Coverting to 3 phase in domestic cottage

[wearethepeople]

Hi All,

Bit of a change of direction from my recent post, In an old cottage they have a present a 3 phase cut uot supply feeding a single phase meter with one d/b.

A full rewire is needed, they are having a daikin heating system and the Max demand I have worked out is 165A.

I will obviously need to use all three phases however there is only enough room for a single phase d/b in the existing overdoor cupboard.

1. What meter am I to apply for i.e three phase economy 7/10 or normal?

2. Do I run a sub-main for the meter tails to a more suitable position for a three phase board?

3. If so what cable/isolators will I need to protect tails? (they can run under floor or I may be able to get boxing built around steel works?) run about 30m max

4. Do I divide all circuits evenly over all three phases? they are all single phase distribution circuits

Many Thanks

 

[Mr Mark Sparks]

Hi All,

Bit of a change of direction from my recent post, In an old cottage they have a present a 3 phase cut uot supply feeding a single phase meter with one d/b.

A full rewire is needed, they are having a daikin heating system and the Max demand I have worked out is 165A.

I will obviously need to use all three phases however there is only enough room for a single phase d/b in the existing overdoor cupboard.

1. What meter am I to apply for i.e three phase economy 7/10 or normal?

2. Do I run a sub-main for the meter tails to a more suitable position for a three phase board?

3. If so what cable/isolators will I need to protect tails? (they can run under floor or I may be able to get boxing built around steel works?) run about 30m max

4. Do I divide all circuits evenly over all three phases? they are all single phase distribution circuits

Many Thanks

hi mate


1 a 3 phase 2 rate meter and then sort tarriff with supplier
2 yes thats the best idea
3 as a guide 25mm meter tails to 100a sw fues then 25mm 4core swa with sep 16mm cpc to new possition
4 yes you need to balance the load evenly

 

[wearethepeople]

Cheers Mark,

What do you think the best way to go about routing the 25mm 4 core swa and 16mm earth, the distance could be about 20m max, I know it's hard to say but this play is empty but real old nice floorboards that they don't want damaged, although they are ahvingg steels put in on 1st floor, could I make use of these or can you recommend better way? and also why only 100A switch fuse out of curiousity? I'v worked out max demand as 160A hence the upgrade to three phase.

The joists are really tight prob 100mm depth.

Cheers again

Ian

 

[Mr Mark Sparks]

100a sw fuse 100a per phase your 160a is total i would of thought not times 3
is this correct?

the run of the cable is up to you i cant really help having not seen it but swa can go anywhere

 

[wearethepeople]

Ah of course there's 3 x 100A fuses in the switch fuse am I correct!?

Yes 160A total, geez thats going to be tight for the switch fuse alone in the overhead cupboard.

Thanks again

Hi Mark

Would a 100A MEM TPN Exel 2 Switchfuse do the job!? Also on a TT system how Would I protect the tails from the meter to this switch fuse!?

Thanks in advance

 

[Mr Mark Sparks]

maybe better to fit a 4pole 100a 100ma rcd in an enclosure instead being tt
then the swa is protected

 

[wearethepeople]

Can you recommend the enclosure i'm just tryin to work out the size and if I can get the TT converted to pme just a standard 4 pole iso as said before would do!?

Cheers

 

[dragon-av]

I'm no specialist but why not ask for new meter location and new supply from LEB to a better location for the distribution board. As its a full upgrade and complete rewire seem logical to just start agin away from the door location over to utility room/closet

 

[wearethepeople]

I can definetly put that to the clients not sure of the pricing however.

Thanks

Do you think all propertys that now now have a 60A electric boiler/40A cooker couple of rings and lights need a threephase supply!?

 

[dragon-av]

With a 60A boiler loads and LEBs being unwilling to allow more than 100A connections i think it does! I do have a custome who cant get 3 pahse so is getting a twin supply! Three phase board with 2 legs connected

 

[aptsys]

Would a 100A MEM TPN Exel 2 Switchfuse do the job!? Also on a TT system how Would I protect the tails from the meter to this switch fuse!?

No. On a TT system, you cannot have a metal clad box before the RCD.

 

[Spudnik]

Relocating a three phase incomer could be very expensive.

 

[dragon-av]

Relocating a three phase incomer could be very expensive.

Bit if the current incomer is single phase they will have to do most of the stuff to put in three phase so it would seem logical to me to move the incoming location at the same time.

 

[boatnik1]

Bit if the current incomer is single phase they will have to do most of the stuff to put in three phase so it would seem logical to me to move the incoming location at the same time.

My reading of the situation is that the incomer is 3p not 1p.

 

[dragon-av]

Hi All,

Bit of a change of direction from my recent post, In an old cottage they have a present a 3 phase cut uot supply feeding a single phase meter with one d/b.

Indeed it is Ooops never mind still seems most obvious to move it as i doubt the client is happy about the current location and i thoguht all Boards wanted acccessible meters these days, ie external acces.

My reading of the situation is that the incomer is 3p not 1p.