Earth cable from earth rod to consumer unit?

[Cashboy]

I am using the 50 Amp single fase government supply.

 

I am using 16mm copper wire for live and neutral as soon as those 25mm aluminium cables enter the roof of the house.

 

I have my 2.4 meter rod ready to bang into the ground.

 

What size of cable (copper) do I need to go from this rod to the consumer unit.

 

I thought it would be 16mm copper as well, but am sure that I have read that it can be 10mm?

If this is the case, why would it be smaller than the live and neutral?

 

 

 

 

[stouricks]

It will not be smaller if YOU use 16mm.

[Crossy]

With 30mA earth leakage protection it could actually be as small as 1.5mm2!!

 

But, we don't do that.

 

10mm² is generally the smallest recommended for protection from physical damage, if you have some spare 16mm² that would do the trick.

 

By the way, I would put the Al/Cu splice outside the roof space, if anything is going to fizz that's it and it's best fizzing outside ????

 

The reason you can use a smaller protective conductor pretty much everywhere is simply that it's not a current carrying conductor. L and N are expected to carry the full load current forever and are sized for that purpose. The E only has to carry current until the protective device opens, usually no more than a few seconds, provided it is large enough (low enough resistance) to allow that current to flow and doesn't overheat before the protection operates. 

 

[Cashboy]

32 minutes ago, Crossy said:

 

 

By the way, I would put the Al/Cu splice outside the roof space, if anything is going to fizz that's it and it's best fizzing outside ????

Interesting !!

 

I was using a 100 Mains Switch in a metal box to connect the Al 25mm to Cu 16mm.

 

Would that be OK to use under the eaves of the house outside?

 

 

 

 

32 minutes ago, Crossy said:

 

 

[Crossy]

2 minutes ago, Cashboy said:

I was using a 100 Mains Switch in a metal box to connect the Al 25mm to Cu 16mm.

 

If that switch is rated for Al and Cu cable it will be fine, even in the roof space. I was thinking more of the typical Thai twist and lots of tape "splice".

 

Does it have an IP rating of IP54 or IP65? If not I would suggest that the location you indicate would be too exposed to blown rain.

[Crossy]

Not a lot to catch fire up there ????

 

[Metropolitian]

Edit button taking forever again..

 

In my last post a text is pasted double; It has to be replaced with :

Here it would then give a good fizz right under the roof sheets ????

 

 

For the OP: The arguments posted by Crossy, regarding the earth wiring sizing matter on durability and the IP rating for the outdoor switch unit,

I would say the same so that's two tvf-sparkies already to confirm those statements. ????

 

1 hour ago, Cashboy said:

Would that be OK to use under the eaves of the house outside?

It would be more protected for raindrops if it was mounted in the corner of the balcony, still mind the IP rating as it sits outside and with wet season the air, even protected under roof, is very humid.

I have seen rain going horizontal before. Even slightly going up ! Lifted by winds.

[taninthai]

When you get to consumer unit connections Don’t forget you take your neutral through the earth bar then to main cu breaker.

[Pilotman]

I trained as an electrician back in the dim distant past, very dim and very distant, but the electricity situation in this place terrifies me.  I just leave well alone while its working, while acknowledging that one day, the house is going to try to kill me, one way or another.  

[mistral53]

17 minutes ago, Metropolitian said:

 

Situation has changed a bit, a knife switch is now on the wall.

But the AL/Cu splice still there. Main CU is now right under here.

 

Situation has changed a bit, a knife switch is now on the wall.

But the AL/Cu splice still there. Main CU is now right under here.

 

 

 

 

Is it just me or are you missing the aluminum insulation foil?

[Metropolitian]

2 minutes ago, Metropolitian said:

mounted in the corner of the balcony

 

BTW. Is there a particularly reason you want the main breaker at the balcony?

 

I do have mine in the attic space, which is the 'work-breaker' to kill the elecricity in the house when I am working on the main size of the CU.

The main CU has two main breakers, one for the old part and one for the new part of the wiring in house.

In my old country I has one switchbox outside, with a red handle, and has to be accessible from the ground floor so easily cut off by the fire dep. and I used it when necessary.

 

[Crossy]

6 minutes ago, taninthai said:

When you get to consumer unit connections Don’t forget you take your neutral through the earth bar then to main cu breaker.

 

Yes. Have a read of this PEA document Groundwire Mk2 book-Manual.pdf

 

The important bit with translations.

 

 

[petedk]

28 minutes ago, Pilotman said:

I trained as an electrician back in the dim distant past, very dim and very distant, but the electricity situation in this place terrifies me.  I just leave well alone while its working, while acknowledging that one day, the house is going to try to kill me, one way or another.  

Yes, it takes anything from 3 - 5 years to become an electrician in the UK.

 

Here it takes 3 - 5 minutes at looking at a diagram.

[Crossy]

24 minutes ago, petedk said:

Here it takes 3 - 5 minutes at looking at a diagram.

 

You've seen a Thai sparks with a diagram?

[Cashboy]

I am even more confused today.

Last week I bought 16mm copper cable for the live and neutral and earth.

