Grounding a new build for a novice

[TravelerEastWest]

Grounding a new build for a novice (I am the novice - not the electrician - hopefully)

A good friend told me the other day:

1) Ground rods in the ground under the house (not sure how many or how deep)

2) Connect the rods to the metal in the concrete slab

3) Connect the metal in the concrete slab to the metal in all the columns

4) Connect the metal in the columns to all outlets.

Do I understand the basics or am I way of?

If you have a link to a good tutorial in plain English that would be great!

As a side note I think that I own a Toshiba refrigerator bought in Thailand about 6 years ago with only a two prong plug.

[IMHO]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

I have never heard of implementing a ground via the house frame, and given the poor electrical qualities of tied rebar, wouldn't recommend it. It could very well create a quasi faraday cage and kill your cellphone and wifi signals doing it that way though - maybe your friend wears tin foil hats?

Edited October 27, 2013 by IMHO

[Crossy]

+1 IMHO

What your friend proposes would not be acceptable to PEA and could introduce shock hazards, I'm not aware of any electrical code that permits the use of structural steel as a ground path from individual outlets.

Using the structural steel as a main ground is possible (Google "Ufer ground") but needs the main re-bar segments to be welded (not tied) and I'm not sure how MEA/PEA would react to one in a domestic installation, far better to use the classic rod linked directly to the ground bar in the consumer unit

This PEA document http://www.crossy.co.uk/Handy%20Files/groundwire.pdf (sorry it's 15MB) will tell you and your sparks everything you need to know. It's in Thai, but lots of pictures so you should get the idea, post here if anything is unclear.

Note the correct Thai routing of the incoming neutral (via the ground bar), this implementation of MEN is the same as specified by the US NEC and will be required for MEA/PEA to pass your installation inspection.

Whether you tie your structure to the power earth is up to you, our steel is well grounded (very wet Bangkok clay) in fact, from the roof trusses it measures rather better than our rod, so I've tied the steel to the rod at a single point to guarantee no possibility of potential between appliances and the structure.

If you don't use an exothermic weld to secure the cable to your rod you need to ensure the clamp remains accessible for checking.

[Mrjlh]

Crossy...two interesting articles or links on the subject that you should mull over and maybe would help the OP also.

http://www.garagejournal.com/forum/showthread.php?t=92184

http://forums.mikeholt.com/showthread.php?t=104493

[Crossy]

Crossy...two interesting articles or links on the subject that you should mull over and maybe would help the OP also.

http://www.garagejournal.com/forum/showthread.php?t=92184

http://forums.mikeholt.com/showthread.php?t=104493

Interesting indeed, but it's important to note that the NEC does not apply in Thailand and Ufer grounds are not allowed for in any of the (limited) domestic wiring documentation I've seen.

Mind you, industrial installations are a whole different kettle of fish sauce.

In order to avoid issues with the PEA inspector bash in a rod and connect it to the ground bar.

[TravelerEastWest]

Thanks all,

Step one cancel my friends idea

Step two I have printed out the downlaod

Step three study the photos

Step four find a Thai speaker to help me.

[Sophon]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

<snipped>

Any special requirements for the thickness of the wire between consumer unit and ground, and would more than one ground rod be recommended?

Sophon

[Artisi]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

<snipped>

Any special requirements for the thickness of the wire between consumer unit and ground, and would more than one ground rod be recommended?

Sophon

Just in case you don't get any response, there are rules and regulations regarding wire size and multiple ground rods, but not my area of expertise so won't comment - but you need to check it out.

Edited October 28, 2013 by Artisi

[kannot]

stick the ground rod near your septic tank if you have one it needs moist soil.

[TravelerEastWest]

 

stick the ground rod near your septic tank if you have one it needs moist soil.

 

That will be easy we will have two septic tanks - thank you for the advice.

[wayned]

stick the ground rod near your septic tank if you have one it needs moist soil.

If they are true septic tanks, the soil will not be moist as they are totally enclosed and do not leach into the soil. Is you are talking about a Thai "cesspit" then yes the soil will be moist if it is working correctly.

[Crossy]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

<snipped>

Any special requirements for the thickness of the wire between consumer unit and ground, and would more than one ground rod be recommended?

