Question About Safety And Main Isolation Switch

[NewHomeowner]

Hello everyone - I've been on her before and got some useful replies to questions, so I hope you can help me again...

I've passed my BS7671 and have done quite a few jobs, including upgrading a CU under supervision, but I'm lacking experience in a couple of areas.

Here's my question -

A customer had asked me to provide power to a new property.  When I visited the site, the supply company hadn't yet installed the meter (which was to be mounted externally in an appropriate IP rated enclose.  The customer asked if once they had done this that I could fit a CU and supply to the property (a hardstanding).  I said I could do this in theory - ....IP rated CU fitted close to meter - routing an SWA cable, buried at appropriate depth to inside of the hardstanding to an internal CU and from there it's pretty straightforward - lighting, sockets only, etc..

BUT ... I asked that they ask the supply company to fit an isolator switch (presumably 80A - 100A) to the meter when they came to their install.

I haven't been back to the site since, but am due to go later this week.  I've come across and worked with only one type of isolator before - A 'digital' style type where the supply is cut off by turning a slot clockwise with a flathead screwdriver - and this allowed me to work perfectly well on that installation, but isn't there also a DP type 'main switch' isolator - like a big switch?  Is this the case, and can I expect this to also totally cut off the mains supply without the DNO having to be called out again to pull the main fuse? (I won't do this under any circumstances).

I'm asking because I'll have to install new tails from the isolator to the new CU and I want to be perfectly sure of my safety - that the isolator turned OFF really means off.  I'm content to test this with my Kewtech, but wanted to hear the views of you experienced guys and girls.

Thank You.

 

[Murdoch]

I think you will find that the supplier will not connect to just an isolator.

Do you have a "builders board" and a cert to cover it? and also it'll need to be a TT.

 

[steptoe]

install your switch fuse and a REC2 and the DNO will connect to that for you,

yes, a REC2 will isolate totally, unless its faulty, and Ive not yet came across one yet that has failed, but I suppose it is possible,

yes, what murdoch said,

and, you need to have done your bit BEFORE the supply is connected under normal circumstances.

 

[Murdoch]

install your switch fuse and a REC2 and the DNO will connect to that for you,

yes, a REC2 will isolate totally, unless its faulty, and Ive not yet came across one yet that has failed, but I suppose it is possible,

Unless EDF are connecting the supply and they do not allow switch fuses. I had a big arguement with them recently about this and lost!

 

[apprentice87]

WPD connected my three phase supply to just an isolator....

john..

 

[steptoe]

Unless EDF are connecting the supply and they do not allow switch fuses. I had a big arguement with them recently about this and lost!

WTF?

what do they expect you to do if your CU is >3m away?

 

[apprentice87]

HI Murdoch,

What was their reason, EDF i mean?? What did they say??

john..

 

[Murdoch]

WTF?

what do they expect you to do if your CU is >3m away?

I had to move the CU!

HI Murdoch,

What was their reason, EDF i mean?? What did they say??

john..

The EDF man said they do not allow switched fuses, they do not allow isolators, or anything else in their meter cupboard!

 

[steptoe]

I had to move the CU!

The EDF man said they do not allow switched fuses, they do not allow isolators, or anything else in their meter cupboard!

yer, I can go with that, Ive often had to install another cabinet side by side for that reason,

being allowed to install in 'their' cabinet is actually a billy bonus,

it is 'their' cabinet even though the householder has paid for it.

 

[Murdoch]

Take a read of this for starters:

http://www.ukpowernetworks.co.uk/internet/en/connections/documents/Do%20you%20need%20to%20connect%20a%20temporary%20power%20supply.pdf

 

[apprentice87]

Ah yes, in their meter box... They do have rules about that, but WPD did not mind that i had the meter box stuffed full of my stuff. They were more interested in talking about fishing and having a laugh!! You must just have been unlucky and had some p****** turn up..

john..

 

[Murdoch]

This subject of connections/temporary supplies/isolators/cutting seals and removing fuses is the BIGGEST pain in the arse for me.

The Schemes need to get together and work with the "companies" and thrash out a rUK wide agreement on policies that we can work with AND provide a single 0300 number we can call for advice and guidance.