I was under the impression that I would use 25mm aluminium from the meter on the pole to the house and then go to the 16mm copper.

 

I based all that on the standard government available supply:

 

 

I was under the impression that I would order the 15(45) whatever that is.

I was under the impression from questions on here that it would be a 60 Amp supply even though I don't see any correlation between 15(45) and 60 amp single phase.

Then people on this forum were telling me 16mm copper or 25mm aluminium.

That seemed correct to me because in my UK house I have a 80Amp Mains Fuse and 16mm copper cable to the consumer unit.

 

I then ask people would 3 x 16mm copper fit in 1/2" plastic SCG eletric conduit where you said "no or too tight fit"

I did not want to make the hole through the concrete floor any bigger as it would necessitate cutting a reinforcement rod or steel mesh.

 

When I purchased a roll of the 16mm copper I was able to feed 3 of them in the 1/2" SCG electric conduit.

 

Today I went to Global House to buy some plastic bushes to drill into the mains switch box wondering whether I should put 2 x 3/8" (one for each 25mm aluminium cable) or one x 3/4" to pass through two 25mm aluminium cables (live and neutral).

The guy in the shop then said I should be using 25mm copper and 35mm aluminium mains supply.

I then got my Thai secretary to ask and she was told use 50mm aluminium because safer than 25mm.

This from a country that won't even put a 10 bt light bulb in their motorbike and drive in the dark with no lights.

 

Have the regulations changed and you lot not aware?

Am I hearing miss information from shop workers?

 

All I really would appreciate to know now to be able to do the electrics in my new house is:

What cable size is required for the government regulations and won't burn my house down (difficult as only steel and concrete).

Once I know the cable sizes I shall try to get on with this.

 

 

 

 

 

 

[RichCor]

Interesting that you don't remember asking similar questions Feb 5, 2018.

 

Anyway, in that thread Crossy posted

 

Quote

To check what you have look at the meter, most of us survive on a 15(45), 15A is the calibration current, 45A is the maximum continuous current. That said, meters are incredibly robust and a 100% (90A) overload isn't going to blow it off the wall although the accuracy will be compromised (you can bet it won't read low). Those on a 15(45) will have either a 50A or 63A incoming breaker.

 

And about stuffing mains cable into conduit, while it may fit there needs to be adequate air to aid in dissipating heat and prevent the poly covering from melting when pulling high amps.

[RichCor]

2 hours ago, Cashboy said:

All I really would appreciate to know now to be able to do the electrics in my new house is:

What cable size is required for the government regulations and won't burn my house down (difficult as only steel and concrete).

Once I know the cable sizes I shall try to get on with this.

You may want to review this thread (just ignore the 'underground' options), they discuss Mains Cable Sizes and posted some charts.

 

 

[Crossy]

The people who are going to inspect your installation and give you the permanent meter are the ones to ask about feed cable sizes, PEA (or MEA if you are in Greater Bangkok).

 

But, unless you have a very long run 25mm² Al / 16mm² Cu on a 15/45 meter would seem to be the norm. although this PEA poster suggests 10mm² (green table, centre bottom)

 

 

[Crossy]

8 hours ago, Cashboy said:

Today I went to Global House to buy some plastic bushes to drill into the mains switch box wondering whether I should put 2 x 3/8" (one for each 25mm aluminium cable) or one x 3/4" to pass through two 25mm aluminium cables (live and neutral).

 

If your switch box is metal do not use separate holes for L and N.

 

Although the effect will be fairly small at the currents we are dealing with you will get eddy-current heating of the area between the wires. That's heating power for which you are paying.

 

[Crossy]

8 hours ago, Cashboy said:

When I purchased a roll of the 16mm copper I was able to feed 3 of them in the 1/2" SCG electric conduit.

 

You can "fit" 18 in an old-style VW beetle. That doesn't mean it's OK for normal circumstances. Don't go over 50% fill in your conduit.

 

 

 

[Crossy]

There's a fill-ratio calculator here https://tools.belden.com/conduit-capacity-calculator/

 

21mm I/D conduit (3/4") would give you a fill ratio of 40% with 3 x 16mm² cables (7mm diameter).

 

16mm I/D conduit (1/2")  would give you a fill ratio of 75% with 3 x 16mm² cables (7mm diameter).

 

Because the area is proportional to r² you don't need to go much bigger to get in an acceptable range.

 

As has been noted before, there's no reason why your earth needs to be 16mm², swap for 10mm² and you get a correspondingly better ratio.

[Cashboy]

3 hours ago, Crossy said:

 

9 hours ago, RichCor said:

You may want to review this thread (just ignore the 'underground' options), they discuss Mains Cable Sizes and posted some charts.

 

 

 

 

Thank you for that.

I actually recall reading that post.

 

So 25mm Aluminium or 16mm copper was correct to carry the load and satisfy government.

 

The PEA concrete post on the road where the electric meter will be placed is 15 meters away.

I would say another 6 meters down the post to the electric meter making about 23 metres.

 

Am I better off running 16mm Copper or 25mm Aluminium given the choice?

 

 

 

[Crossy]

1 minute ago, Cashboy said:

Am I better off running 16mm Copper or 25mm Aluminium given the choice?

