uksparks
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Hi,
Sorry about the quality of the photos, it was very dark in the garage.
Went to a job this morning, to quote on a new consumer unit, see photos below.
It's a TT earthing system, 8 way 3036 board, needs new bonding etc. Main earthing conductor is only 6mm at present, rod is just outside the garage against the wall, no idea how big it is yet.
Its got an overhead supply, two phases, but only one is used.
All the old junk on the right is coming out as its not used, this was on the second phase, it was for storage heaters.
Ill be quite honest, I have never done a TT before so would like a few pointers.
I'm going to replace the board for a split board, thats not an issue, its just the earthing thats the issue.
I did a Zs at the board just to see what the readings were like and you can see the photos below.
A couple of questions...
1. being a TT, i understand it needs an upfront RCD? Yes? 300ma?
2. I took a PSCC and PEFC reading and the PEFC was a lot lower than I had expected and want to know if its normal so to speak, obviously the fault current comes down the higher the resistance.
3. Im permitted 200 Ohms on Ze, so 8.3Ohms is good.
This was with the earth connected, it was only a brief look, so not an exact measurement.
PSCC (L - N)
0.19 Ohms
1.3kA PFC
PEFC (L - E)
8.33 Ohms
30A PFC
Is there anything I should have to think about it addition to the norm with a TNC-S / TNS supply? I can't think of anything other than the RCD.
I felt the 30A was low on the PEFC, but then again, its got an RCD.
I can only assume this was an RCD as it tripped when I did a high current Zs on the board.
Miscellaneous...
Sorry about the quality of the photos, it was very dark in the garage.
Went to a job this morning, to quote on a new consumer unit, see photos below.
It's a TT earthing system, 8 way 3036 board, needs new bonding etc. Main earthing conductor is only 6mm at present, rod is just outside the garage against the wall, no idea how big it is yet.
Its got an overhead supply, two phases, but only one is used.
All the old junk on the right is coming out as its not used, this was on the second phase, it was for storage heaters.
Ill be quite honest, I have never done a TT before so would like a few pointers.
I'm going to replace the board for a split board, thats not an issue, its just the earthing thats the issue.
I did a Zs at the board just to see what the readings were like and you can see the photos below.
A couple of questions...
1. being a TT, i understand it needs an upfront RCD? Yes? 300ma?
2. I took a PSCC and PEFC reading and the PEFC was a lot lower than I had expected and want to know if its normal so to speak, obviously the fault current comes down the higher the resistance.
3. Im permitted 200 Ohms on Ze, so 8.3Ohms is good.
This was with the earth connected, it was only a brief look, so not an exact measurement.
PSCC (L - N)
0.19 Ohms
1.3kA PFC
PEFC (L - E)
8.33 Ohms
30A PFC
Is there anything I should have to think about it addition to the norm with a TNC-S / TNS supply? I can't think of anything other than the RCD.
I felt the 30A was low on the PEFC, but then again, its got an RCD.
I can only assume this was an RCD as it tripped when I did a high current Zs on the board.
Miscellaneous...
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