Shopping list for first fix?

[JohnW2]

Regards the shopping list, because of the distance from meter board to cu I'll need a suitable isolator. It apparently also improves the health and safety of the install process. I've a question, having seen them referred to as switch fuses, does it thus really have to be a (100amp) fuse like this:
https://www.tlc-direct.co.uk/Products/CGMSF100.html

The short answer is roughly 'yes'. Those are very nice bits of kit, and any alternatives likely to be much larger (physically). Whether they will still strictly be compliant with regulations (in terms of 'non-combustibility') after January 1st next year is not certain. MCB-based (rather than fused-based) items are not really suitable/desirable.

Kind Regards, John

 

[Taylortwocities]

The only switchfuse device on your list that is practical would be the https://www.tlc-direct.co.uk/Products/CGFS100.html
Note that this utilises a FUSE and not an MCB.

There are two parts to the practicality:
1. Using a CG fuse rather than an MCB is preferable, at the origin, as it will withstand overload currents for much longer than an MCB.
2. You are planning to terminate 4 core 25mm SWA at the switch fuse. Firstly, the enclosure needs to be able to support a large SWA gland (the other options you listed do not). Also you , or rather your electrician, will need to wrestle with chunky 25mm conductors inside the switch fuse enclosure and it will be a barsteward in the others.

Personally, I would go for something like this https://www.tlc-direct.co.uk/Products/WY110M.html

On that note. Do remember that, should you opt for Economy 7, you would need a second switch fuse for that. So there is no point in running in 4-core SWA, an off peak supply would be a separate entity, need its own length of SWA from the meter, possibly its own neutral too.

 

[JohnW2]

... Personally, I would go for something like this https://www.tlc-direct.co.uk/Products/WY110M.html

I'm not at all sure that it's the situation we're talking about here - so, talking theoretically, will one of those enormous things fit in a standard external meter cabinet, along with its other contents (or be allowed in it by DNO)?

Kind Regards, John

 

[PrenticeBoyofDerry]

Hi guys, just wondering if someone would cast an eye over this and tell me if I've left anything out? I'm after getting a rake of stuff to leave my electrician

Don't forget milk, tea, sugar and biscuits!

 

[cjard]

In terms of physical size I'm not too bothered.. The service head is on a board in the lobby and I have the luxury of being able to extend the board up the wall to accommodate larger gear. Cabinet for it is to be built later.

Bearing in mind ill need 3 of these. What advantage other than size does the wylez have over the cheaper one? My spark likes wrestling y see, bit of a gym bunny

Was hoping that a 4 core could be 2 live, 2 n and armour as earth in the situation of a future change. Or run a separate earth too. Or if the earth must be armoured,a 5 core would be cheaper and slimmer than two 3 core , ?

 

[Taylortwocities]

Even if you do the purchasing
your electrician should be doing the design and telling you what to buy. Using the steel armour as the main earth in these situations requires some careful calculations and planning.

 

[flameport]

In terms of physical size I'm not too bothered..
Bearing in mind ill need 3 of these.

Option A: Attempt to cram 3 or more cheap-o-matic Wylex efforts into the space available, together with the inevitable difficulties in terminating the various cables.

Option B: Do the job properly with the equipment designed for the purpose.

 

[JohnW2]

Option B: Do the job properly with the equipment designed for the purpose.

I'm a bit confused by that one. Why does "Provides 6 x 3 single phase" (which I take to mean 18 x 100A fuses) mean that it is only "Suitable for up to 6 flats"? On the other hand, what is meant by "L1/L2/L3 in a 2/2/2 combination" - that almost seems to imply "2 x 3 single phase" (rather than '6 x 3') fuses/supplies (the 'for illustration only' photo seems to show provision for 12, not 6 or 18, fuses - so that doesn't help!)? Does one expect to change the fuses live, or does one have to precede that with an TPN isolator that would presumably kill the supply to (I imagine) 18 flats? Why does a box containing 18 fuse holders, an earth block and (although not mentioned, I presume) some sort of neutral block/bar cost £756?