Sophon

The wire needs to carry the trip current of your incomer and be sufficiently robust to prevent accidental damage.

Ours is 10mm² on a 50A incomer, adequate in both respects. The PEA inspector was happy

Nothing in the regulations (such as they are) preventing multiple rods. I would note however that multiple rods are not permitted in Australia due to the possibility of lightning induced ground currents passing between the rods via the link cable. Since we are also in a lightning prone region I would avoid multiple rods unless you cannot get a decent earth with only one (in which case an Ufer using the building steel would probably work better than a second rod).

[IMHO]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

<snipped>

Any special requirements for the thickness of the wire between consumer unit and ground, and would more than one ground rod be recommended?

Sophon

I'm not sure on the actual regulations, but we use 6mm green THW to the load centre, then 2.5mm again to the power outlets, 6mm to water heaters, and 4mm to AC, and have never had any issues with approvals. We've even done places with dual load centres sharing the one earth, also no problems with approvals.

All of our installs use RCBO's though, so the ground theoretically only needs to dissipate 30mA I guess.

Note that I'm not an electrician, I've just been semi-involved in the house building process a lot of times

Edited October 28, 2013 by IMHO

[canopy]

This could sort of for electrical geeks, but a UFER ground is attractive because it is simple, compact, and makes a great ground. If Thailand hasn't caught up in their electrical codes you can do both--make a classical ground rod to panel following all Thai specifications, then add an additional wire from rod to UFER. So why do both? Well grounding in other countries is more stringent than Thailand for safety and the fact households pull much higher loads. Where in Thailand you may see one little rod placed arbitrarily, in the west you may see 8 rods in key areas linked together each well over 2 meters long of solid copper attached using special acorn clamps suitable for burial. And now UFER is such a good ground it is quickly becoming a requirement for new builds as it is better than the rod system. So attaching a ufer to a Thai style rod can enhance the ground to a very high quality--if you care, and most here won't. Following NEC (USA) specifications for UFER, no rebar welding is needed, but you must attach to rebar something like at least 20' long, there must be 2 contact points, and special clamps are needed which I doubt you will find in Thailand.

[h90]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

I have never heard of implementing a ground via the house frame, and given the poor electrical qualities of tied rebar, wouldn't recommend it. It could very well create a quasi faraday cage and kill your cellphone and wifi signals doing it that way though - maybe your friend wears tin foil hats?

Maybe to add: here they twisted the wires together, with corrosion it is not good enough for ground (in my opinion).

I soldered the ground wires together, because lack of some good quality clamps (or however these are called in english to connect wires)

[kannot]

stick the ground rod near your septic tank if you have one it needs moist soil.

If they are true septic tanks, the soil will not be moist as they are totally enclosed and do not leach into the soil. Is you are talking about a Thai "cesspit" then yes the soil will be moist if it is working correctly.

If they are true septics there will be two tanks the second being the one to bang the rod down close to as this should be open to the gorund the first being totally waterproof with and enclosed sealed bottom section not an open ring.

The left one in the picture is sealed and overflows into the right one ( liquids only) to drainfield area

Edited October 31, 2013 by kannot

[IMHO]

The normal way is:

Ground rod to the load centre (AKA consumer unit) via copper THW wire > then load centre to outlets via copper THW.

I have never heard of implementing a ground via the house frame, and given the poor electrical qualities of tied rebar, wouldn't recommend it. It could very well create a quasi faraday cage and kill your cellphone and wifi signals doing it that way though - maybe your friend wears tin foil hats?

Maybe to add: here they twisted the wires together, with corrosion it is not good enough for ground (in my opinion).

I soldered the ground wires together, because lack of some good quality clamps (or however these are called in english to connect wires)

If they have twisted wires together, it's a bad wiring job. From the ground rod it should go to a bussbar in the load center, then out from that bussbar to each outlet (as a straight run). If you see your electrician using junction boxes in the ceiling and twisting wires together, either show them how it's not too much work to use straight, join-free wire runs, or find a better electrician

It only takes around 3000 watts for a few minutes to start melting a soldered connection @ 220VAC. My pressure washer and stereo system have melted connections in every soldered power board they've been connected to

Edited November 1, 2013 by IMHO