Zs with TT system
- Thread starter markymark2406
- Start date
200 ohms is the max for reliability in guidance docs.
The max in the regs 1666 ohms for a 30mA RCD protected socket circuit (50v/0.03A=1666 ohms).
So although the theoretical maximum is above 200 ohms, this should not be exceeded as it is considered unreliable.
The max in the regs 1666 ohms for a 30mA RCD protected socket circuit (50v/0.03A=1666 ohms).
So although the theoretical maximum is above 200 ohms, this should not be exceeded as it is considered unreliable.
200Ω is the guidance max for the earth electrode itself. With no bonds to other services in place.
If you get 200Ω+ at a socket, you need to check on your bonding and investigate improving the Ze of the earth electrode.
PS I hope that is a 30mA RCD, and it is running to spec.
If you get 200Ω+ at a socket, you need to check on your bonding and investigate improving the Ze of the earth electrode.
PS I hope that is a 30mA RCD, and it is running to spec.
Ok so to get a proper correct figure disconnect the bonding to the water and gas (as pictured)?
I think I may get the service provider to see if they can PME the earth but obviously the Ze needs to be below 0.35 for them to do this, if so is the main rcd ok to remain?
I think I may get the service provider to see if they can PME the earth but obviously the Ze needs to be below 0.35 for them to do this, if so is the main rcd ok to remain?
@markymark2406 FFS. You are obviously doing this job and getting paid for it.
You do not have a clue.
With a Zs that high, lets say you remove the RCD. Where do you think the earth fault path will be if there is an earth/live fault?
I hope you have got insurance, you are going to need it.
You do not have a clue.
With a Zs that high, lets say you remove the RCD. Where do you think the earth fault path will be if there is an earth/live fault?
I hope you have got insurance, you are going to need it.
I'm only asking and learning off the answers people give, I'm not touching anything !
- Joined
- 11 Jan 2004
- Messages
- 45,872
- Reaction score
- 3,517
- Country
Numerical spark - it's only 1 ohm, but I thought the regs said 1667, which I think is wrong, as it puts the touch voltage above 50V.
I used to be guided by the 100 Ohm maximum that ECA used to set (don't know if it's still the same).
If you have a reading above 100, investigate it to find out why.
OP - in the earth block at the intake, you have one to the CU and two others - do these go to the service pipes?
You may have a poor earth off the pipework and no earth electrode!
I used to be guided by the 100 Ohm maximum that ECA used to set (don't know if it's still the same).
If you have a reading above 100, investigate it to find out why.
OP - in the earth block at the intake, you have one to the CU and two others - do these go to the service pipes?
You may have a poor earth off the pipework and no earth electrode!
What have you been doing since then? Did you do the T&I course? Did you pass the exam? Or given that you can't even do simple cable sizing calculations or basic maths, was it all too much for you?
http://www.diynot.com/diy/threads/swa-size.174636/
Same Q 8 months later, same "qualified electrician" who can't do cable sizing: http://www.diynot.com/diy/threads/cable-culculations-for-shed.205483/
And another: http://www.diynot.com/diy/threads/outside-heaters.235103/
Same Q 8 months later, same "qualified electrician" who can't do cable sizing: http://www.diynot.com/diy/threads/cable-culculations-for-shed.205483/
And another: http://www.diynot.com/diy/threads/outside-heaters.235103/
But back to asking and learning:
Marky - why ask questions here if you are going to do SFA with the answers you get?
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
