Main MCBs replacing incommer switches

[John-SJW]

In this Youtube vid it shows an electrical CU on the French/Italian border. One comment says it was done to Italians ways. One comment say it is normal to have 30A supplies, as was this. They install 30A DP MCBs as the main incommer switch, so as not to blow the main fuse. Sounds a good idea. Maybe something we should do as standard.

 

[pc1966]

In this Youtube vid it shows an electrical CU on the French/Italian border. One comment says it was done to Italians ways. One comment say it is normal to have 30A supplies, as was this. They install 30A DP MCBs as the main incommer switch, so as not to blow the main fuse. Sounds a good idea. Maybe something we should do as standard.

I believe the ROI now mandates that, a DP 63A MCB as the incoming switch.

Makes a lot of sense to me, but also restricts the CU total a bit (which I guess is the whole idea).

 

[John-SJW]

I believe the ROI now mandates that, a DP 63A MCB as the incoming switch.

Makes a lot of sense to me, but also restricts the CU total a bit (which I guess is the whole idea).

ROI? Return on Investment?

 

[littlespark]

Republic Of Ireland, John…

Some more words…. La la la

 

[John-SJW]

Oh! Now I know. What is the standard size of main fuse there? 60A? Many 100A?

 

[pc1966]

Oh! Now I know. What is the standard size of main fuse there? 60A? Many 100A?

No idea, probably @Risteard or @LastManOnline would know.

They would need to be something like 80A for any selectivity with a 63A B-curve and 100A for 63A C-curve though, but if only overload concern (not high current fault) then maybe a 63D curve and 100A would be possible.

I'm considering typical BS88 fuses, not sure if the same sort of characteristic is used in ROI as I think they used to have the diazed style fuses more common in EU.

 

[John-SJW]

A main incommer MCB need only be for overload protection not fault. A string of RCBOs can cope with other issues.

 

[pc1966]

A main incommer MCB need only be for overload protection not fault. A string of RCBOs can cope with other issues.

True, but looking at the curves using Schneider's on-line tool and 63A B with 80A is not guarenteed selectivity even ar overload values (i.e. inside the thermal trip part).

 

[pc1966]

The results from that tool:

 

[pc1966]

Schneider's site is rubbish, brakes in silent way with ad blocker in spite of not having any adverts! Also gibberish URL, but link from here is easier route to finding it:

Country Selector | Schneider Electric Global

Country Selector Page

www.se.com

 

[Risteard]

No idea, probably @Risteard or @LastManOnline would know.

They would need to be something like 80A for any selectivity with a 63A B-curve and 100A for 63A C-curve though, but if only overload concern (not high current fault) then maybe a 63D curve and 100A would be possible.

I'm considering typical BS88 fuses, not sure if the same sort of characteristic is used in ROI as I think they used to have the diazed style fuses more common in EU.

A 12kVA (Standard) supply has a 63A main overcurrent device, and a 16kVA (Enhanced) supply has an 80A main overcurrent device.