Paul,

I just wanted to tell you that I received the package of Catalogs you sent me and to thank you. I haven't had much chance to look at them yet, but I will and will post anything I find interesting here. If you have any specific suggestions I can do that too. I have a Scanner here.

Have a nice weekend!


Bill

You're most welcome. I'll see if I can give you a few suggestions. Most general fittings will be found in both catalogs; the following refers to the TLC "Contact" catalog:

Pg. 11 6242Y Twin & earth cable.
Our equiv. to Romex, like the sample I sent.

Pg. 21-26 Typical 13A recepts., switches etc. of various makes.

Bottom of pg. 35. These are the type of junction boxes most commonly used in domestic work - the types with brass screw terminals as we discussed a while back.

Top of pg. 54. Typical "consumer unit" (i.e. main panel) used in homes. These Wylex panels have changed very little in over 40 years & remain popular because they can be fitted with rewireable fuses, cartridge fuses, or C/Bs, all shown below.

Panels of more modern design which are common in residential, try pg. 53, 55, 57.

That should be enough to be going on with for now!

Paul,

Just thumbing through the Catalogs here and happened to come across "Earth Rods" The only length I saw was 4 feet long.
Are these what are used for Services over there? I would've thought with your descriptions of "Ungrounded" systems that you would have a longer rod than that.

Do you get the "I Love Lucy" show over there?
(could you please 'splain'?)


Bill

Sure do. It comes around every so often for a re-run, along with Bilko, Star Trek, Happy Days, and the other old favorites. (Don't expect anyone here to have heard of "Gilligan's Island" thuugh.) Anyway, I shall 'splain' - Have to be English though because "Yo no hablo Espanol."

Longer earth rods were quite common in the past, and they're still available, but 4 ft. is pretty much the norm for residential services now.

The current IEE Regs. allow for an electrode resistance of up to 220 ohms. With PME and the old armor-earthed systems the ground-fault path is metallic. With a rod for grounding, there will almost always be a whole-house RCD (GFI).

I gather from some other posts that 8 ft. is standard there and the NEC specifies a maximum of 25 ohms. Correct?

8' electrodes are the minimum buried depth. So if some is to be left exposed, 10' rods must be used.

The 25 ohm rule applies if only one electrode is used. If it is not <=25 ohms, then a second rod is required. But whether they are 250 ohms or 2500 ohms does not matter.

If a 2nd rod is required, does the NEC make any specifications about distance between the rods?

Paul,

If a second rod is used they must be a minimum of 6 feet apart.

Bill

Sorry to throw this one back up Paul, but I couldn't believe the 4ft Earth Stake.
Is this true?.
Ours are at least 6 foot here.

Yessir...'tis true Trumps

We can use any type of 'earth electrode' ( rods, pipes, plates, tapes, wires, as well as u/g structural metalwork in foundations or welded re-bar in conrete ) and the recommended EFLI shouldn't exceed 200 Ohms.

4' is a handy length for a Cu rod if you're driving by hand. Around my area you'd be lucky to get 4" in the ground! I use threaded rods; you can join them up and drive through to Oz if you want to get the figs down - or alternatively just daisy-chain them. I used to drive with a mallet, I now have a handy gizmo for the SDS-Max drill that thumps them in with no effort - too easy in fact!!

John,
So that's what's coming up through my Driveway!.

Yep, round my way the soil is rather sandy (well, the beach is only 200 ft. away!) so you can almost push a 4 ft. rod into the ground with your bare hands. Just don't expect a low resistance reading!

D'ya think the 4 foot earth rods got anything to do with the voltage here, not having 120 Volts? Or is it just that we rely on the meaty neutral more?

At least with RCDs you don't usually need to have 16amps or so flowing to earth/ground before something trips!

I think it's probably more the case of our earthing arrangements.

The only time an earth rod is required here is on a TT system, which will have an RCD, or in old installations a voltage ELCB or a current-operated ELCB of at worst about 500mA rating.

In the U.S., it's normal for all services to have a ground rod installed, despite the fact that they are equivalent to what in British terms would be a PME system.

I tend to introduce rods in new works where the PME supply is o/h and there's any risk that the neutral line could be broken - ie if the supply comes on a few spans through a wood or near trees ( which around here is usual!) before grounding.

I think that's an excellent idea, and I've sometimes wondered why BS7671 hasn't specified earth rods on PME systems as an extra precaution.

Paul, in the late eighties, a local NORWEB inspector told me I was being "over cautious and costing the customer more"...

What price a little extra safety eh?