What are your thoughts on this 3ph domestic.

[charlie76]

The installation on the attached pic is a property with a 3-phase supply and a range of fuse boards. I am currently in training but this is a family friend and I have discussed carrying out a rewire for them once I get my papers. I intend notifying the works to BC and then getting NAPIT in to use it as an inspection site to get my competent persons sign of.

My query with this is, I was of the understanding with a 3ph supply, the consumer was obliged to balance their load amongst the 3 phases. This has recently had new fuses fitted by the DNO and as can be seen they have quite happily only connected one of the phases. If I carry out a rewire, should I design the system to utilise all three phases and leave 3 tails for connection by the DNO when complete or is this unnecessary in a domestic system due to the minimal load?

 

[charlie76]

Thanks Dave. the answer I was after.

 

[davesparks]

That's ok, it's only been said a half dozen times already in this thread.

Now, more importantly, did they say you could connect to the earth terminal in that cutout?

 

[charlie76]

That's ok, it's only been said a half dozen times already in this thread.

Now, more importantly, did they say you could connect to the earth terminal in that cutout?

It's a tns arrangement. You can't see in that photo but the existing earth is connected to the supply braid below

 

[Lucien Nunes]

Returning to the original question for a moment, the DNO are not obliged to make the three phases available, nor would they have any complaint about the lack of balancing as they have provided a single-phase supply to the customer. For all you know, there's another TP+N head next door with an SP installation on L2. If the distributor is only 3 1/2 core it's up to them to know how to balance the supplies they dish out.

There are situations in which two phases (not a two-phase supply but two of the normal three) are present, where the service cable was put in for 3-wire DC. Unlike the pic above, my head at home has two cutouts with 100A fuses in of which I only use one, because the original installation was large enough to warrant having both the outers (lines). I could request another SP supply up to 100A, but if I wanted TP they would have to dig up the road.

As to whether TP supply would make for a better installation, you haven't stated anything about the demand so we've no clues other than guessing the functions of the cables in the picture.

 

[assegayer]

only god knows how someone can walk away from an installation looking as rough as that...

 

[Midwest]

If a customer comes to me asking for a rewire, and the rest of the installation is as much of a mismatched mess as the intake appears to be then I'd not argue.

Agree with you there.

 

[Lagentium]

The OP, No! What will the demand of the new installation be?

 

[sajeel]

Guys be gentle he's still in training and has much to learn positive comments will be much better. I agree the head must be verified if it is a true three phase. Also in agreement a total load must be calculated.
I would use galvanized steel trunking and feed to either to 3 phase consumer unit or use a ryefield board to balance load and distribute if more than one consumer unit is required. But as advised by others we need a load idea to advise further.

 

[Octopus]

Guys be gentle he's still in training and has much to learn positive comments will be much better. I agree the head must be verified if it is a true three phase. Also in agreement a total load must be calculated.
I would use galvanized steel trunking and feed to either to 3 phase consumer unit or use a ryefield board to balance load and distribute if more than one consumer unit is required. But as advised by others we need a load idea to advise further.

If he's still in training why isn't he asking his boss or mentor?

 

[sajeel]

If he's still in training why isn't he asking his boss or mentor?

that is a good point but the fact he has signed up to forum is positive and he has to learn as in some point in life he will need to be independent, so I would encourage him to think alone but ask his boss or mentor before carrying out any work

 

[charlie76]

that is a good point but the fact he has signed up to forum is positive and he has to learn as in some point in life he will need to be independent, so I would encourage him to think alone but ask his boss or mentor before carrying out any work

Thanks Sajeel. Don't worry, I can take it on the chin. Its quite amusing really, I have seen this on many threads on here, you ask a question and the more experienced people spend more time criticising and trying to put people down that actually answering the question. I would expect it puts a lot of people off asking a question because you have to trawl through all the negativity to actually get to the odd reply that gives a constructive answer. Its a shame really, it almost defeats the object of having a forum for discussion.

I am a project manager in fire systems and very experienced in my field. Also having been a control systems engineer for many years I am very experienced in process industries. I am now self teaching electrical books etc and will have the odd question but it appears this forum is not the place for asking. If someone asked be a question relating to BS5839 a fire installation or a control systems related question I would gladly answer, not criticise or run them down or aggressively point out all the information they had not provided in the question. Perhaps ask them to expand on the question and point them at the information which was required.

