Main Supply Isolator Switch (REC Switch)

Hi there. I've got a simple question about isolator switches like this Wylex 100A one. Their datasheet says:

but their diagram shows it between the Meter and CU. I'd prefer it to be placed before the Meter as then everything can be isolated. Is that OK or are they going to worry about tampering?

I'm aware how hairy all of this is so the profesionals will be used, but I like to understand the layout and it sits on the interface between sets of professionals, so if I can have it before the Meter, I'll buy it before UKPN come and connect the main feed and ask them to terminate to the isolator switch.

Thank you for your help.

From Wylex datasheet:

SelfBuilder101 said:

or are they going to worry about tampering?

Click to expand...

In a word Yes.....

Thank you bernardgreen. I see that the switch itself has security features on the screw holes that presumably allow the sealed twisted wire tamper detectors. I've copied a couple of pictures below. These would stop tampering of the isolator (REC) switch, but not stop someone putting something else in-line before the meter I guess.

Is the ensured Live Therefore Dangerous method really the right anti-tamper approach. If you are inclined to tamper then you'd probably be brave enough to do something else stupid with live wires.

I would hope safety out ranks security. Not the safety of some unlikely tamperer, but the safety of all the likely people that will benefit from an isolated meter and everything else.

Photo of whole Wylex 100A REC switch:

Close-up photo of anti tamper feature on screw holes:

Even with the seals, if you can isolate the supply to the meter, it makes it easier to illegally abstract a supply.

Anyone who is authorised to work on the meter will have procedures in place to isolate the supply by removal of the cut-out fuse.

SelfBuilder101 said:

the safety of all the likely people that will benefit from an isolated meter and everything else.

Click to expand...

Who are the likely people to benefit from the meter being isolated?

Up to and including meter is not yours it belongs to DNO you can't touch it, you can only fit things after the meter, in theory the HSE tells us before working on a panel it must be isolated elsewhere, so in theory before working on a consumer unit one has to either switch off an isolator like you show, or pull the DNO fuse, however we should not touch the DNO fuse, so in theory the DNO should provide us with a means of isolation. However in practice it is rare for this to happen. Two wrongs don't make a right, however without the isolator the DNO can hardly complain if the fuse seal is broken, specially if you tell them it's been broken rather than wait for them to find out.

Again theory you should ring them up allow them to disconnect, do your work, then ring them up and ask for a reconnection, yes and that is really going to happen! There is normally a little leeway given to electricians who break seals for good reason for example replacing a consumer unit.

Today I am really not sure what is permitted. Since the fire retardant consumer unit rules came in, not sure if you can have an isolator in a plastic box? Screws can be left loose in an isolator on its own just as easy as when built into a consumer unit. Doing an internet hunt for "amendment 3 isolator" brings up a host of isolators in a metal enclosure so I think either the isolator needs to be in a metal box, or the whole system is enclosed in a metal box, I have not got a copy of amendment 3 so not sure what is required. Since the supply trade does not come under BS7671 the DNO can use a plastic box, but not sure about anyone else?

SelfBuilder101 said:

wire tamper detectors.

Click to expand...

have no value in safety or tamper prevention.

Frequently the connection between cut out and meter is made tamper proof by replacing tails with secure connections

SelfBuilder101 said:

"It’s safer because the supply tails are fixed and finalised in a sealed unit – instead of being left hanging loose ready to connect to the meter."

​

Click to expand...

Maybe they mean the other way round, the supply cables in the CU end.
where you have fitted your Consumer unit, but yet to have your supply or the meter installed, how often that happens I dont know.
Technically your not meant to touch the meter, so I assume you can connect your Consumer tails in it ready, for the authorised person to link it to the meter, as opposed to hanging out the Cu which may stress the connection in the Cu main switch.

Thanks for all the replies.

ban-all-sheds: It would be safer for the meter installer. I'm expecting we will be upgrading our meter to a smart meter in the near term and an isolator switch would make that easier. Regardless of that, intrinsically it has to be safer to have the option of straightforwardly isolating the supply. Do meters (which I note are mostly plastic) ever catch fire?

I just don't buy the rationale of keeping it live makes it tamper proof as I have seen loads of poles in other countries with loads of illegal taps and that would have been done when Live. Anyone minded to steal electricity wouldn't be put off by it being permanently Live.

Thanks bernardgreen. How common is electricity theft? Surely any tap offs would be really obvious on unscheduled inspection.

Thanks 333rocky333. A CU without being connected to the feed (via the meter) wouldn't be any risk surely. Therefore neither would its tails. They must be referring to the ones coming from the main feed.

SelfBuilder101 said:

It would be safer for the meter installer.

Click to expand...

Not your responsibility nor concern.

I'm expecting we will be upgrading our meter to a smart meter in the near term

Click to expand...

Do you want one? Again, for whose benefit do you think it would be?

and an isolator switch would make that easier. Regardless of that, intrinsically it has to be safer to have the option of straightforwardly isolating the supply.

Click to expand...

Not your responsibility nor concern.

Do meters (which I note are mostly plastic) ever catch fire?

Click to expand...

I suppose we can't say never but it is not a consideration.

I just don't buy the rationale of keeping it live makes it tamper proof

Click to expand...

You are free to disagree.

as I have seen loads of poles in other countries with loads of illegal taps and that would have been done when Live.

Click to expand...

Did any of them get hurt?

Anyone minded to steal electricity wouldn't be put off by it being permanently Live.

Click to expand...

That may be so but you and others may and should be.

You are arguing needlessly. That is how it is done and will be done.
It is not your concern.

SelfBuilder101 said:

I'm expecting we will be upgrading our meter to a smart meter in the near term and an isolator switch would make that easier.

Click to expand...

Meters are not replaced live, and there is already means of isolation in the cutout.

SelfBuilder101 said:

ntrinsically it has to be safer to have the option of straightforwardly isolating the supply

Click to expand...

That's what the switch in your consumer unit is for.

If you insist on having this isolator installed, it will be after the meter.

Sorry EFLImpudence. I'm not trying to argue, just trying to understand.

Fair enough.

The DNOs and Suppliers (used to be the same, of course) are very protective about what they term their property and try to make it as difficult as possible for us mere customers and electricians.