Met

[kingeri]

Imagine the scenario, you have two CU's in an installation and no external MET. The main earthing conductor goes to the earthing terminal in one of the CU's and the main bonding conductor goes into the earthing terminal of the other. The earthing terminals of the two CU's are joined together with 16mm. Which is the MET / is this permitted? I wouldn't do this, but I've come across it a lot. The MET can be external to the CU or it can be the earth bar inside the CU, but can it be 'split' across two CU's (if you see what I mean?).

 

[keniff]

You can join 2 earth bars together so I don't see why not? I think there's a reg where if you join them, they can only be seperated by use of a tool. I may be making that up though

 

[KAS1]

I've always installed a MET separate from a CU, never liked the idea of main bonding conductors being connected in the CU

 

[Engineer54]

Imagine the scenario, you have two CU's in an installation and no external MET. The main earthing conductor goes to the earthing terminal in one of the CU's and the main bonding conductor goes into the earthing terminal of the other. The earthing terminals of the two CU's are joined together with 16mm. Which is the MET / is this permitted? I wouldn't do this, but I've come across it a lot. The MET can be external to the CU or it can be the earth bar inside the CU, but can it be 'split' across two CU's (if you see what I mean?).

Yes it's permitted, though as you say not the best of set-ups. The main earth conductor dictates which of the CU earth bars is the MET, the other CU,s earth bar then becomes the EMT!! Which the connecting 16mm conductor links both together!!

 

[Elmer BeFuddled]

I've always installed a MET separate from a CU, never liked the idea of main bonding conductors being connected in the CU

Out of curiosity Kas1, is that contained in a junction box next to the CU/meter cupboard, or 'exposed'?

 

[Engineer54]

Out of curiosity Kas1, is that contained in a junction box next to the CU/meter cupboard, or 'exposed'?

Why would you enclose an MET block??

 

[Elmer BeFuddled]

Why would you enclose an MET block??

Keep peeps fingers off it? Only a curious question which I'm allowed after all. I've seen both, covered and exposed.

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Wish I hadn't asked now!!

 

[Guitarist]

You can join 2 earth bars together so I don't see why not? I think there's a reg where if you join them, they can only be seperated by use of a tool. I may be making that up though

GN8 shows a double MET with a disconnectable link to allow testing. I think this may be where you've seen it.

 

[kingeri]

I also always install an external MET. Was just curious cos I see all kinds of setups out there. The one I'm looking at now has an external earth block which the main bond goes into. This then connects to two CUs (so it has 3 conductors connected to it). But the main earth conductor goes into one of the CU's! The only reason I can see that it was done this way is that the bonding and main earth wires won't reach to the same point, and the last person couldn't be bothered to replace one of them.

 

[Guitarist]

I think CBA contributes to many installs

 

[Engineer54]

Keep peeps fingers off it? Only a curious question which I'm allowed after all. I've seen both, covered and exposed.

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Wish I hadn't asked now!!

Same as my question then!! lol!!

I think we've all seen both, but i can't think of a single reason why you would want to enclose a MET? Some of our METs are 2m long removable link earth bar's, with 240/120mm etc, earth and bonding conductors connected to them...

 

[kingeri]

What's the point of enclosing a MET when all the bonded metal is open to be touched?

 

[Robotstar5]

What's the point of enclosing a MET when all the bonded metal is open to be touched?

To stop the enthuiastic diyer fiddling with it? you know, the type with only one screwdriver normally used for stirring paint, keeps it in his toolbox along with the broken hacksaw blade and a rusty claw hammer

 

[Engineer54]

To stop the enthuiastic diyer fiddling with it? you know, the type with only one screwdriver normally used for stirring paint, keeps it in his toolbox along with the broken hacksaw blade and a rusty claw hammer

Do you honestly think that would stop an ''enthuiastic'' diyer?? Pointless exercise!!

 

[lister101]

Do you honestly think that would stop an ''enthuiastic'' diyer?? Pointless exercise!!

Tamper head screws might be the way forward but that might only increase their curiosity!