 

Al will be a lot cheaper and less likely to wander.

 

But for such a short run I'd just run copper all the way. 

[bankruatsteve]

4 hours ago, Crossy said:

The people who are going to inspect your installation and give you the permanent meter are the ones to ask about feed cable sizes, PEA (or MEA if you are in Greater Bangkok).

This is what you really need to do!

[Cashboy]

3 hours ago, Crossy said:

There's a fill-ratio calculator here https://tools.belden.com/conduit-capacity-calculator/

 

21mm I/D conduit (3/4") would give you a fill ratio of 40% with 3 x 16mm² cables (7mm diameter).

 

16mm I/D conduit (1/2")  would give you a fill ratio of 75% with 3 x 16mm² cables (7mm diameter).

 

Because the area is proportional to r² you don't need to go much bigger to get in an acceptable range.

 

As has been noted before, there's no reason why your earth needs to be 16mm², swap for 10mm² and you get a correspondingly better ratio.

Area of a circle  = Pie x Radius Squared.

The old basic maths from school days.

 

I was under the impression it was all about physically fitting in the conduit.

I say that because I managed to get 9 x 1.5mm cables in 1/2" SCG conduit for the lights last week even round those sharp 90 degree bends under the concrete first floor.

 

 

 

 

[Crossy]

It really is entirely up to you what you do.

 

Codes are not rigorously enforced here like the are in the west, but rest assured those codes are in place for good reasons.

 

 

[Crossy]

24 minutes ago, Cashboy said:

I was under the impression it was all about physically fitting in the conduit.

I say that because I managed to get 9 x 1.5mm cables in 1/2" SCG conduit for the lights last week even round those sharp 90 degree bends under the concrete first floor.

 

10 x  1.5mm² cables would be about 40% fill of a 16mm conduit.

 

It's not JUST about getting it in, but that's often a deciding factor, it's also about cable heating. 

 

EDIT TLC Direct have very good guide to the IEE Regs.

It's based on the 16th Edition but the important stuff hasn't changed. A whole section on conduit and trunking, derating factors, packing density and the like. It's here :-

https://www.tlc-direct.co.uk/Book/1.1.htm

Enjoy.

[Metropolitian]

On 5/9/2020 at 10:22 AM, Crossy said:

Not a lot to catch fire up there ????

 

Where  ? ????

Seems the post has gone fizzing..

 

Perhaps the reason the editing didn't coming trough was that my neighborhood was experiencing an brownout at that time which I didn't noticed, thanks to the UPS, until the under-voltage protection kicked in and my ventilator stopped.

 

After the brownout, 110 volt, 80 volt, 60 volt, the grid went zero for an hour. The UPS couldn't bridge that.

Once the grid came back online I did jump in the log file of the inverter and saw that it has happened more the last week, but I never noticed it unless yesterday.

A threadstarter soon. ????

 

 

On 5/10/2020 at 9:48 AM, Cashboy said:

I managed to get 9 x 1.5mm cables in 1/2" SCG conduit

Try to keep the wiring for the lights separate, especially with stairway switching. Otherwise you would encounter ghosting with led lights.

 

Some example when led lights 'ghosting' is when the feed to the light is live and the switch is on the neutral line, (which of course is wrong, but I have seen it many times here) then the neutral wire coming back from the light is a little bit 'live' when the switch is off and working as an capacitance antenna it will conduct very little currents, causing the led lights glow faintly

It also occurs when the wiring is right (eg. the live wire to the switch and then switch wire to the light and then going to the neutral) and the switching wires are in the same conduit as some heavy current live wires (aircons, ovens, etc..) it CAN make the led lights glow a bit.

 

Crossy already mentioned about the L and N wires together in the small box when it is metal due to the foucault/eddy currents, the same goes up within conduits. Try avoiding sharing neutrals and have the return path for the heavy currents wiring trough the same conduit.

 

Informative youtube video on 'one-way ' AC currents trough separate holes in a metal base.

 

 

[Metropolitian]

On 5/9/2020 at 9:26 PM, Cashboy said:

 

I based all that on the standard government available supply:

 

 

I was under the impression that I would order the 15(45) whatever that is.

I was under the impression from questions on here that it would be a 60 Amp supply even though I don't see any correlation between 15(45) and 60 amp single phase.

The image only shows the pricing of the meter, the deposit and the monthly rent for the meter and distribution as well as the inspection fees and another servicing fees.

Nothing about cable diameter in the image but you can get that information from the PEA/MEA website and of course from their offices.

 

15(45) is what most people have and will be sufficient for most places.

The meter can carry much more amps then its rating even 100amp but will be less accurate.

 

Which are caused by the wheel spinning faster (in case of analog metering) and the magnetism sensing (eddy..) from the disc is getting out of sync and writing down more IMP pulses then the real usage.

With digital meters (smartmeters) it is the electronics that wouldn't sense the exceeding amps and counting maximum plus extra charging you for it.

 

If you have a new installation and the inspection still has to be done then you need a 50 amp main breaker as that is likely what they want to see.

If you need more then after inspection you can upgrade that tot 63amp.