Why CU AND fuse box

[RegB]

Hi guys, I'm just trying to get to understand the electrics of an old cottage I've just moved into. Does anyone know why I'd have an old style fuse box (with six 15 amp fuses)AND a new consumer unit. Shouldn't there just be a CU? Pic here:
http://freespace.virgin.net/c.kennard/fuses.jpg
I've noticed that a partial rewire seems to have been done in the house since the socket circuits look new while the lighting circuits are old. Could it be something to do with this? Thanks for any advice.

 

[breezer]

(with six 15 amp fuses)

didn't have storage heaters did it?

 

[RegB]

Hi Breezer, No, there are no storage heaters - at least not now. Maybe there were before I moved in. There are no other high load devices either apart from a cooker and immersion but they run to the CU. Maybe, as you suggest, this is the fuse box for storage heaters since removed but I wonder why the fuse box would be kept in that case.

 

[breezer]

I wonder why the fuse box would be kept in that case.

just a guess.

heater can be dissconneted, and removed by average diy person, cu can't.

where is the mains supply from? is it from Exactly the same place as the new CU (but then again the meter you have looks like its been changed)

 

[RegB]

Yes, the mains supply comes from the same place. It isn't so clear in the picture. Anyway, there's no problem so perhaps I'll just ignore it. I just like to know what's going. Thanks for your ideas.

 

[mapj1]

If you pull the fuses out one at a time, and see what no longer works, (a test lamp is good for checking sockets) you'll know for future reference, and it will save time if you have problems later if you have this all noted down in advance. Preferably on a label on or near the board itself.
This info is so much harder to deduce when its dark and cold, you've come back off holiday and the freezer has thawed! I'd suggest finding out at rthe next free warm weekend!
just a thought.
M.

 

[Lectrician]

Can you take a head on photo - so we can see the meter position.

Looking at the arrangement, Eddy Currents, Grommet, & Earthing spring to mind

One tail through a hole in the metal CU, the other under the CU

Oh, and do you think a finger would fit in the knockout on the side of the CU

 

[RegB]

OK I think I've sorted it out now, thanks to all your help.There's a head-on shot here Lectrician:
http://freespace.virgin.net/c.kennard/mixed2.jpg
(sorry it's a composite but the space is narrow). Took your advice Mapj and found that the wires from the fuses lead to single sockets in each of the 4 downstairs rooms. These rooms all have double sockets as well, running to the CU so it seems these single sockets were put in for a special purpose. Maybe storage heaters after all, though aren't they supposed to be wired directly into the circuit, not using a plug? Not sure if these sockets are legal now since they're only on a 15 amp circuit but that's another problem. Anyway, thanks for all your help for such a small question.

 

[HDRW]

OK I think I've sorted it out now, thanks to all your help.There's a head-on shot here Lectrician:
http://freespace.virgin.net/c.kennard/mixed2.jpg
(sorry it's a composite but the space is narrow). Took your advice Mapj and found that the wires from the fuses lead to single sockets in each of the 4 downstairs rooms. These rooms all have double sockets as well, running to the CU so it seems these single sockets were put in for a special purpose. Maybe storage heaters after all, though aren't they supposed to be wired directly into the circuit, not using a plug? Not sure if these sockets are legal now since they're only on a 15 amp circuit but that's another problem. Anyway, thanks for all your help for such a small question.

Interesting photo(s) - nicely spliced!

A couple of things puzzle me:

What's the cable (neutral?) that goes from the Henley block to the left-hand CU? It bypasses the meter, which doesn't sound right. I suppose it's possible there was a night-rate meter once, feeding the CU in question, and removing that has left this setup.

Where's the Earth?

Cheers,

Howard

 

[Lectrician]

Yea, that head-on photo shows what I suspected.

There is no earth from the REC, and if it is a TT earthing system, there is no RCD.

The neutral feeding the old fusebox should be routed through the same hole as the live, to avoid overheating the cable due to eddy currents.

It is very common to find single sockets fitted inplace of the old storage heater isolators. A 15amp fuse protecting these is fine.

The neutral is on the incorrect side of the meter, but this will not affect the metering, but isnt correct.

You really do need some work done to put this installation in a safe condition. I seriously think you need an electrician to take a look, especially re the earthing.

Oh, and the composite photo is great

 

[mapj1]

I hope there is an earth rod or similar just outside the house, as clearly no earth comes in with the supply!
If you have an earth rod as your only external earth, then unless it has a very low resistance indeed, it will not blow the fuses (or circuit breakers) if ever there is a fault, instead simply allowing the metalwork in the house and the ground aroud the rod to be partly 'live' and to give you a large electricity bill instead.
As a minimum an RCD (which will trip the lot if there is even a small earth fault) should be added after the meter and before the CU. In your case I think this is definitely not a DIY job.
Better would be two, a slow one for fixed installation and lights, and a 30ma normal one for sockets. This ywould mean a faulty applience wont kill the lights
Note that the meter has been changed, but the supply company have not refused to reconnect an installation that is potentially hazardous.
Get it looked at soon, please.
Regards M.

 

[RegB]

Thanks for your observations Map, Lectrician and HDRW. In fact, I think there is an earth cable but it didn't show up well in the photo. It's right at the top of the cu. A thick cable comes through the ceiling and connects to the bolt at the top of the cu (pic here : )
http://freespace.virgin.net/c.kennard/earth.jpg
I thought that apparent bypass was odd too. Can't be getting free power to the sockets surely! Of course, as you urge, I will definitely get a pro in to look at this - I know my limitations - but it's still very useful to get a basic understanding of the situation from experts such as you. Thanks again.

 

[plugwash]

my guess is the dual rate metering kit was removed and the off peak fusebox disconnected then someone (possiblly as soon as it was removed possiblly later) connected it to the normal supply and replaced the storage heater outlets with sockets

the live he picked up by sticking a second wire in the CU live terminal (which isn't generally considered good practice but as long as the cables are gripped tight probablly isn't a major problem. The neutral cable he has wired direct to the neutral block by the service fuse.

the incoming cables seem to be two seperate single cores of some sort So its not beyond possibility that its TN-S with a totally seperate earth wire.

there is also no rcd protection on that install whatsoever (on either of the CUs)

the earth bar in the newer CU in that picture also seems to be missing.

this needs to be checked out by an electrician asap

 

[ban-all-sheds]

Thanks for your observations Map, Lectrician and HDRW. In fact, I think there is an earth cable but it didn't show up well in the photo. It's right at the top of the cu. A thick cable comes through the ceiling and connects to the bolt at the top of the cu (pic here : )

1) That cable is not marked as being an earth
2) Do you know where it goes?
3) That bolt is not an approved earth clamp/connection
4) It looks loose anyway
5) The whole thing is a lash-up.

I thought that apparent bypass was odd too. Can't be getting free power to the sockets surely!

Sadly, you aren't

 

[Adam_151]

I don't think he meant that cable, ban all sheds, I think he means the yellow and green one that is under your arrowhead, the cable you pointed to, to me, it looks more like its cut off rather than going into the bolt, maybe an old vir cable or something?, you could be right and me wrong though

One other thing that I can't remember anyone saying, is if you look at the neutral block, you can see that the twin and earth is the old stranded stuff