Earth to garage?

[p4ult]

Hi guys,
This is my first post on this forum, has been a great help so far. But now I have a question that I cant find an answer to by searching.

Ok, I have recently moved house, the house has a detached garage, the house was built in the 50's but i don't know when the garage was built. The garage has 2 lights and a number of sockets fed from a separate fuse box in the garage which is fed from the main fuse box in the house. The wiring in the house has been updated recently but the wiring in the garage looks quite dated. All the sockets and cables are in metal conduit. Being a keen DIYer I switched off the power and took off one of the sockets in the garage to inspect the quality of the wiring.
I was suprised to see that there was no earth wire in any of the sockets!!!!!
Now my questions are:

1, are the sockets earthed via the metal conduit?
2, will the fuse box be earthed if its connected the the house supply?
3, can i check this?
4, is any of this safe or do I need to get it all replaced?

Thanks, and sorry for the lengthly post and questions
Paul

 

[luminaire]

Is the fusebox in the garage metal or plastic?

 

[JohnD]

(1) and (2) are "Maybe"

Can you post some pics of the CU, sockets and cabling?

If you are able to isolate the supply to the garage and post some pics of the CU with its front panel taken off, that will help.

//www.diynot.com/forums/viewtopic.php?t=99672

 

[p4ult]

Is the fusebox in the garage metal or plastic?

Its metal

 

[p4ult]

(1) and (2) are "Maybe"

Can you post some pics of the CU, sockets and cabling?

If you are able to isolate the supply to the garage and post some pics of the CU with its front panel taken off, that will help.

//www.diynot.com/forums/viewtopic.php?t=99672[/QUOTE]
Yeah can do, will get some tomorrow as its dark now

 

[p4ult]

Thanks for your reply guys

 

[p4ult]

Ok guys, just gone and had another look and took some pics, I cant see an earth on the pic of the open socket.

Was this standard practice not to earth years ago?

Sorry about the no of pics

 

[JohnD]

an old job, but high quality when it was installed.

you have no apparant earth wire because the "conduit" is actually a copper sheathing to the cable.

The copper sheath acts as the earth conductor.

Do not try to cut or alter the cable as it neeeds professional tools and the ends have to be sealed tp prevent moisture getting in and attacking the compressed powder insulation. the cable ends will be fastened into the back-boxes and the CU with brass glands.

It would be a good idea to fit a wire link between the earth screw in the metal back-box, and the earth terminal of the socket faceplate. Otherwise you are reliant on the integrity of the fixing screw to the backbox tags (these can go rusty or loose). the link should be green-and-yellow of 2.5mm or greater. you will find it in DIY shops.

the CU is a very old one with rewirable fuses, there are frowned on today as people sometimes fit the wrong size of fusewire.

You could change the socket front plates for new metalclad ones if any of them are damaged, without disturbing the backbox behind. You can get sockets with an integral RCD but they are not cheap.

Sockets in a garage ought to be protected by an RCD. I do not think you could fit one yourself with pyro cables, but it might be easier to do where the supply originates in the house, if that can be done without disturbing the copper-sheathed cables.

If you have to pay a professional, you might as well fit a modern CU with RCD protection, and have him fit modern double switched socket outlets. It might even be cheaper to rewire completely in PVC.

That copper-sheathed cabe is seldom fitted in domestic installations but electricians who also do industrial work will be used to it. It will last almost indefintely if not disturbed. It is resistant to fire.

 

[dannyboi2003]

Wow a proper belt and braces installation there and in a garage too!

I agree with JohnD's advice about the earth link, with regards to having it replaced then i would say that if you have enough sockets for your needs and the lights are ok then id leave it alone.

The only thing i would do is have a spark give it a once over to make sure its all in good order and that the fuses have the correct fuse wire in them. Also as the sockets will be used to feed equipment outside then you need to make sure they are RCD protected, the only was of doing this without any major alterations is to feed the garage from the RCD side of the consumer unit in the house, this would also include the garage lights but i cant see this being a huge problem. It may already be RCD protected in the house, can you post a pic of the CU in the house and point out which MCB supplies the garage and what rating it is? Also can you show us the cable run between the house and garage or is it all buried/hidden?

All the best
Dan

 

[p4ult]

Thanks for your replies so far guys, very much appriciated.

The cable that feeds the garage is laid under concrete as the garage is detached.

Just had a look at the CU in the house, the MCB is blue coloured and has 16A on it, this means 16 amp I guess. Its not a RCD. So I take it that it would be a good idea to replace it with an RCD?
I will also earth the sockets like has been suggested.

Thanks
Paul

 

[JohnD]

IF you can get a single-width RCBO to fit it that would be ideal.

But "blue coloured" makers me think of Wylex Standard, and RCBOs are not available.

Can you post a pic of the house CU?

 

[p4ult]

Yes it is WYLEX

CU with garage switch removed

Removed switch

 

[p4ult]

I have also just found this, it is connected to the cable that comes from the garage and is wired before the CU, is it of any use?

Thanks
Paul

 

[JohnD]

You cannot* fit an RCD or a RCBO to that range.

It would be possible to fit an RCD in the cable between the CU and that switchfuse; or to replace the switchfuse with an RCD in a metal enclosure. this would need to be done by a professional as it involves remaking the Pyro joint. If phoning a recommended local electrician, tell him it is to work on Pyro, and ask if he is a member of a self-certification scheme, and which one.

(Pyro is a ?trade? name for that fire-resisting copper-sheathed cable. It is essential that the end is sealed.)

As the Switchfuse is fed from an MCB-protected circuit, the fuse is unnecessary.

*there is an accessory kit to protect a single circuit, but it is expensive and fitted externally, so I can't see the point)

p.s. If you feel the need to remove those plug-in MCBs, you MUST switch them off first. it is not usually necessary to remove them.

p.p.s It would be useful to put labels above the MCBs to say which circuits they protect. You can do this using white vinyl tape and a permanent marker. You can make them neater if you write them before sticking the tape to the CU.

 

[p4ult]

So it would be cheaper to get an RCD fitted in between the switch and the CU?
What type would I need and is it a big job?

Again thanks for your help John