I have been sub contacting to a electrical contractor carrying out work in new builds , they are telling me to run cables from meters to db over 3m, with no over current protection , some runs are 10m plus , I personally have Said run in 25mm swa or put kmf after the meter , what are your thorghts?
Meter tails
- Thread starter Sloan Lec
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DNO's only allow you to use their fuse to protect up to 3m of tails... anything over that needs over current protection.... you may also need to use SWA dependant on the cable run
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I would say theres little point in using SWA unless the route requires it, concealed less than 50mm in a wall etc and you'd still need a switchfuse in order to nicely terminate it (so try and avoid concealing the submain in a wall)
If you go over the length allowed by the DNO (normally 3m) then you need to put in own overcurrent protection, SWA is not an alternative to this, and gives you the added complication of theres no nice way to terminate at the meter,
So if run is over 3m then put switchfuse in (Not SWA)
If concealed less than 50mm in wall, run in SWA and put suitable switchfuse to terminate SWA in (The KMF ones are no good for SWA)
Both may apply, or just one. If neither apply, eg. tails less than 3m not concealed, then use tails directly.
If you go over the length allowed by the DNO (normally 3m) then you need to put in own overcurrent protection, SWA is not an alternative to this, and gives you the added complication of theres no nice way to terminate at the meter,
So if run is over 3m then put switchfuse in (Not SWA)
If concealed less than 50mm in wall, run in SWA and put suitable switchfuse to terminate SWA in (The KMF ones are no good for SWA)
Both may apply, or just one. If neither apply, eg. tails less than 3m not concealed, then use tails directly.
cant comply 433.3.1(iii) & 434.3(iv) if you dont have a fuse / MCB on the cable
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Not being picky, well actually I am but hey-ho, they are not Compliant with current UK regulations. The Regs are NOT a statute law SO non compliance CANNOT by definition be ILLEGAL
JUST SAYING
Just to raise another issue for discussion ...how far does a sub -contractor or an employee for that matter , go , in a situation like this , the electrical contractor who is being paid to wire these houses properly is responsible for his operatives doing stuff correctly . ....Or is he ???
Does the Subbie raise the issue with his employer , who no doubt doesn't want to hear it & may start looking at you as a trouble maker .
Regulations have you by the spheres with domestic meter tails .
Over 3 m and the DNO regs demand you fit your own overcurrent device .
Meter tails in walls must be 50mm deep or more.
if not you need to fit an RCD at the mains along with the overcurrent protection .
Or you run the tails in surface trunking .
I had to do this on the last one , enclosure has an 60A fuse plus 100A switch ........ but they will only connect to the switch below it so two main switches
Does the Subbie raise the issue with his employer , who no doubt doesn't want to hear it & may start looking at you as a trouble maker .
Regulations have you by the spheres with domestic meter tails .
Over 3 m and the DNO regs demand you fit your own overcurrent device .
Meter tails in walls must be 50mm deep or more.
if not you need to fit an RCD at the mains along with the overcurrent protection .
Or you run the tails in surface trunking .
I had to do this on the last one , enclosure has an 60A fuse plus 100A switch ........ but they will only connect to the switch below it so two main switches
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I would like to think that he would be able to raise the issue with the qualifying supervisor of the firm with the contract and expect that the issue would be properly considered / hopefully a site visit undertaken and any issues with the way the work is being carried out would then get highlighted to the relevant contracts manager and suitable changes would be made to ensure the job is compliant. On the flip side, if he raised something that was actually ok, but the subbie thought not, he should be able to get a clear explanaion of why it is how it is, and why that is actually ok, etc............ However, In smaller firms, where the QS duties are on the owner etc, might end up viewing the issue as secondary to profits however!
Not that i know much abou such things, but how have the electrics to these houses got the correct certification if they do not comply, and why do the building regs people not care??
john..
john..
Sharpend
"It Just Is"
Well I remember doing new builds 5 year ago and being told that an SWA sub main can now be fitted without the switch fuse. I raised this with the company director as I was only so subbie. Apparently this had been ok’d with the DNO’s and the electrical industry.
we were supplied with an earth clamp termination for the Swa at the intake cupboard. Similar to this
https://www.cablejoints.co.uk/sub-product-details/street-lighting-charles-endirect/charles-endirect-central-earth-terminal-swa-cables
checked it out with NIC at the time as it was their certs being used and they agreed it was a done deal?
so much for the Regs :C good job they’re not law I guess???
we were supplied with an earth clamp termination for the Swa at the intake cupboard. Similar to this
https://www.cablejoints.co.uk/sub-product-details/street-lighting-charles-endirect/charles-endirect-central-earth-terminal-swa-cables
checked it out with NIC at the time as it was their certs being used and they agreed it was a done deal?
so much for the Regs :C good job they’re not law I guess???
Davethsparky
Well-known member
With the addition of a small adaptable box you can suitably terminate an SWA into a KMF type switchfuse unit.
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True, I should have said the KMF ones cannot natively accodate SWA.
Not sure I'd mess about like that though, after the extra effort of mounting two items, slotting the adapt box for the cores is it really going to be much cheaper than the lewden ones: https://www.superlecdirect.com/p-fs6380100-lewden-100amp-spandn-single-pole-and-neutral-fused-isolator-switch/
You save about £20 on the switchfuse, probably spend a fiver of that on adapt box. So you save £15 on materials but have a bit more messing about to do, if you say it takes an extra 15 minutes at £32/hr billable time thats £8 gone. I'm not sure its all worth it to offer the customer a £7 saving!
Not sure I'd mess about like that though, after the extra effort of mounting two items, slotting the adapt box for the cores is it really going to be much cheaper than the lewden ones: https://www.superlecdirect.com/p-fs6380100-lewden-100amp-spandn-single-pole-and-neutral-fused-isolator-switch/
You save about £20 on the switchfuse, probably spend a fiver of that on adapt box. So you save £15 on materials but have a bit more messing about to do, if you say it takes an extra 15 minutes at £32/hr billable time thats £8 gone. I'm not sure its all worth it to offer the customer a £7 saving!
