Manator
©Honorary Essex Boy™
Yes I understand what the regulations say, but the max imposed Ra I am talking about could be 20 or even less.
3phase tt supply setup
- Thread starter Lee321
- Start date
Help Support Talk Electrician Forum:
[quote name='Lee
Manator
©Honorary Essex Boy™
I come across this often in the design specs, some machinery manufacturers have strict max Zs times and void the warranty if they find it has been installed with more than what they say.
green-hornet
Distinguished Member
- Joined
- Feb 25, 2009
- Messages
- 3,741
- Reaction score
- 0
See post 5 for the correct answer
Lee,
It is difficult to match your staccato answers up with the questions in previous posts for continuity and clarity, could you please expand on them or quote the questions?
It is difficult to match your staccato answers up with the questions in previous posts for continuity and clarity, could you please expand on them or quote the questions?
will do next time side apologies.
to fragmented now to compile
---------- Post Auto-Merged at 22:24 ---------- Previous post was made at 22:16 ----------
Q. RA could not be determined until rod installed. ?
no one will be specifying a particular Ra for specialised equipment etc
to fragmented now to compile
---------- Post Auto-Merged at 22:24 ---------- Previous post was made at 22:16 ----------
Q. RA could not be determined until rod installed. ?
no one will be specifying a particular Ra for specialised equipment etc
You can assess ground conditions as has been suggested.
Also as the rod is installed you can monitor Ra to see what your prospective final reading will be.
Also as the rod is installed you can monitor Ra to see what your prospective final reading will be.
Ok so I was feeling I was a million miles away but now that sounds pretty as most would do it. I.e. at site level and confirming earth conditions after install, that's not to say that wack a Rod in and wrap up. It would need testing as it's sent in. Yes specified Ra is something I've never come across before.
Yes, you have, but not realised it.
There are specified Ra values in 7671...
We put a rod in today, hit it in about 1' got about 179 ohms, Ra, we thought, should be OK, in all the way just over 100 ohms, decided to add a 2nd on top, got down to less than 40, wanted 20, but, the last 1' or so was hard going.
So decided to leave it.
We will assess it in dry weather and if it rises too much we'll drop a 2nd rod in parallel the same length to see what we get.
5/8" rod, would never use a 3/8" to be honest.
There are specified Ra values in 7671...
We put a rod in today, hit it in about 1' got about 179 ohms, Ra, we thought, should be OK, in all the way just over 100 ohms, decided to add a 2nd on top, got down to less than 40, wanted 20, but, the last 1' or so was hard going.
So decided to leave it.
We will assess it in dry weather and if it rises too much we'll drop a 2nd rod in parallel the same length to see what we get.
5/8" rod, would never use a 3/8" to be honest.
testing Ra
I'll let you into an easy method of testing it,
now, if you dont understand this please ask with the bits you dont grasp.
I can do you some more diagrams, but TBH they are probably a bit too basic for you, and are more suited to the student and learning zone.
I'll let you into an easy method of testing it,
now, if you dont understand this please ask with the bits you dont grasp.
I can do you some more diagrams, but TBH they are probably a bit too basic for you, and are more suited to the student and learning zone.
