Black thing connected to electric meter?

[rayaans]

Hi,

Any idea what this black thing is connected to my electric meter?

Seems to be connected to the main electrical supply first and then into the meter

 

[Stevers]

In that position we have a black box with a stonking great plug in fuse that's solder tagged to prevent tampering. Pulling that fuse would disconnect the meter, consumer unit (and rest of the house wiring) from the electricity supply from the poles in the road. I suspect you have the YEB equivalent, with the fuse additionally protected from tampering by a cover. Very early in our renovations our fuse was removed by the sparky for some job he needed to do, and at our first meter reading the removed solder tag was replaced without protest by the meter reader.

It's reasonable to consider it the electrical equivalent of the stop cock in the road for a domestic water supply.

 

[a twig]

Oooh, not seen a mains fuse like that before! Looks very snazzy!

Looks like it could be one you’d normally see for 3 phase that they are only using 1 phase of.

 

[phillc]

It's difficult to get a scale of the thing and - of course - we don't know the rating of the cutout but those tails (the wires coming out of the top) look a little thin to me?

 

[Cubist]

I think @Zebra was a professional leccie, maybe she can confirm?

 

[Zebra]

Wha, sorry? Oh, yes, that's the service head, the joint between the incoming cable owned by the electricity distributor and the meter tails. Every property has one. Onto the bottom of it is your main earth (green and yellow wire), which means you have a TN-S incomer (earth and neutral separate) rather than a TNC-S (earth and neutral separate in the property but combined within the incomer), this wire is very important, do not remove it.
I assume your main fuse (mentioned by Stevers) is separate.
Basically you can't do anything with this thing, the service head. It's owned by the electricity distributor, as are the cables up to the meter. Even if the cables out of the top of it do look thin, it's not down to you or your electrician to change them. Incomers often are thin, way thinner than the legal requirements for the cables after the meter, which you do own, but that's just how it is.
I have occasionally moved a service head a bit - both in my house or someone else's - but only a short distance and without opening it up and (obviously) without shutting it off.

 

[Zebra]

And as for removing the security tag on the main fuse or meter, it's one of those things that everyone turned a blind eye to. The rules say you have to get the electricity company out to pull the main fuse and put it back in again, but nobody did that. I haven't worked as an electrician since 2016, so it may have changed, but every sparkie I ever knew pulled the main fuse themselves. I used to at least twist a bit of wire back on afterwards. Most didn't even do that. You can now buy the security tags on eBay, which even if they're not officially recognised, are better than nothing.

 

[paulc]

If/when you get the electricity meter changed to a smart meter, ask the supplier to fit an isolation switch. Tell them that you plan on installing an EV charging point in the near future, and they should fit an isolation switch for free (it goes between the meter and consumer unit). Makes life a lot easier should you need to do any work on the consumer unit and saves having to pull the main fuse.

 

[Flyfisher]

Basically you can't do anything with this thing, the service head. It's owned by the electricity distributor, as are the cables up to the meter. Even if the cables out of the top of it do look thin, it's not down to you or your electrician to change them. Incomers often are thin, way thinner than the legal requirements for the cables after the meter, which you do own, but that's just how it is.

We used to have an overhead supply to the house but I managed to get the DNO to replace it with an underground supply with the meter in an outbuilding (as prevously described on here somewhere). This required new underground SWA cabling from the outbuilding to the house CU. I was amazed at the size difference between the DNO cable to the meter and the cable our electrician used from the meter (via an isolator switch, as @paulc sensibly suggested above). From memory, the DNO cable was only about 1/2-inch diameter whereas the cable on the domestic side is about 1-1/2 inch. I know some of this is because the DNO cable is not SWA but even so I was surprised. When I mentioned it to our electrician, he told me the regs he has to work to are different to the DNO ones.

 

[a twig]

It makes sense - DNOs are in a working environment concerned primarily with efficient high voltage transmission and distribution which is only ever accessed by authorised and trained personnel - a whole different kettle of fish to residential electrics where you have to mitigate against enthusiastic and knowledge bereft members of the public could do any number of mad things.

 

[rayaans]

Thank you for the replies. We've had the whole house rewired along with outbuildings so was a bit confused why this thing was still there

Will leave it well alone of course!