certified as safe for 60A load. The main fuse is there to protect the supply cable and should not be relied upon to protect the board. Practically speaking, with 60A fuse and sensible domestic loads it will probably outlast us all.
 
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To try & respond to some of the replies:
There are 7 circuits +1 spare
Upstairs + Downstairs lights & sockets =4
Kitchen ring
Immersion Radial
Cooker Radial
Main loads are 20A cooker, 31.3A hob, 13A Immersion heater
For practical diversity calcs I treated the kitchen ring as part of the downstairs ring.
So not really unusual at all.
I have no specific rating for the main switch, the 60A Max rating is moulded along the bottom in the plastic, so I think applies to the unit as a whole.
I accept the point made about the main fuse, but it's not directly relevant to the question.
I don't think anybody really answered the question except possibly Wilko, although the question really was, what does that 60A certification mean in practice (e.g. overheating) and given that 60A fuses were typical when these boards were sold, was there likely any co-relation that the manufacturer intended these boards to service loads that would be typical with such a fuse & I make the contention that this is a fairly typical load.
Presumably also Wylex would have allowed some margin.
 
That switch complied to BS5419, superseded by EN60947-3. These standards require/required a switch to carry its rated current and be able to be switched whilst carrying this current. The standards also allow for overcurrent but not necessarily short circuit or fault current.
 
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