Earth wire space

AS · 17 Jan 2005

Am planning wiring an extra light into a circuit served by one big JB containing a strip of connectors which all lights and switches come from. There are 5 lights on the circuit and I am planning connecting in a 6 th : total 600W.

Problem is I cannot get another earth wire into the connector block as not enough space can I put the extra earth wires into a spare bit of connector stip in the box or do they all need to make contact with the earth coming from the feed and therefore have to all go into that bit of connector. If so how do I solve this .would I need to get bigger connector for the earths?

securespark · 17 Jan 2005

Ditch the strips and use proper JB's.

AS · 17 Jan 2005

Are these large JB's not good -
I wasn't planning to rewire the whole house just add a few lights into the existing circuit which has 3 of these boxes each going to a seperate fuseholder in the CU.
i thought they seemed quite good as all in one place.
If I change to individual JB's would this be better and would it mean undoing all the existing circuit which runs from this box and re running it all with seperate boxes?
Is it safer to have 6 x4 terminal JB's next to each other in the loft than 6 lights/cables going into one bigger JB?

plugwash · 17 Jan 2005

nothing wrong with using a big box with terminal block in to do your connections and has the distinct advantage of keeping stuff easy to change.

also nothing wrong with connecting multiple terminas together when you need to connect more than a few cables.

its probablly never a good idea to put more than two or three cables in a terminal or some of them might well come loose depending on who the terminal happens to tighten.

AS · 17 Jan 2005

Thanks,
I think I will run the feed to a new box and put the new light into that so there are less cores in each terminal and plenty room for the earths.

Not that this is relevant if i do it this way but out of interest from my original question do all light cable and switch cable earths need to connect to the feed cable earth or can they connect to a spare terminal?

mapj1 · 17 Jan 2005

The most important thing is that all the lights and all the switches do eventually connect back to the main earth terminal. How many joints are on the way is only important in so far as the connectors should not be overfilled, and should be secure. To that end almost any combination of junction boxes and terminals would be allowed, providing they are of adequate size.. Make sure that you can get to them later if you ever need to though, either for expansion or inspection of the installation.

regards M.

ban-all-sheds · 17 Jan 2005

AS said:
Not that this is relevant if i do it this way but out of interest from my original question do all light cable and switch cable earths need to connect to the feed cable earth ?

Of course they do, and the fact that you even suspected that they might not gives me the willies. Do you know anything about electrics?

securespark · 17 Jan 2005

I suspect the answer he was looking for was "No, it does not matter what you do with the earth wires, they're not important....."

But the fact is they are important, and earth continuity needs to be maintained throughout.

As I learnt at college, "The cpc is the most important of the 3 conductors in a SP circuit......."

AS · 18 Jan 2005

The reason I was asking about the earths is because in one of the existing JB's all the earths were not connecting in with the feed cable earth and I thought this odd - I guess they did this due to lack of space. If I add on extra boxes then there should be ample space and I can rectify this fault in the original wiring of the JB.

Thanks for help

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Earth wire space

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