Tt system

[cliffed]

Instaled swa cabling to 2 portacabins,made it tt system,all cabins r tested wiv usual rcd ctrl DBs,problem wiv the Ze offa the earth electode,the measured resistance was 275 ohms,iee recommends max 200 ohms,wot wud you guys do,by the way its a temporary installation cheers men ta ra bab

 

[jaresquire]

Go bigger and deeper?

 

[Guest123]

Depth is key.

1 3/8 rod is nowhere near sufficient in most cases, a few 5/8 rods screwed together in sets of two or three is where you need to start.

 

[cjp1]

Short and thin easy to bang in but long and thick should do the trick.

 

[Dan23584]

I have had a similar issue and as the other guys have said, bigger and deeper does it.

 

[Engineer54]

Instaled swa cabling to 2 portacabins,made it tt system,all cabins r tested wiv usual rcd ctrl DBs,problem wiv the Ze offa the earth electode,the measured resistance was 275 ohms,iee recommends max 200 ohms,wot wud you guys do,by the way its a temporary installation cheers men ta ra bab

Doesn't matter whether it's temporary or permanent, as the responsible electrician you have to provide a reliable working earthing system. So if the ground is good, try 3 x 1.2m 5/8'' rods Do not totally rely on the RCDs.... Some protection, is better than no protection at all!!!

And even at an Ra of 200 ohms, you haven't got any such protection. You want an Ra as low as you can get!! It's about time this ridiculous 200 ohm limit is scrapped once and for all...lol!!

 

[Inteificio]

**** on the rod ;-)

 

[WDMDL]

How about a totally unrealistic spec of 4 Ohms for a remote apparatus case on an IT supply?

Rod farms, mats, you name it - we tried it... including the suggestion above!
The odd few out of thousands got below 10 Ohms!

Mr Furse loved us lol

Simon.

 

[Engineer54]

If you can't get below 10 ohms on a rod farm, your doing something Very wrong!!! Unless they were all 1mt 3/8'' rods ...lol!!