Upgrading TN-S

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nicks electrix

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Hi All

When i worked for a sparky firm i remember the sparkies upgrading the earth on TN-S systems by clamping an earth clamp around the outer sheath of the incoming cable and from there 16mm to MET. Is this right/ legal?

Thanks

 
As far as I know the lead sheath on TNS systems is the earth so that would be the point where the earth was taken to the MET usually plumbed on in any case which would hve been better than a clamp.

 
This has been talked about before ec15 clamps should not be used on lead sheaths of tns cables as they can damage the cable. DNO have fitted them in the past so its not always sparks that have fitted them. I personally take them off if they are not very secure and fit a composite earth pack which is a proper clamp that is fitted by correct tool and cannot damage cable. I have been told that I should not by other members but because I am in EDF area you cannot get them to do much to there network.

 
This has been talked about before ec15 clamps should not be used on lead sheaths of tns cables as they can damage the cable. DNO have fitted them in the past so its not always sparks that have fitted them. I personally take them off if they are not very secure and fit a composite earth pack which is a proper clamp that is fitted by correct tool and cannot damage cable. I have been told that I should not by other members but because I am in EDF area you cannot get them to do much to there network.
So should i ask DNO to upgrade it because it is a 4mm incoming earth at the moment?

 
So should i ask DNO to upgrade it because it is a 4mm incoming earth at the moment?
If its soldered onto the sheath and loop is low enough best thing to do is sleeve conductor at take that to earth block and then take 16mm to your consumer unit from there.

 
There are thousands of them around but they are deemed to crush the sheath onto the cable . A lot of old copper ones round here . But its the Devil's own job to get the DNOs to upgrade their earths these days.

 
I am in EDF area you cannot get them to do much to there network.
Going off on a tangent somewhat from the earth issue, but EDF's response to trouble reports on their network around here seems to be quite mixed and something of a crap-shoot as to whether it's dealt with quickly or not.

Case #1: Neighbor calls to me, smoke billowing from a splice to concentric at the top of the pole just outside his back door. Called EDF, they were here within about two hours to effect repairs.

Case #2: Pole just inside my front fence which has an underground feed from the sub a few yards away and then distributes power both directions along the road. The mountings for the old cast iron cable head finally gave way during some strong winds one night, with all the expected sparks etc. until the head settled into a position where it was being supported by just the incoming cable and tails to the overheads. Called EDF to report it. Took several days before a guy came out just to look at it and said he'd send in a maintenance request. Several weeks passed before a crew rolled up with a bucket truck to do a temporary lash-up with cable ties. Months later, another couple of EDF guys turned up to "assess" what was to be done. It was then almost a year before independent contractors working for EDF showed up to actually do the final repair. Had to have been about 18 months or so in total.

Case #3: Guy wire on the same pole corroded and went out to find it across my driveway one morning. Called EDF, who arrived later the same day to fix it then and there (while the cable head was still lashed to the pole with ties).

 
Going off on a tangent somewhat from the earth issue, but EDF's response to trouble reports on their network around here seems to be quite mixed and something of a crap-shoot as to whether it's dealt with quickly or not. Case #1: Neighbor calls to me, smoke billowing from a splice to concentric at the top of the pole just outside his back door. Called EDF, they were here within about two hours to effect repairs.

Case #2: Pole just inside my front fence which has an underground feed from the sub a few yards away and then distributes power both directions along the road. The mountings for the old cast iron cable head finally gave way during some strong winds one night, with all the expected sparks etc. until the head settled into a position where it was being supported by just the incoming cable and tails to the overheads. Called EDF to report it. Took several days before a guy came out just to look at it and said he'd send in a maintenance request. Several weeks passed before a crew rolled up with a bucket truck to do a temporary lash-up with cable ties. Months later, another couple of EDF guys turned up to "assess" what was to be done. It was then almost a year before independent contractors working for EDF showed up to actually do the final repair. Had to have been about 18 months or so in total.

Case #3: Guy wire on the same pole corroded and went out to find it across my driveway one morning. Called EDF, who arrived later the same day to fix it then and there (while the cable head was still lashed to the pole with ties).
They certainly don't rush. Had customer with emergency repair to tns cable so head was now 3-4 inches short of meter board in mid air. I was doing cu change so while I was there he rang them to get them to come out to finish job. In fairness someone came out the same day to look but the original repair had been done years before. Hopefully someone will turn up eventually to move board down.

 

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