Quizzes & Puzzles0 min ago
Earth Fault
10 Answers
Came across a problem when I was installing a one of those USB sockets in a ring main yesterday. Was using a Martindale ring main tester to check which circuit to switch off -when it showed up an earth fault - not just in that ring main but the whole house.
The house supply comes up from the garage 100yds away though an underground cable. I found the garage( on a separate circuit but supplied form the hasn't got an earth either or his brothers house either as it is run off the same cable - I know this is a dodgy set up but the owner is a **** and prefers to do things himself rather than spend a penny. However, checked all the earth connections at the board and looked all right.
the only thing I could think of is that the cable to the earth rod has rotted - tried to find it but it is buried in swampy water sodden ground outside the shed somewhere. I've told him to put a new spike in - What size rod and Cable size are required ??
I would have thought the house would still be earthed albeit through the water pipes? Told to get a Sparky in but as I said, prefers to do things himself.
The shed is at least 40yrs old and was the only building in the area with a supply at the time it was built. But two houses are now run of the supply cable with two separate meters.
What size of supply cable should that be?
You are probably wondering how the electric company connected it but that was dodgy too.
Hvaen't checked nut I dare say his brothers house is earthed either.
The house supply comes up from the garage 100yds away though an underground cable. I found the garage( on a separate circuit but supplied form the hasn't got an earth either or his brothers house either as it is run off the same cable - I know this is a dodgy set up but the owner is a **** and prefers to do things himself rather than spend a penny. However, checked all the earth connections at the board and looked all right.
the only thing I could think of is that the cable to the earth rod has rotted - tried to find it but it is buried in swampy water sodden ground outside the shed somewhere. I've told him to put a new spike in - What size rod and Cable size are required ??
I would have thought the house would still be earthed albeit through the water pipes? Told to get a Sparky in but as I said, prefers to do things himself.
The shed is at least 40yrs old and was the only building in the area with a supply at the time it was built. But two houses are now run of the supply cable with two separate meters.
What size of supply cable should that be?
You are probably wondering how the electric company connected it but that was dodgy too.
Hvaen't checked nut I dare say his brothers house is earthed either.
Answers
Sounds like a horrendous installation , Woody. Obviously I can't comment on the state of the supply cable, but You can at least make it safer. Make sure the whole house is protected by an RCD... then ... Install an earth rod just outside the house, as close as possible to the position of the consumer unit. Connect with 16mm earth cable. NEVER rely on water pipes....
12:44 Sun 10th Sep 2017
Sounds like a horrendous installation, Woody. Obviously I can't comment on the state of the supply cable, but You can at least make it safer.
Make sure the whole house is protected by an RCD... then ...
Install an earth rod just outside the house, as close as possible to the position of the consumer unit. Connect with 16mm earth cable.
NEVER rely on water pipes. That went out years ago. But... any incoming METAL water pipe should be bonded to the house earth (10mm cable).
It's essential that the external impedance of the earth rod is then measured. It should be no more than 100 ohms.
Make sure the whole house is protected by an RCD... then ...
Install an earth rod just outside the house, as close as possible to the position of the consumer unit. Connect with 16mm earth cable.
NEVER rely on water pipes. That went out years ago. But... any incoming METAL water pipe should be bonded to the house earth (10mm cable).
It's essential that the external impedance of the earth rod is then measured. It should be no more than 100 ohms.