SWA earth leakage?

[madkayaker]

The damage of the Neutral leaking to earth is if the conductor was to fail the all the current would flow to earth and could raise the potential (and there for voltage between earth and the ground if that makes sense!) also the earth could provide a lower resistance return path then the neutral and there for would take all the current with the above effect. an RCD will trip if neutral and cpc are shorted always a good one to frighten apprentices with when the cut the cable (that is de-energised) and the lights go out!

 

[Woody.v8]

Cheers mate, Not the news I wanted but "the jobs got be rate"
So if I cant find anything up with the glands tomorrow I will get the spade out
And this time lay some 125mm duct

 

[madkayaker]

It's possibly a long shot but check where the cable goes into the ground for damage I have seen it where thee has been a bit of movement and it's rubbed there. Another thing is carefully use a heat gun and try to dry out the cable near the gland especially if water has got into the gland. If you do change the cable put it in a duct!

 

[Woody.v8]

It's possibly a long shot but check where the cable goes into the ground for damage I have seen it where thee has been a bit of movement and it's rubbed there. Another thing is carefully use a heat gun and try to dry out the cable near the gland especially if water has got into the gland. If you do change the cable put it in a duct!

I said in an earlier post that id used heat near the incoming fuse end and the resistance reduced.
And as for the duct LESSON LEARNT

 

[madkayaker]

The resistance is needing to increase so lower current flows.

 

[Woody.v8]

The resistance between Earth and L3?

 

[madkayaker]

That's it the resistance wants to be as high as possible. But as your getting the reading with the multi meter with the proper tester it will be shot

 

[Woody.v8]

That's it the resistance wants to be as high as possible. But as your getting the reading with the multi meter with the proper tester it will be shot

Ok Mk

 

[the snooper]

if its water in the cable get the national grid guys they connect a box at the fuse board and boil the water out if that dont work they dig.
moisture repelant will be no good for moisture in a cable you cant flush the water out it will still sit there along with he repelant

 

[Woody.v8]

if its water in the cable get the national grid guys they connect a box at the fuse board and boil the water out if that dont work they dig.
moisture repelant will be no good for moisture in a cable you cant flush the water out it will still sit there along with he repelant

Boiling the water out you say..umm, I wonder how that works?

 

[awemawson]

Using a low voltage transformer I'd imagine they pass a huge current down the cable to warm it up. I've heard reports that in the big freeze up in the 1960's when water house feeds were often copper pipe the water board would thaw them using a welding transformer connected to the stop cock at both ends

 

[madkayaker]

However you might melt the conductors in the cable then your no better off! national grid cable is very different stuff to swa

 

[pidgeon chit welder]

Something tells me to ask have you got a modern fridge or freezer outside the house in the building /s supplied by the SWA .. ?
Modern stuff tends to take/ make moisture in wet weather /damp conditions and gives earth type faults if it is outside.
Your protection box may also be sensing leakage from someone close by who has faulty equipment .

We have had a complete rewire , whilst it sorted out some proplems I had to get the protection to the garage SWA changed for the very reason of it tripping when the next door used their washer ( It showed earth leakage ) but was not tripping her unit that was nearly 30 yrs old .

Since my unit has been changed I've not had another trip out in 2 & 1/2 years.

I have also experienced a dirty incoming mains at another premise .. for years I kept complaining that my fuse board kept tripping out despite having all the circuits disconnected .. Only after threatening the electric board with going to Auntie Ester Rantzen did they do anything and ran a full strip / isolate and reconnect to make sure it was not my side of the meter . It passed 100 %.. Whilst the higher techs came they witnessed 40 odd trip outs in under half an hour but couldnt understand till I mentioned the quality of supply contract and asked them to bring a dual beam oscilloscope instead of the cylinder recorder they were leaving hooked up for 24 hrs.

Two days later they came back checked the recorder which showed everything OK , then they put the scope on the mains & froze a few snap shots only to find that I was getting hit by massive spikes of several mili seconds .

Next day they had a team come and renew from the pole into the meter and fitted a new protection device that had a big fat mains filter built into it .
That sorted things out there & then ... asking how I knew about the dirty mains thing , I told them I was a city & guilded electronic test and service mechanic in a former life and had studied HND electrical engineering for a while .

A few day later the local pole transformer was also replaced as part of the same repair session .

 

[the snooper]

Using a low voltage transformer I'd imagine they pass a huge current down the cable to warm it up. I've heard reports that in the big freeze up in the 1960's when water house feeds were often copper pipe the water board would thaw them using a welding transformer connected to the stop cock at both ends

nope not a transformer i was in a substation 4am with one of the guys and the box called a zapper i think wasnt heavey enough to be a transformer of that type i did search for it but found nothing

 

[madkayaker]

Something tells me to ask have you got a modern fridge or freezer outside the house in the building /s supplied by the SWA .. ?
Modern stuff tends to take/ make moisture in wet weather /damp conditions and gives earth type faults if it is outside.
Your protection box may also be sensing leakage from someone close by who has faulty equipment .

We have had a complete rewire , whilst it sorted out some proplems I had to get the protection to the garage SWA changed for the very reason of it tripping when the next door used their washer ( It showed earth leakage ) but was not tripping her unit that was nearly 30 yrs old .

Since my unit has been changed I've not had another trip out in 2 & 1/2 years.

I have also experienced a dirty incoming mains at another premise .. for years I kept complaining that my fuse board kept tripping out despite having all the circuits disconnected .. Only after threatening the electric board with going to Auntie Ester Rantzen did they do anything and ran a full strip / isolate and reconnect to make sure it was not my side of the meter . It passed 100 %.. Whilst the higher techs came they witnessed 40 odd trip outs in under half an hour but couldnt understand till I mentioned the quality of supply contract and asked them to bring a dual beam oscilloscope instead of the cylinder recorder they were leaving hooked up for 24 hrs.

Two days later they came back checked the recorder which showed everything OK , then they put the scope on the mains & froze a few snap shots only to find that I was getting hit by massive spikes of several mili seconds .

Next day they had a team come and renew from the pole into the meter and fitted a new protection device that had a big fat mains filter built into it .
That sorted things out there & then ... asking how I knew about the dirty mains thing , I told them I was a city & guilded electronic test and service mechanic in a former life and had studied HND electrical engineering for a while .

A few day later the local pole transformer was also replaced as part of the same repair session .

At work we had a trip on the 11kv the other month that was caused by the electric board closeting the breaker onto a faulty cable 3 miles away! The reason modern circuit protection gives some nauscence trips is the old stuff was so poor at providing protection anything short of cutting hate cable would not operate it