Kind Regards, John

 

[flameport]

Why does "Provides 6 x 3 single phase" (which I take to mean 18 x 100A fuses) mean that it is only "Suitable for up to 6 flats"?
On the other hand, what is meant by "L1/L2/L3 in a 2/2/2 combination"

That website has a strange way of describing it, but that particular model has 6 single phase circuits divided across 3 phases. 2 circuits on each phase.

Does one expect to change the fuses live, or does one have to precede that with an TPN isolator that would presumably kill the supply to (I imagine) 18 flats?

Supplier cutout -- Ryefield board -- circuits to individual dwellings.
Metering usually after the Ryefield, one for each dwelling.
Isolation for each dwelling is achieved by removing the fuse.
The assembly as a whole would be installed, outgoing circuits connected, and then connected to the supplier cutout.

Why does a box containing 18 fuse holders, an earth block and (although not mentioned, I presume) some sort of neutral block/bar cost £756?

That is the 6 way unit, the 18 way is £1300.
Prices due to them not being mass produced items and they are built to a specification rather than down to a price.

However 6 of those metalclad Wylex things would be £500 and connecting them to the supply would inevitably require a quantity of additional connector blocks etc.
If the incoming supply is larger than 100A then the Wylex items and connectors are of no use as the cables won't fit into them.

 

[JohnW2]

That website has a strange way of describing it, but that particular model has 6 single phase circuits divided across 3 phases. 2 circuits on each phase.

I see. Thanks. I'm not sure that I can blame myself for not being sure (and for guessing a meaning which wasn't correct!)! Is that photo of the 6-way unit. If so, what are the other three fuses - on the incomer (and, if so, why?).

Supplier cutout -- Ryefield board -- circuits to individual dwellings. Metering usually after the Ryefield, one for each dwelling.

Fair enough. Do I take it that the board has no isolator?

Isolation for each dwelling is achieved by removing the fuse.

So, as I suggested, 'live'?

The assembly as a whole would be installed, outgoing circuits connected, and then connected to the supplier cutout.

That's at the initial installation. A subsequent need to isolate would presumably have to be by pulling fuses?

That is the 6 way unit, the 18 way is £1300. Prices due to them not being mass produced items and they are built to a specification rather than down to a price.

Maybe 'built to a spec', but presumably out of standard components. I would have thought that it would have been a 15/30 minute job (if that) to populate even an 18-way one with standard components, wouldn't it? What do these 'assemblers' get paid, I wonder?

Kind Regards, John

 

[cjard]

And after all that, the meter company (EOn) installed their own isolators, that looked like these
http://www.ebay.co.uk/itm/161712023370

I asked the guy what would have happened if I'd already bought a Wylex 110 and he said that he'd have ignored it, having been to a past job and found such a switchfuse already fitted, then wired the meter to the switchfuse. Later where job was audited he was hauled back, *******ed and told to fit an isolator. His argument that the site already had one went nowhere, so now he fitse what the office tell him to regardless of the sensibility

I've got to get something My spark can attach an SWA gland to now - any compact options? Re house the isolator in a small metal enclosure?

 

[Iggifer]

That is not a switch fuse, it's just an isolator, if your tails are still going to be over 3m, you still need an switch-fuse.

 

[JohnW2]

That is not a switch fuse, it's just an isolator, if your tails are still going to be over 3m, you still need an isolator.

A little editing required, I think - unless I've misunderstood your intended meaning!

Kind Regards, John

 

[Iggifer]

That is not a switch fuse, it's just an isolator, if your tails are still going to be over 3m, you still need an isolator.

A little editing required, I think - unless I've misunderstood your intended meaning!

Kind Regards, John

You're quite right. Fixed it.

 

[cjard]

Ah, my conversation with the utility spark had left me under the impression the device he fitted had an innate ability to disconnect in an overload situation..

I'll get a picture of it incase I didn't link to the right thing