30 Amps DP mains supply concern

[Thirst]

Note: I am not an electrician.

I have a large house that has been divided into 4 flats with an additional landlord supply, so 5 meters in total (2 smart meters, 3 dump meters). I recently noticed that there was damage to one of the supply side fuses. I called UK Power Networks who came and taped it up to temporarily 'make safe'. In doing do engineer made clear his surprise the property was being fed by a single phase cable and that really we should be on three phase. We've never blown the supply fuse and the cost of upgrading ain't cheap so for now we've decided a 'do nothing' approach is appropriate unless we hit problems, especially given appliances are becoming more efficient with time. I believe the supply fuse was 100Amp. UK power networks are however insisting on a section cut out to install a new supplier fuse - in doing so they will need to cut power to the property. Will they always replace like-for-like in terms of Amps?

Now my main question is:
Each of the 4 flats currently have 30Amp DP isolator switches next to the meters. Not only are they ancient, I'm concerned at the 30Amp ratings on them. Whose responsibility is this? Should the smart meter installers have picked up on them and suggested they be replaced first? Could I ask UK power networks to replace if I supplied new 100Amp DP switches? Are they likely to allow these to be replaced whilst they are doing the section cut out?

Help and advice please?

 

[Midwest]

The question would be is what the load is, in each flat. What are you providing for your tenants?

The 30A isolators are just that, they isolate things, and do not provide any fusing.

 

[Thirst]

My concern is that the draw may exceed their 30amp rating and therefore become a fire risk. Each of the flats have washing machines, 2 of them have electric hobs and another is soon to replace their hob and oven with electric and install a dishwasher. Add in 4 toasters, kettles, TVs etc. Unlikely they would all ever be on at the same time but it is a possibility.

 

[westward10]

The question would be is what the load is, in each flat. What are you providing for your tenants?

The 30A isolators are just that, they isolate things, and do not provide any fusing.

Those isolators contain fuses.

 

[Midwest]

My concern is that the draw may exceed their 30amp rating and therefore become a fire risk. Each of the flats have washing machines, 2 of them have electric hobs and another is soon to replace their hob and oven with electric and install a dishwasher. Add in 4 toasters, kettles, TVs etc. Unlikely they would all ever be on at the same time but it is a possibility.

I think you need to employ a competent electrician to come and inspect your installation. What supply does each flat have, and what sort of consumer units do they have fitted?

 

[Midwest]

Those isolators contain fuses.

Oopps missed that, I thought that pic was some advertising, which is crammed onto my screen page, all too common now.

Looking at that, I feel more inclined to call out a sparks, not pass go & go directly to jail.

 

[Thirst]

Fair enough advice guys. Should any spark be able to deal with this or should I be looking for one with a particular accreditation when it comes to stuff that directly touches the supplier side?

 

[Midwest]

Your 'main supply' is the responsibility of your Distribution Network Supplier, metering your energy supplier. The supply to each flat would normally be the responsibility of the builder owner; do your tenants have energy supply meters in their flats (and who owns them)?

A new installation, would have all the meters located in a central point or cupboard.

This is for a normal dwelling;



Items 1-7, would be inside the cupboard, along with an appropriate switch fuse, for the ongoing distribution circuit to each of your flats.

 

[mhar]

Can you show a picture of the top of the cutout (big black thing the supply cable goes into)? There look to be a number of red / brown cables emerging from it which would be an ESQCR issue if it really is single phase.

 

[Octopus]

What load is there on the communal circuits?

 

[Thirst]

Load on the communal circuits is minimal. Couple of smoke alarms, 4 LED lights and a plug socket that occasionally has a lawn mower plugged in once a month.

Attached is a photo showing the top of the unit. I suspect those new brown cables were installed by the smart meter providers. I remember one of them pointing out they upgraded the tails. Guessing the UK Power Networks need to change the remainder to match now?

 

[Midwest]

Think the DNO engineer was commenting, that their supply cables was 100A single phase, albeit the load side seems 3 phase (and head)?

 

[Thirst]

Are you saying you suspect the main supply from the road is 3 phase but the output from the supply fuse to the meters is single phase? Therefore an upgrade would require all 3 phases be connected from the new fuse supply to new 3 phase meters but nor require a new cable fun from the road?

If so, does this really provide a tangible benefit? Should I bother looking to upgrade the meters etc?

 

[mhar]

The colour is not relevant (red or brown doesn't matter). Having two meters from a single phase cutout isn't done now but used to be. You appear to have 4 if the supply really is single phase. The only way an electrician would be able to tell is to measure voltages between the lives in the isolators. If it is single phase then it comes under ESQCR and the suppliers / dno need to sort it out, I would be looking to get this free of charge as you have acted in good faith, it appears to be the suppliers / meter fitters in the wrong

 

[Midwest]

Are you saying you suspect the main supply from the road is 3 phase but the output from the supply fuse to the meters is single phase?

Nope, think your DNO was saying the opposite.

 

[Thirst]

mhar that is very interesting. Are you suggesting that it may be for the DNO to do a new 3 phase cable run to the property because the current setup falls foul of ESQCR? What exactly would the suppliers (5 different ones might I add) be expected to provide/change/upgrade in this case?

Should I ring UK Power Networks and ask them to confirm in writing whether the current supply is 2 or 3 phase as a first step?

Right now this whole setup sounds rather dodgy.

 

[mhar]

Yes re confirmation letter

 

[Midwest]

I'd expect they'll want you to pay for whatever you'll doing in your property, I don't know.

You have one house thats been (at some point) converted into 4 separate houses. Looks like (at some point) it had a 3 phase supply, thats now single phase supply. What occurred first, then subsequently changed is the question.

 

[dmxtothemax]

5 units = 100A service
100 / 5 = 20A.
So 20A is readily available for each
With 30A surge capacity.
I think this is just enough, you have had no problems yet.
As your fuses are correctly choosen to protect the system ?
Then you have no worries.
Ideally twice this capacity would be ideal,
But all this upgrade will have to be paid for by someone
If they are willing, go for it,
If not, I would not worry too much.
Does the land lord understand that his electrical
system is limited and maxed out ?

 

[Thirst]

Ok, so I spoke to a very helpful woman from UK Power Networks who use to do installations herself for 8 years. Going by photos she believes that there is 3 phase power coming into the property as we have a 3 phase cutout, however only 2 phases are being used. She also suspects the current fuse will be 80Amp and not 100Amp.

She suggested that I:
1) Get one of the MOPS to confirm 3 phase supply
2) If confirmed, contact UK Power Networks to perform replacement 3 phase cutout as current unit is damaged.
3) Have an electrician install a 3 phase ryefield distribution board.
4) Have all 5 MPOS come and re-connect to the ryefield distribution board.
5) At the same time as above replace all 4 DP isolation switches and install 5th for Landlord supply.

This means that we can then take advantage of the 3 phase supply coming into the property.

How does this sound to you guys?