Electrical Tutorials -Safe Electricity Without a Ground

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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby Roger Ramjet » Fri Aug 26, 2011 8:49 am

nanbuilder,
You're going to have all sorts of similar problems with everyone pontificating their preferred way of doing things. I asked the air conditioning people why they wanted to place a breaker on the wall when it was a direct connection to the designated breaker on the Safe-T-Cut board, which also has an RCBO. Their reply was, "Well you can use it as an on/off switch as well" (and I asked "Won't the remote do that"?) and "That's the way we've always done it in a Thai house" and the final one "It was in the price of the air conditioner".
I'm going to stick with the Safe-T-Cut with inbuilt RCBO. If it says the appliance must be earthed, then that will go through the Safe-T-Cut board as well, and the earth spike will go into the ground at the grey water outlet on a designated ground line at either side of the house (we have two sewerage systems and two grey water outlets, one on either side of the house. The grey water outlet will go into the French drain on either side. If anyone gets "fried" then there's a lot of insurance money to be collected... if the "sparky" has done his job properly. And so far all the tradespeople my builder has used and pays have all been superb.
My builder and the "sparky" have gone through the different electrical items we are installing and have prepared a list of the five different wires and the amperage capacity needed for each item. I'll post photos when the "sparky" starts in ernest next week and gives me the complete list. It may help.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby nanbuilder » Sat Aug 27, 2011 7:30 am

Roger Ramjet wrote:nanbuilder,
You're going to have all sorts of similar problems with everyone pontificating their preferred way of doing things. I asked the air conditioning people why they wanted to place a breaker on the wall when it was a direct connection to the designated breaker on the Safe-T-Cut board, which also has an RCBO. Their reply was, "Well you can use it as an on/off switch as well" (and I asked "Won't the remote do that"?) and "That's the way we've always done it in a Thai house" and the final one "It was in the price of the air conditioner".
I'm going to stick with the Safe-T-Cut with inbuilt RCBO. If it says the appliance must be earthed, then that will go through the Safe-T-Cut board as well, and the earth spike will go into the ground at the grey water outlet on a designated ground line at either side of the house (we have two sewerage systems and two grey water outlets, one on either side of the house. The grey water outlet will go into the French drain on either side. If anyone gets "fried" then there's a lot of insurance money to be collected... if the "sparky" has done his job properly. And so far all the tradespeople my builder has used and pays have all been superb.
My builder and the "sparky" have gone through the different electrical items we are installing and have prepared a list of the five different wires and the amperage capacity needed for each item. I'll post photos when the "sparky" starts in ernest next week and gives me the complete list. It may help.


Hi Roger - thanks for the guidance once again. I'm with you on the RCBO and will not succumb to pontification :lol:
Looking forwards to seeing the list and progress photo's when you are able. Planned date for installation of the Safe T Cut into the chalet is mid October so hopefully will follow yours nicely.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby Ians » Sat Aug 27, 2011 1:41 pm

nanbuilder wrote:
nanbuilder wrote:

Quick update. My builders merchant, after seeing the sketch plan for the chalet, tells me an RCBO is a waste of money! Additionally the 4 'breakers' should (in his opinion) be 2x 32amp and 2x15amp. To be clear the electric supply is single phase. I am no sparky, but to me he is over-rating the amperage for the appliances to be connected (listed above), and no RCBO brings us back to the 'no earth' argument and debate. Maybe he (the builders merchant) should stick to roof tiles and cement on the advice front? Yours truly, confused from Nan!

IMG_5992.JPG


Correct, he should stick with tiles and cement, that's provided he has a slightly better grasp on knowledge needed for these products than what he has on electrics. RCB should be your first line of defence after a correctly installed wiring system.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby John » Tue Jan 03, 2012 9:43 am

Roger Ramjet wrote:I asked the air conditioning people why they wanted to place a breaker on the wall when it was a direct connection to the designated breaker on the Safe-T-Cut board, which also has an RCBO. Their reply was, "Well you can use it as an on/off switch as well" (and I asked "Won't the remote do that"?) and "That's the way we've always done it in a Thai house"


