• IMPORTANT: Please note that nobody on this forum should be seeking from or providing advice to those who are not competent and / or trained and qualified in their field (local laws permitting). There is a discussion thread on this global industry-wide matter HERE. This also has more information about the warning with regards to sharing electrical advice in some countries. By using this forum you do so in agreement to this.

Discuss How do we solve the long meter tail problem? in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
45
Just seen a you tube video by Artisan, he mentions there is a 15 meter run that goes in the fabric of the building from the meter/100amp cut out to the consumer unit.
it started a debate as to whether to code it a c2 or c3. The question that I have is how would you fix/solve the problem?
the house was a relatively new build as well so how did it pass initial verification?
Discuss.....
 
That’s correct - the tails were unprotected - just run directly from the dno fuse to meter then long run into fuseboard
No there was a switch fuse in a separate cabinet, the issue was that the tails are potentially unprotected in the wall but for all he knows they could be mechanically protected, a limitation in my opinion, you can’t possibly know how they are installed
 
No there was a switch fuse in a separate cabinet, the issue was that the tails are potentially unprotected in the wall but for all he knows they could be mechanically protected, a limitation in my opinion, you can’t possibly know how they are installed
Let’s just assume they are unprotected in the wall for the sake of argument. The question I have is how would you correct the problem?
 
Let’s just assume they are unprotected in the wall for the sake of argument. The question I have is how would you correct the problem?

If the problem is that they are unprotected then the solution must logically be to protect them.

Dig them out and install a heavy gauge metal plate over them would be one soloution, and possibly ideal from an electrical point of view, but not so ideal from the customer point of view.
 
That’s what I thought too but how / where would this be installed. I’ve never had this problem yet Myself but wondered how I would resolve it in the most efficient way.

You can't really as then you'd be putting the whole installation under a single RCD, which is not compliant with section 314.
Another method from 522.6.204 would have to be considered if the cables were less than 50mm deep.
 
Put in the smallest fuse board (4 way?) and take it from/to the db.

If it's feeding the install then have the new enclosure with RCBO (or RCD & MCB) at the servicehead other have it off the main board by a suitable sized RCBO.

I'm probably wrong in my ideas but I'm happy to be properly guided.
 
Time delay RCD won’t comply if it’s for additional protection (which it is).

Your options are protect the cables in the wall with a thick metal plate that can’t be drilled through with sds

or

Replace meter tails with swa
Both options require you to have a switchfuse at the intake position. You can’t rely on DNO’s fuse at that length

Fitting an RCD won’t comply as you risk losing the whole installation in the event of a fault.
 
Time delay RCD won’t comply if it’s for additional protection (which it is).

Your options are protect the cables in the wall with a thick metal plate that can’t be drilled through with sds

or

Replace meter tails with swa
Both options require you to have a switchfuse at the intake position. You can’t rely on DNO’s fuse at that length

Fitting an RCD won’t comply as you risk losing the whole installation in the event of a fault.
There’s a switch fuse at the origin, that’s not the concern
[automerge]1593329691[/automerge]
As the inspector it is impossible to say for certain that the tails are installed incorrectly, cables concealed in the fabric of the building cannot be inspected and are a limitation on the report, as it’s already written for you.
 
Just curious - something like this is a suitable Switched fuse?

and then ideally you would use SWA?
 
There’s a switch fuse at the origin, that’s not the concern
[automerge]1593329691[/automerge]
As the inspector it is impossible to say for certain that the tails are installed incorrectly, cables concealed in the fabric of the building cannot be inspected and are a limitation on the report, as it’s already written for you.
I Understand that and it would be an easy out for the inspector by putting a LIM, however, in this case we are assuming that we already know the cable is unprotected - it may even be a job being picked up following an inspection. My question is all about how to fix the already identified problem.
i haven’t yet had this problem myself and when I thought about it all I could come up with is to fit a small switched fused 100amp unit after the meter or isolator if there was one? Would we then still need to replace the tails? If so, how if the consumer unit is at the other end of the building?
 
My understanding is an Isolator would not be correct for tails over 3m it would need to be a fused.

but it might be better to add a consumer unit at source and this as second CU in SWA also giving Earth fault protection by RCD yes it take out all circuits in Earth fault but would still be safer.
[automerge]1593332022[/automerge]
Skip that stick to a Fused isolator at source > SWA > Consumer unit

a RCD at the other end (not source ) protecting the SWA is that possible?
 
Last edited:
Swa does not require fault or additional protection by an rcd in TN arrangements, buried in a wall or not.
A switch fuse for a distribution circuit to a CU over 3 meters is all that’s required.
Which would probably be a much easier option - and cheaper for the customer too.
The extra question is - how did this get signed off in the first place. I’ve heard it happens regularly - this being a property less than 10’years old so 17th edition regs - they still required this protection didn’t they?
 
New posts

Reply to How do we solve the long meter tail problem? in the Electrical Forum area at ElectriciansForums.net

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top