In response to above, it will be a general domestic load, not warranting any more than a 100A supply so 3 phases would not be required. Yes it is a mess hence the rewire. Someone above (I assume experienced) stated it has PVC sheathed cables why rewire, my car has tyres but they need replacing from time to time, how do you know the condition of the cables from looking at the photo. Some other comment was why rewire, because the customer has requested a rewire. Another comment was to carry out an EICR, why? It is being rewired, would you get your car serviced before scrapping it to buy a new one? See on reflection, some of the hasty comments provided above have not been given much thought and have been about as constructive as cementing bricks with margarine.

 

[Andy78]

Thanks Sajeel. Don't worry, I can take it on the chin. Its quite amusing really, I have seen this on many threads on here, you ask a question and the more experienced people spend more time criticising and trying to put people down that actually answering the question. I would expect it puts a lot of people off asking a question because you have to trawl through all the negativity to actually get to the odd reply that gives a constructive answer. Its a shame really, it almost defeats the object of having a forum for discussion.

I am a project manager in fire systems and very experienced in my field. Also having been a control systems engineer for many years I am very experienced in process industries. I am now self teaching electrical books etc and will have the odd question but it appears this forum is not the place for asking. If someone asked be a question relating to BS5839 a fire installation or a control systems related question I would gladly answer, not criticise or run them down or aggressively point out all the information they had not provided in the question. Perhaps ask them to expand on the question and point them at the information which was required.

In response to above, it will be a general domestic load, not warranting any more than a 100A supply so 3 phases would not be required. Yes it is a mess hence the rewire. Someone above (I assume experienced) stated it has PVC sheathed cables why rewire, my car has tyres but they need replacing from time to time, how do you know the condition of the cables from looking at the photo. Some other comment was why rewire, because the customer has requested a rewire. Another comment was to carry out an EICR, why? It is being rewired, would you get your car serviced before scrapping it to buy a new one? See on reflection, some of the hasty comments provided above have not been given much thought and have been about as constructive as cementing bricks with margarine.

I'm sure you can appreciate that information regarding electrical installations should not be given out freely to just anyone, as an unsafe electrical installation has the potential to kill people. To that end it would be remiss, in a professional, moral, and possibly legal sense, of forum members to not ask questions pertinent to the original question to clarify whether the OP is of a competent nature.
Some problems can arise when the OP thinks they are not getting the answer they expected or refuse to provide any additional information that may help forum members in assisting the OP.


In relation to your confusion about an EICR, it was suggested because full testing and inspection is the only proper way to ascertain the condition of the installation and final circuits. If the customer has requested a rewire then fine, that's up to them. But to use your car analogy, getting an EICR before a rewire is like getting a full MOT and inspection done on a car before deciding whether to scrap it or not. If it only needs a few bits doing to it then it might be foolish and costly to buy a new one as a matter of course.
It was not a hasty and ill thought out comment, but your criticism of it just goes toward displaying your own ignorance.

 

[Octopus]

Another comment was to carry out an EICR,

why? It is being rewired, would you get your car serviced before scrapping it to buy a new one?

From YOUR opening post

"I am currently in training but this is a family friend and I have discussed carrying out a rewire for them once I get my papers."

Discussed is very different to going to be done.

You can't always determine the state of an installation by looking at the fuse board(s) - and whilst I agree that the photo you posted may show a mess it may not actually need a rewire!

Just saying.

 

[charlie76]

From YOUR opening post

"I am currently in training but this is a family friend and I have discussed carrying out a rewire for them once I get my papers."

Discussed is very different to going to be done.

You can't always determine the state of an installation by looking at the fuse board(s) - and whilst I agree that the photo you posted may show a mess it may not actually need a rewire!

Just saying.

Blimey, its like chatting on a forum of barristers. May I strike my question and re-phrase said statement as "I have discussed carrying out the rewire as requested by them"

 

[davesparks]

Guys be gentle he's still in training and has much to learn positive comments will be much better. I agree the head must be verified if it is a true three phase. Also in agreement a total load must be calculated.
I would use galvanized steel trunking and feed to either to 3 phase consumer unit or use a ryefield board to balance load and distribute if more than one consumer unit is required. But as advised by others we need a load idea to advise further.

What needs verifying? The head is a three phase head. The incoming supply at the suppliers terminals (outgoing side of meter) is single phase.

What you you feed from a ryefield board?

And for that matter who would pay for the completely unnecessary change to a three phase meter and the possibly increased electricity bill?