100A DP Isolator Installation Between Meter and CU

[jaydub]

Hi guys,

When installing a new CU does anyone ever install a 100A double pole isolator switch between the meter and the consumer unit?

Very often I come across 16mm tails which need to be upgraded to 25mm so I join the old tails to new in a Henley block and get the DNO to come and upgrade their side at their convenience.

Instead of using a henley block could I use an isolator instead?

In anyones opinion would there be any disadvantages to this?

I wouldhave thought having an isolator would be very handy but the meter guys hardly ever bother putting one in, even now.

They're also relatively inexpensive. Another thing, I cannot seem to finda 2-module metal enclosure so would this would be okay in a plastic enclosure? That to me seems like a bit of grey area.

Any help appreciated. Thanks

 

[Midwest]

Ok already, similar switchgear assemblies. Ring em or email em and put us all out of our miseries.

Edit; did have you with the metal thing though

 

[Spiderrico]

Unless you are working directly for a DNO a normal spark shouldn't be going anywhere near the meter to install said isolator in the first instance. You wouldn't be able to seal the meter as you don't have the sealing pliers and is illegal to do so.

DNO's charge in the region of £150 per switch so they don't like losing that earner.

All dp switches installed by Scottish Power are the wylex plastic ones. They don't work under 7671 so the fire problem isn't a consideration. In any event, if you consider most meters are housed in plastic it's kind of a pointless exercise changing to metal.

 

[alasdairp]

Three years ago I rewired my cottage in Scotland and ran the tails to an internal wooden meter board in a wooden cupboard and terminated them in a plastic covered Wylex 100A DP switch for Scottish Power to connect to. I also dug the trenches for them to run the supply which was being u/g as the wooden pole it had run to o/h was being removed for an extension. They laid the new u/g cabling, installed the 100A fused cable-head termination box and meter and then replaced my DP switch in the same position with an absolutely mechanically identical one. I asked why and they said that it had to be printed labelled "Property of Scottish Power" so that the seal they put on the in-coming feed-side cover screw could not be removed by anyone without SP approval...

 

[CACJL]

Hi guys,

When installing a new CU does anyone ever install a 100A double pole isolator switch between the meter and the consumer unit?

Very often I come across 16mm tails which need to be upgraded to 25mm so I join the old tails to new in a Henley block and get the DNO to come and upgrade their side at their convenience.

Instead of using a henley block could I use an isolator instead?

In anyones opinion would there be any disadvantages to this?

I wouldhave thought having an isolator would be very handy but the meter guys hardly ever bother putting one in, even now.

They're also relatively inexpensive. Another thing, I cannot seem to finda 2-module metal enclosure so would this would be okay in a plastic enclosure? That to me seems like a bit of grey area.

Any help appreciated. Thanks

D MCBs would normally only used with Direct on Line electric motors.

 

[Michaelwgroves]

Similar switchgear assemblies
The phrase ‘similar switchgear assemblies’ in Regulation 421.1.201 means those assemblies used for the same fundamental application as a consumer unit. A consumer unit is defined in Part 2 of BS 7671:

‘Consumer unit (may also be known as a consumer control unit or electricity control unit). A particular type of distribution board comprising a type-tested co-ordinated assembly for the control and distribution of electrical energy, principally in domestic premises, incorporating manual means of double-pole isolation on the incoming circuit(s) and an assembly of one or more fuses, circuit-breakers, residual current operated devices or signalling and other devices proven during the type-test of the assembly as suitable for such use.’

Consumer units - IET Electrical - http://electrical.------.org/wiring-matters/55/consumer-units/index.cfm

I think Andy78's post is clear, the definition of a CU is;

SNIP.."an assembly of one or more fuses, circuit-breakers, residual current operated devices"

As the DP isolator has none of these it is NOT a CU or Similar switchgear assembly, therefore Regulation 421.1.201 does not apply.

You'll notice the Wylex Switched fuse's do comply, that's because they incorporate a fuse.

That's how I'm reading it?

 

[Deleted member 26818]

You'll notice the Wylex Switched fuse's do comply, that's because they incorporate a fuse.

That's how I'm reading it?

As long as you can find one that complies with BS EN 61439-3, you’ll be fine.

 

[Michaelwgroves]

SNIP

https://www.electrium.co.uk/media/20151123152755_0_Wylex Domestic Switch Fuse Unit.pdf​

This attachment confirms Wylex are compliant with BS EN 61439-3

 

[Deleted account]

I'm shocked. I'm always very careful measuring the run of the tails. Fingertip to opposite --- (1metre).

My meter is finger tip to cleavage.

 

[Spoon]

My meter is finger tip to cleavage.

You have a cleavage Pete??

 

[Deleted account]

You have a cleavage Pete??

I'm on a diet. Lost 10 pounds since Xmas. Hopefully I won't have a cleavage soon.
Then it will be finger tip to clavicle.

 

[Spoon]

This is me....

 

[brynmor steel]

Has any got a recommendation for a company in S. Wales that fits 100A DP Isolator Installation Between Meter and CU or is only the DNO that do?

 

[Michaelwgroves]

Has any got a recommendation for a company in S. Wales that fits 100A DP Isolator Installation Between Meter and CU or is only the DNO that do?

Any local spark can do this.

 

[Midwest]

Any local spark can do this.

Only if they are graced with seal fairies. ?

 

[pc1966]

Has any got a recommendation for a company in S. Wales that fits 100A DP Isolator Installation Between Meter and CU or is only the DNO that do?

It depends on the DNO's policy really.

Strictly speaking the sealed equipment is owned by the DNO or the billing company so only they should make changes there, but many DNO are OK with registered electricians doing it and some even provide temporary seals, etc.

What the DNO is really concerned with is folk trying to bypass meters to seal the supply, and the danger of pulling the main fuse to isolate if there is anything dodgy about the cut-out condition as shorting the incoming supply is going to end your day very badly. This is the sort of example to show the danger of working on a live supply:

They had proper PPE and probably were OK, their underpants probably less so.

So ask local electricians about it, they ought to know if the DNO is agreeable and/or if they already have permission to do that.