old CU, bad earth, fused neutral (photo) advice

[plugwash]

or like my parents a diyer rewired it and either didn't feel comfortable changing the CU or didn't see any need to do so.

for years our house had modern wiring connected to a brown bakalite wylex with 2x5A and 4x15A rewirables.

 

[kai]

This setup shows a good solution - a PME-TNCS earth, (You can just about see the main earth emerge from the right hand side of the Service Fuse Holder Block) and an 125amp Industrial Isolator used as the Main Switch for the whole house.

 

[aspeakman]

Kai - that is some serious installation. Is it not overkill to use an industrial isolator? -It probably cost more than the CU itself.

Why are the fridge and freezer on their own individual MCBs? Is it just so that if a trip occurs somewhere on the ring main, the fridge and freezer continue to operate?

I have heard that HiFi and computer equipment is sometimes kept separate from the normal ring, but in a normal house I can't see that being practical.

 

[Steve]

I can see problems arising when the DNO come and upgrade that meter . . . seeing as new meters are slightly wider than old ones IIRC . . .

 

[kai]

Actually the Industrial Isolator cost 20 Pounds from Screwfix, and the din-rail box cost 15 pounds from Hagermeyer, so 35 pounds in total.

Perfectly safe, as the industrial isolator can more than cope with the whole house's curent demand - it's rated at 125amps AC22A duty.

The Fridge and Freezer run off their own breakers, and own main switch, so a trip elsewhere down not ruin any food etc.

 

[Invisible-Man]

This setup shows a good solution - a PME-TNCS earth, (You can just about see the main earth emerge from the right hand side of the Service Fuse Holder Block) and an 125amp Industrial Isolator used as the Main Switch for the whole house.

Hi Kai, I would like to copy your Industrial isolator idea, I have seen the 125amp double pole isolator at screwfix, Ist question, what enclosure did you use, and secondly, it looks as though you have 2 pairs of tails coming out which is what I would need, (1 for consumer, 1 for sub-supply) how would this be wired within the 4 pole isolator!

Many thanks,

 

[aspeakman]

thanks Kai, that looks like a 4 pole isolator, are you just using two of the poles, or have you paired them? To save space I might just go with a 100A DP and a smaller enclosure, as in JohnD's pics

 

[Adam_151]

I think I remember him saying he used a 3ph + n isolator so that he had two spare poles for if he ever installed storage heating that he could run those tails through it as well, while a pretty good way of doing things if storage heating is installed, I feel he might be future proofing a tad too much....

 

[JohnD]

I think the 4-pole isolator, linked 2+2, is neater than the more common 2P isolator plus Henleys.

 

[aspeakman]

I take it the henley connectors would be required to allow two pairs of tails / CUs to be connected to the main isolator?

 

[JohnD]

That's right. You can get them to take 5 sets. Many installations have 2 CUs (one main, and one added later e.g. for an electric shower or a garage supply). This is the arrangement in th einstallation on my photo on the previous page; though the pic is too dark to see it clearly.

I like to start off with a good big CU with plenty of room for future expansion, it saves such untidiness.

 

[Invisible-Man]

I think the 4-pole isolator, linked 2+2, is neater than the more common 2P isolator plus Henleys.

This is my point John, I would not have fitted an isolator, but as I am faced with splitting the tails for a sub-supply thought that this would make a neater job, I think that kai already has 2 pairs of tails coming from the isolator, I was asking him if perhaps Wylex supply a conversion for the 4 pole isolator to use as a single phase on the input/supply side!

 

[JohnD]

I don't think Wylex make that kind of thing, it is more industrial.

MEM make a converter for people who want to use a 3-phase Distribution Board on a single-phase supply. It is just a short copper busbar that slots into the terminals. The converter I'm thinking of links three poles tgether; but you could use two, and cut the third tooth off each.

I expect other makers of Industrial and Commercial devices have an equivalent. There may even be a 2-way link as standard.

 

[Invisible-Man]

I don't think Wylex make that kind of thing, it is more industrial.

MEM make a converter for people who want to use a 3-phase Distribution Board on a single-phase supply. It is just a short copper busbar that slots into the terminals. The converter I'm thinking of links three poles tgether; but you could use two, and cut the third tooth off each.

I expect other makers of Industrial and Commercial devices have an equivalent. There may even be a 2-way link as standard.

I beleive kai said he got it from Screwfix, I think it must be this one

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331833&ts=21030&id=21122

 

[JohnD]

I think you're right they also have a converter
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331833&ts=23737&id=29206
though it's not the same as I had in mind.

I don't think I've ever come across a Wylex TPN DB.