It wouldn't be difficult but I can't see it ever happening.

 

[apprentice87]

I had to do similar forms, well, i was supposed to, but i just wrote them a very nice letter giving all the details they wanted. A VERY nice young lady read my letter, [i took it in there] and announced that it "gave the planners all the info they needed" and that was that. They gave me a price a few weeks later, i turned up, they gave me a free fibreglass box thing, loads of 4 inch ducting [like about 30 yards of it] and off i went and installed it all.

The people that came to dig the hole were PROPER numpties, as were the cable jointers, but all was sorted in the end. [i had to supervise it all, but where there is a will, they will find a way to do things wrong...]

john..

 

[ProDave]

Up here, in the northern part of SSE land, the DNO expect an "installation" with at least one tested circuit before they will make a connection.

In the case of a new build, a mini CU feeding a site power socket is enough.

On my own new build I have two meter boxes side by side, one for "their" equipment, and one for a small CU and a switch fuse, so nobody can complain about my stuff in their box.

 

[apprentice87]

That is the safest thing to do by far. I had no choice but to stick the stuff in their box, thank god they did not have a fit, would have been COMPLETELY stuck if they had!!

john...

 

[NewHomeowner]

Hi everyone - Thanks for your replies.

So are you saying, Murdoch, others ... that I'll need to supply this or similar .....

http://www.tlc-direct.co.uk/Images/Products/size_3/CGMSF100.JPG

And install it upstream to the CCU etc.... and downstream with the meter tails ready to be connected to the meter by the supply company? Ie - give them a shout when I'm done?

Thanks

 

[Murdoch]

Hi everyone - Thanks for your replies.

So are you saying, Murdoch, others ... that I'll need to supply this or similar .....

http://www.tlc-direct.co.uk/Images/Products/size_3/CGMSF100.JPG

And install it upstream to the CCU etc.... and downstream with the meter tails ready to be connected to the meter by the supply company? Ie - give them a shout when I'm done?

Thanks

That, a CU, with TT rod and EIC - they should provide the tails from the meter

 

[NewHomeowner]

Got it.

Thanks Murdoch - Got the CU, but naively thought the DNO would supply the isolator switch as they did to a previous existing supply I was working on. My mistake.

Thank you.

Think I'll refer the customer to a more experienced sparky. I'm content installing the CU, all the upstream stuff and the Switch fuse, and though I know the theory, I've not installed or tested a TT system before.

Thanks everyone.

 

[apprentice87]

[SIZE=11pt]Hi all,[/SIZE]

[SIZE=11pt]"For the avoidance of doubt, where customers’ installations at the time of requested connection comprise a very limited extent of electrical lines and plant that has been demonstrated through tests and certificates to comply with British Standard Requirements, then connection of the electrical installation should be made. For example, where a customer’s initial installation comprises a double pole isolator with meter tails ready for connection to a metering system and a customer earth block with conductor ready for connection to a PME terminal and the customer’s installation complies with British Standard Requirements then connection should not be refused[/SIZE]"

This is from the instructions to the morons that connect meters..... If you just present them with a REC2 and a MET, they must connect it for you...

john...

 

[NewHomeowner]

Ok - The supply company DID supply an isolator switch, so I could work safely.  I  installed the tails from the isolator to the CCU and carried out all of the work downstream of the supply.  Except for one thing.  I don't know if this is a numpty question, so apologies in advance. 

Now, the image above is not of the installation I've done, it's a generic image from the net.  Have a look at the Earth connection going into the right hand side of the main fuse.  My problem is exactly this - the main fuse in my install is exactly this 'style'.  I can open up the 'rose' in the front of the fuse, and loosen the four screws which I guess hold the earth plate securely in place, but there is no obvious 'knockout' or similar for me to route the earth cable through on the right hand side - there's little space, so I can't easily see, but to me it seems there is just the solid plastic casing.  As this is the main fuse, I certainly don't want to attempt to drill a hole in it and shatter it.

So my question is this - should I call the Electricy Supply Company and ask them to call out?  Or does anyone think I can safely attempt to create an access in the right hand side of the casing?

Thanks in advance.

Steve