Not one, but three 100A Fuses at the 'Service Head'prior to the Meter in a home about 30yrs Old?

It is unusual but not unheard of.

Is it a big house? Rural or urban?

If the house required a three phase supply on 100A fuses it must have been drawing some load.

Houses with this sort of load generally have a lot of electric heating or an owner who enjoys wood turning or similar.

Thanks Ianh,
Urban, 3 bed. As far as I could see, (under the stairs full of junk). One fuse is used for the supply -> Meter -> Fuse Box. The other two are looped in off the first one, but dont have any outfeed.
What's the usual supply to the Service Head rated at then if you could possibly use 3 X 100A Supplies?

I'm not sure if I understand your description. Are you looking at a three phase service head, or a single phase service with looped services?

The service cut outs will run at 100A continuously but it will depend on the size of the incoming cable.

Can you get a photo of the setup?

If I remember rightly, I think it was a Single phase supply, but it was boxed in.
The first 100A fuse was used for the supply,to the house hold, I think the other two 100A fuses were looped across the infeed, but there was no visible outfeed.
I was curious why three fuses?

I'll try to get a photo but not sure how to post it on here,or post a sketch!

Cheers!

Ianh,
Here's a couple of photo's without the cable covers, & with Harry Potter shoved out the way!!.




{Message edited to insert images}

[This message has been edited by Trumpy (edited 03-06-2006).]

Hm, so basically the fuses are all connected to the same phase and two of them are simply unused. Preparations for multiple metering?

Btw, black neutral and grey phase, what's that???

Texas_Ranger hit the nail on the head there - this is the sort of installation that would have been put in where a property would require seperate meters for flats etc. It is strange to see two fuses looped off the main cut-out (service head) as it does seriously reduce the load you can supply.

With a single looped service, you could put two 60A fuses in and rely on the diversity etc to prevent an overload. With two loops, you would only be looking at 30A fuses - more than enough for a one bedroom flat though.

It is unlikely that a PoCo would allow two loops these days - one is still acceptable over here, but a second would require a three phase service head, and a phase each.

The 100A written on the side of the fuse carriers is the maximum rating of the assembly, not the fuse size. A cut-out like this would normally have a maximum fuse size of 80A, as they will allow the current to exceed 80A for a while. If you wanted a 100A service, you would need a three phase heavy-duty cut-out

With regard to the conductor colours, these should either be red (phase) and black (neutral) or brown (phase) and blue (neutral) - these tails don't meet either of the current requirements!

One other thing - removing the cable cover on a service head in the UK can be seen as a revenue protection issue!

This is on a par with removing the meter seals and should not be done unless you have something in writing from the PoCo / metering company. The penalties can be quite severe!

I'm assuming the covers were over the unpainted areas and these covers would have been installed to prevent access to the tails prior to the meter. They should have tamper-proof stickers over them to prevent the screws being removed.

Once you have finished any work, you might consider letting the PoCo know that it wasn't sealed in case they want to come and re-seal it.

Cheers

Ian

The gray will just be the outer sheath though. It quite likely has red inner insulation:



I still see three different types of meter tails in service around here. The modern ones are red/black inner insulation with a gray outer (brown/blue inners for that new-fangled Euro-stuff, of course).

Older tails can have either a brown sheath, or a red/black sheath to match the inner insulation, i.e. they still have a double layer of insulation, but both are red or both are black. So my guess on that pic is that the phase conductor into the meter is a replacement and that the neutral is older. Either that, or somebody just used single-insulated (6491X) for the neutral.

That's an interesting point. It looks as though this installaton is fed with concentric cable by the look of the taped up neutral, so it quite probably did have a cover of some sort. However there are many services in which the incoming lines are quite easily accessible -- For a start, practically all the overhead services here in which the two cables just drop down through the wall or roof void and terminate into the fuse and neutral block.


[This message has been edited by pauluk (edited 03-06-2006).]

**quote
The gray will just be the outer sheath though. It quite likely has red inner insulation
** end quote

D'oh - of course it will. All these colour changes are confusing!


**quote
practically all the overhead services here in which the two cables just drop down through the wall or roof void and terminate into the fuse and neutral block
** end quote

True enough for days gone by, but it is unlikely that any PoCo will install a service like that these days.

Any exposed service cable will be concentric to stop people tapping off the phase conductor, and anywhere where the phase conductor is exposed should have a security cover over the top.

Edited 'cos I can't work out how to put the quote things in using UBB!

[This message has been edited by ianh (edited 03-06-2006).]

Ianh,
I took the covers off so you could see the set up, as you wanted a photo. Dont worry they were only on with a couple of wood screws & no seals.
As you can see from the photo the seals on the fuses are intact as is on the Meter.
The Grey supply Phase is an outer protective sheath on red insulation.

Paul got it spot on...(again)!
Don' forget this is about 30yrs. Old.

I originally went in this cupboard to get under the floor to help my workmate shift a radiator, now I'm sneaking photos of his dirty laundry!!!! LOL

Click on the edit icon on this message to see how I quoted your text (the system won't let you actually change anything, but you'll get the edit box up and see the codes).

There's a summary of the UBB codes here:
https://www.electrical-contractor.net/ubb/ubbcode.html


[This message has been edited by pauluk (edited 03-07-2006).]