Dyslexicbloke
Member
Hi folks,
I have a hydro customer who also owns a fish farm. Currently, he has 3 entirely separate TN-CS supplies, the hydro which is 3 phase and fine, the fish farm which is nasty and single phase and the house and workshop, also single phase, which is marginally better but not good in many respects.
The plan is, at the moment, to ditch fish farm and house supplies and put everything on the hydro.
I am aware that this will require distribution upgrades because both systems will essentially be new installations when reconnected, at least I am assuming that would be the case, and we will likely use a local electrical contractor to do the work, once it is specked.
Distribution to what will considered sub boards now is organised and we have speced RCD protection for both cables. We have had to use adjustable MCCB's to get disconnection time right but the design look good... Not that anyone has signed off on it yet.
However The customer is now talking about keeping the existing domestic supply as a backup and wants a changeover switch...
This presents some issues to say the least.
The connection heads are about 160m apart which means we cant link P-N at that location as iot is well inside the installation.
However to use the existing TN-CS connection at that point we would of course be doing exactly that because the link is in the DNO head.
My first thought was a 5 pole changeover so that the P&N are handled separately. I dint have a copy of the 18th/2 right now and although I know that PE switching can be done I suspect the regs will have some pretty stiff requirements for implementing that. I encounter switched P-N links quite a bit as I work on hydro systems that are essentially operating islanded when starting up but I don't think I have ever seen The source of the PE switched.
Comments would be welcome but 63A 5 or 6 pole changeover switches seem to be a rare beast, at least if we want a 'real' one' which of course is not negotiable.
That raises the question... Could we put the entire house on a plug? Yes I know, but 63A 5 pin plugs will accept a 16mm SY and if both supplies were brought to interlocked socket isolators it wouldn't be possible to connect or disconnect under load and the separation of both P & N of both systems would be total and guaranteed.
Please note this post is here because I recognise this is a tad unusual and have no realistic way to check if it is even a valid approach, let alone dig into the detail.
Any and all comments will be very much appreciated.
Thanks for looking,
Al
I have a hydro customer who also owns a fish farm. Currently, he has 3 entirely separate TN-CS supplies, the hydro which is 3 phase and fine, the fish farm which is nasty and single phase and the house and workshop, also single phase, which is marginally better but not good in many respects.
The plan is, at the moment, to ditch fish farm and house supplies and put everything on the hydro.
I am aware that this will require distribution upgrades because both systems will essentially be new installations when reconnected, at least I am assuming that would be the case, and we will likely use a local electrical contractor to do the work, once it is specked.
Distribution to what will considered sub boards now is organised and we have speced RCD protection for both cables. We have had to use adjustable MCCB's to get disconnection time right but the design look good... Not that anyone has signed off on it yet.
However The customer is now talking about keeping the existing domestic supply as a backup and wants a changeover switch...
This presents some issues to say the least.
The connection heads are about 160m apart which means we cant link P-N at that location as iot is well inside the installation.
However to use the existing TN-CS connection at that point we would of course be doing exactly that because the link is in the DNO head.
My first thought was a 5 pole changeover so that the P&N are handled separately. I dint have a copy of the 18th/2 right now and although I know that PE switching can be done I suspect the regs will have some pretty stiff requirements for implementing that. I encounter switched P-N links quite a bit as I work on hydro systems that are essentially operating islanded when starting up but I don't think I have ever seen The source of the PE switched.
Comments would be welcome but 63A 5 or 6 pole changeover switches seem to be a rare beast, at least if we want a 'real' one' which of course is not negotiable.
That raises the question... Could we put the entire house on a plug? Yes I know, but 63A 5 pin plugs will accept a 16mm SY and if both supplies were brought to interlocked socket isolators it wouldn't be possible to connect or disconnect under load and the separation of both P & N of both systems would be total and guaranteed.
Please note this post is here because I recognise this is a tad unusual and have no realistic way to check if it is even a valid approach, let alone dig into the detail.
Any and all comments will be very much appreciated.
Thanks for looking,
Al