Discuss Carrying out a refurb on old panel boards, worried about discrimination. in the Industrial Electrician Talk area at ElectriciansForums.net

pc1966

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You might want to check the main fuse, as that is quite a lot of sub-mains coming off 3*100A for example, so if they turn out to be 160A or more then you have an easier job.

I had a go at the Schneider on-line tool but it seems broken for me today :(

I would concentrate on getting tolerable MCB/MCCB selectivity using the short-delay aspect of the fancy MCCB, that way in most cases the selectivity falls back to incoming fuse and final MCB, and that is probably no problem.

Yes, a sub-main fault might not open the MCCB before the incoming fuse, but that is a lot less likely than some final circuit/appliance giving them grief.

If you can find out loads and the PFC & PSCC at each DB just now it would help to decide how well the whole system would work.
 
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You might want to check the main fuse, as that is quite a lot of sub-mains coming off 3*100A for example, so if they turn out to be 160A or more then you have an easier job.

I had a go at the Schneider on-line tool but it seems broken for me today :(

I would concentrate on getting tolerable MCB/MCCB selectivity using the short-delay aspect of the fancy MCCB, that way in most cases the selectivity falls back to incoming fuse and final MCB, and that is probably no problem.

Yes, a sub-main fault might not open the MCCB before the incoming fuse, but that is a lot less likely than some final circuit/appliance giving them grief.

If you can find out loads and the PFC & PSCC at each DB just now it would help to decide how well the whole system would work.
Yeah, that's a good point. I will get the main fuse confirmed.

I might be able to get the loads confirmed as well.

Thanks.
 

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