Schneider vigi and 3phase mcb

[brightspark2010]

Hi all just posting to see if anyone knew what is correct asked local wholesaler for a 3 phase 63amp schneider rcd they sent a 4 pole vigi and a 3 pole mcb. however at the site all other 3 phase ciruits supllied by 30ma vigis and mcbs are 4 pole switching the neutral would it be incorrect to not switch the neutral or do i require a 4 pole mcb the installation is tt?

 

[johnboy6083]

On a TT system the neutral has to be switched as its potential could be near that of the line conductor, where in a TN system, the neutral is at or near ground potential.

 

[Engineer54]

If you have a TP & N circuit then you need a 4 pole breaker and 4 pole vigi unit. The 4 pole Vigi unit has tails of the correct length to connect directly to the 4 pole MCB complete with protective cover. Never have i seen a set-up, as you have described.... Be it on a TN-S, TNC-S, or TT system.

So how are you extending the neutral tail out of the Vigi unit to reach the DB's neutral bar(s)???

 

[brightspark2010]

Not done it yet now waiting for the 4 pole mcb Iwis a bit unsure as to why they had sent the 3pole mcb to go with the 4 pole vigi i had thought it would come as 1 3 phase rcd unit then looking at the others in place it was obvious the neutral was switched for a reason just needed to know what that was. However schneider do say it is possible to join the neutral tail which is not copper bar as on old vigis to the bar if necessary.

 

[Engineer54]

I've been working with Merlin Gerin multi 9 stuff, for neigh on 30 years, i've never seen a Vigi unit with copper bars, they have always been tails, to connect to an appropriate MCB...