Difficult Service head

[Lorzor]

Hello all,

I've recently put a new circuit in a house and when filling out my EIC, I needed to access the service head (attached).

I'm relatively new to this and I'm struggling here.

In order to access ANY part of this, you have to pull the main fuse and I had to cut a few metal tallys off. As you can see on the left is where the main fuse sits, to the right there is a cover for the MET and underneath is a cover for the incoming cables. The black box between the meter and thefuse housing is not removable - I can't see where the main earth is. The earth cable you can see is bonding from the gas pipe.

Also, immediately I thought it was a TNS system but it gets quite strange. The what looks like SWA is not SWA, it looks and feels like copper!! IT DEFINITELY isn't steel. Additionally, I can't find a neutral anywhere, I can't see if it is in with the red incoming wire but I'd be pretty surprised if it was.

Could the copper SWA (I know) actually be the PME neutral and we are actually looking at a TNCS system here?

Either way, I have never seen anything like this cable before.

Thanks in advance, I genuinely don't know if I'm just being stupid or inexperienced here but I'm kinda stuck with a way ahead.

View attachment 35655

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[Lorzor]

Ok to confuse things more the Ze test is 0.11 ohms - it is not TT.

That earth you can see is 100% definitely the gas pipe bond.

 

[Pete999]

Hello all,

I've recently put a new circuit in a house and when filling out my EIC, I needed to access the service head (attached).

I'm relatively new to this and I'm struggling here.

In order to access ANY part of this, you have to pull the main fuse and I had to cut a few metal tallys off. As you can see on the left is where the main fuse sits, to the right there is a cover for the MET and underneath is a cover for the incoming cables. The black box between the meter and thefuse housing is not removable - I can't see where the main earth is. The earth cable you can see is bonding from the gas pipe.

Also, immediately I thought it was a TNS system but it gets quite strange. The what looks like SWA is not SWA, it looks and feels like copper!! IT DEFINITELY isn't steel. Additionally, I can't find a neutral anywhere, I can't see if it is in with the red incoming wire but I'd be pretty surprised if it was.

Could the copper SWA (I know) actually be the PME neutral and we are actually looking at a TNCS system here?

Either way, I have never seen anything like this cable before.

Thanks in advance, I genuinely don't know if I'm just being stupid or inexperienced here but I'm kinda stuck with a way ahead.

View attachment 35655

View attachment 35656

View attachment 35657

Put it all back together, clean your finger print and any DNA from the area, claim you had amnesia if anyone says anything, you shouldn't be frolicking about inside the head it's not yours to play with.

 

[Midwest]

Ok to confuse things more the Ze test is 0.11 ohms - it is not TT.

That earth you can see is 100% definitely the gas pipe bond.

Was that 'gas' bond been disconnected when you did your Ze test?

 

[Pete999]

Are you sure that is the gas bond, what Ze have you got.

Don't think that's the gas bond Westy thats the main earth to the CU and OP for info that cable is a concentric cable

 

[Lorzor]

Put it all back together, clean your finger print and any DNA from the area, claim you had amnesia if anyone says anything, you shouldn't be frolicking about inside the head it's not yours to play with.

Thanks for the advice but believe me, I have been told enough.

 

[Des 56]

Ok to confuse things more the Ze test is If that is a Gas bond, how did you measure Ze without verifying the earthing conductor 0.11 ohms - it is not TT.

That earth you can see is 100% definitely the gas pipe bond.

If that is a Gas bond, how did you measure Ze without verifying the earthing conductor

 

[Pete999]

If that is a Gas bond, how did you measure Ze without verifying the earthing conductor

Think that's the main earth to the cu, any bonding conductors will/should be on the earth bar in the cu imo

 

[Midwest]

OP, as already advised by members, think you just need to go back to basics, and verify earthing conductor and main bonding conductors, just in case you've made a mistake. We are all human.

 

[Lorzor]

Was that 'gas' bond been disconnected when you did your Ze test?

Yes

 

[Lorzor]

OP, as already advised by members, think you just need to go back to basics, and verify earthing conductor and main bonding conductors, just in case you've made a mistake. We are all human.

Yep, I'm going to start again, this is turning into a mess.
Thanks for all the advice everyone.

 

[Andy78]

I understand that I may have been hasty to take apart the service head but I have a job to do and I don't want to be wasting time. I'm not going to lose any sleep about cutting some tallies off. I'll phone up the suppliers, If they're going to get upset about it then I'll take it up with them.

Now to sound like a complete -------: while I'm new to the domestic game (and service heads!), I am an electrical engineer trained to degree level through an apprenticeship with 15 years experience in industrial electrics.

Then you should already be aware of concentric cable, test methods for establishing earthing arrangements, investigation methods for establishing methods of earthing, and remedial action to be carried out to rectify earthing problems.

I'm not belittling your qualification or experience, but degree or no degree, there still exists the probability of not having sufficient training for the task you are doing.

 

[Des 56]

Think that's the main earth to the cu, any bonding conductors will/should be on the earth bar in the cu imo

I expect you joined the thread late Pete,I refer you to the post I made previously

quote
That 10mm or 16mm green /yellow is probably your earthing conductor from the cut out to your consumer unit
You can verify with a continuity test
At the consumer unit you may then find some bonding cables for services

 

[Midwest]

Yep, I'm going to start again, this is turning into a mess.
Thanks for all the advice everyone.

Take a deep breath, and go through each step in a logical fashion.

Ps when you've done, I would certainly ask the DNO to have a look at their cable termination, they might fit a proper shroud or they might say it's fine. Least you can note you've done so on your EIC.

 

[Lorzor]

Then you should already be aware of concentric cable, test methods for establishing earthing arrangements, investigation methods for establishing methods of earthing, and remedial action to be carried out to rectify earthing problems.

I'm not belittling your qualification or experience, but degree or no degree, there still exists the probability of not having sufficient training for the task you are doing.

Absolutely, and I won't do it again. My point is that I understood what I was doing was dangerous - potentially fatal if done incorrectly. I wanted to visually check which earthing arrangement it was before carrying out a test and I was a bit hasty in dismantling the head whereas I should've done the tests. Lesson Learnt.

 

[Wilko]

Don't think that's the gas bond Westy thats the main earth to the CU and OP for info that cable is a concentric cable

If it really is only connected to the gas then installer has got their wires crossed