TT system main bonding CSA?

[Farmelectrics]

Interesting reading but I'm lost so what is the max value 21 ohms or 200 ohms

 

[shanky887614]

Not installed many earth rods then shanky? Lol

1/2" is closer to 13mm and 5/8 is more like 16mm

installed? no

i havent even seen one, i dont do any domestic and rarely do power from ccu either, usually from control panels.

i have done a couple boards but not many


but i do know enough about them that i could install one correctly (in earth put )and test it

 

[Falcon Flyer]

Were they SPSN RCBOs or are they the standard SP RCBOs which are commonly available?

Was the person who told you that 2 rods is dangerous certified as insane or something? The whole country would be in serious trouble if this was the case!

Yes, it was on my last refresher course. The instructor did indeed state that he'd seen a few remote farm buildings where the installer had supplied another earth rod in order to make the disconnection times work. His point was that they should have been wired as two separate jobs, with individual earthing, not two rods connected on the same system. That way any fault would only go to ground at one location.

Can an overhead supplied TT system be upgraded to PME?

 

[telectrix]

good point two inch holesaw is 51mm XD my bad 1"=25mm

1 ft. = 12".
3ft. = 1 yard,
22 yards = 1 chain
10 chains = 1 furlong
8 furlongs = 1 mile
1 rod = 5.5 yards
4 rods = 1 chain

there are 20 fluid ounces in a pint. 2 pints make 1 quart. 4 quarts make 1 gallon. that's a serious beer session.

here endeth the lesson.

 

[trev]

Change your instructor.

 

[shanky887614]

1 ft. = 12".
3ft. = 1 yard,
22 yards = 1 chain
10 chains = 1 furlong
8 furlongs = 1 mile
1 rod = 5.5 yards
4 rods = 1 chain

there are 20 fluid ounces in a pint. 2 pints make 1 quart. 4 quarts make 1 gallon. that's a serious beer session.

here endeth the lesson.

id be on my backside after 3 quarts, i couldn't stomach a galon (i dont drink more than 2-3pints of water a day usually anyway

 

[davesparks]

installed? no

i havent even seen one, i dont do any domestic and rarely do power from ccu either, usually from control panels.

i have done a couple boards but not many


but i do know enough about them that i could install one correctly (in earth put )and test it

Earth rods aren't limited to domestic work!

Have you done an earth rod test before then? It is something which seems to be missing from a lot of electricians knowledge, they can just about do the Bodgeit method with a loop tester, but many don't even know what a 3 wire fop test is!

 

[telectrix]

Ra values can be improved ( lowered ) by the application of a pint or 2 of ale. the ale must be processed in the established manner before applying to the soil surrounding the rod. the first step is to drink the ale and then wait for the prescribed length of time, by which time nature has processed the ale, and you then apply it.

 

[shanky887614]

Earth rods aren't limited to domestic work!

Have you done an earth rod test before then? It is something which seems to be missing from a lot of electricians knowledge, they can just about do the Bodgeit method with a loop tester, but many don't even know what a 3 wire fop test is!

nope, most work is bms. power to our panels is usually done by others as well.

yes the earth rod test is using 3 leads connected

basically this in osg

 

[davesparks]

Yes, it was on my last refresher course. The instructor did indeed state that he'd seen a few remote farm buildings where the installer had supplied another earth rod in order to make the disconnection times work. His point was that they should have been wired as two separate jobs, with individual earthing, not two rods connected on the same system. That way any fault would only go to ground at one location.

Can an overhead supplied TT system be upgraded to PME?

Nonsense! A single earth rod is far less effective than 2 in parallel! On a farm I would be looking to install a rod at each building and have them all linked together through the cpcs.
The more deep rods you have the better and more stable your Ra will be.

Installing them correctly will prevent potential gradients appearing on the ground.

Yes the DNO can convert their TT supplies to PME, if they have done this you can apply to have a PME connection made at the property.

Go and have a look at the overhead lines to see if they have done so in your area.

 

[davesparks]

Interesting reading but I'm lost so what is the max value 21 ohms or 200 ohms

There is no max stated value, they have left it up to the electrician to make an informed decision using their knowledge and experience!

 

[Farmelectrics]

How would you no if they've converted it to a pme by looking at the overhead lines surely they just install a pme head

 

[telectrix]

every 3rd or 4th pole will have an earthing arrangement.

 

[Farmelectrics]

Ok tel I see but they could just put the link in at intake and have just a tnc- s system am I right

 

[davesparks]

How would you no if they've converted it to a pme by looking at the overhead lines surely they just install a pme head

No they don't just install a PME head, they have to ensure that their network complies with the requirements for PME first.

They have to have N-E connections via earth electrodes at set distances along the entire length of the main, along with an electrode at the furthest point of the main (or furthest points if it branches)

In this area every pole with a N-E connection has a white label with PME in red letters fixed to the pole.

Also the use of ABC cable suggests that PME is likely to be available.