Local isolation is mandatory for fixed appliances in the electrical code of many countries. This is because distribution boards mounted far away from the appliance do not meet isolation time standards. Having local isolation is good for maintenance and also allows you to take away any standby power used by the appliance when not in use. A/C’s in rooms that are rarely used will be constantly drawing power in standby mode if not fitted with an isolator.
In this rare case the Thai installer is offering an advantageous and sensible addition.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby otis-a » Tue Jan 03, 2012 12:35 pm

umm
does john's point imply that wet area rcbo (gfi ground fault interrupter) sockets are a preferred option with local socket switch?
Last time i looked at the usa codes, gfi sockets were mandatory in wet areas. Don't recall a requirement for switched sockets.
Industrial codes call for 'lock-out' breakers. The mandatory lock(s) are placed by service personnel to ensure power not tripped on by second parties while maintiance work is on going. Mandatory means requirement for opening and closing a permit to work.
One story relates to guys doing work inside some finfan coolers without lockout. The 'dead' fan was tripped on with 2 workers inside. Unfortunately, the workers were summarily macerated by rotating fanblades.
I never hear of lock-out breakers in home use.
The idea: ''line of sight'' is good alternative to ensure positive power off, if lockouts are not used.
A good many old commercial installs are without 'lock out' systems. A practice is: 'tape over' a breaker during work. Some older breaker boxes were supplied with a key lock. Practically speaking the 'key(s)' are generally lost, rendering the lock box useless. A clue for 'lost key' is the bb pannel door locked closed but door will be open always. Other locked pannels locked open with no key to be found.
where to park dog when in town? A barking lot... :-)))
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby John » Tue Jan 03, 2012 2:13 pm

otis-a wrote:umm
does john's point imply that wet area rcbo (gfi ground fault interrupter) sockets are a preferred option with local socket switch?



Picture shows arrow pointing to isolation switch on the wall for AC above window. In this case 3 AC units are supplied from a common branch circuit so the isolation switch (MCB) also provides over current protection.
This is what Roger Ramjet’s AC installer offered to fit.


Image
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby olavhome » Sun Aug 05, 2012 5:19 pm

But, looking at where the switch is placed is typical of LOS. Why not put it beside window , so it can be hidden by curtains :)
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby geordie » Sun Aug 05, 2012 7:07 pm

olavhome wrote:But, looking at where the switch is placed is typical of LOS. Why not put it beside window , so it can be hidden by curtains :)

That would demonstrate comonsense a bit thin on the ground here I
I agree with the pricipal of having a local isolation for both safety as john suggested also why leave it in standby for months at a time as otis pointed out
my comments may be wrong but never deliberately
If it aint broke, dont fix it
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby cooked » Sat Sep 07, 2013 6:42 am

I got a mild shock off my computer while plugging in my iPhone and dropped the f***ing thing yesterday, irreparable. No earthing anywhere in the house, but I do have an old Safe-T-Cut which works when I press the 'test' button but has never swung into action up to now, I set it to 5. (mA?).
So first question, as there is no earthing anywhere, can I just run a thick, uninsulated copper cable from the back of my computer through the wall to an earthing rod? What happens if there is a short circuit elsewhere, won't the zap go through the path of least resistance, meaning my computer?
Second, is the Safetcut working? I got a real shock while plugging something in last month, the cable comes from the Safetcut. I really want to get the house safe but there don't seem to be any competent electricians around, a socket installed by an electrician recently stopped working after a month.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby Roger Ramjet » Sat Sep 07, 2013 8:53 am

cooked,
cooked wrote:No earthing anywhere in the house, but I do have an old Safe-T-Cut which works when I press the 'test' button but has never swung into action up to now, I set it to 5. (mA?).

The Safe-T-Cut board should have tripped, but as you have no earth anywhere in the house the overload current just escapes through you, as you act as the earth. Running an earth wire from the computer will just cause the board to trip each time (overload). I would have the computer looked at, and I would have the board wired for earth, but I think the problem lies within the computer.
cooked wrote:installed by an electrician recently stopped working after a month.

That would be the first place I would look at with a test meter.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby cooked » Sat Sep 07, 2013 9:53 am

Thanks for your prompt answer! The shock I got from the computer feels like static electricity - but I will take it in if you think I should do that.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby Ians » Sat Sep 07, 2013 11:01 am

Nothing wrong with the computer, they are inherently "leaky" and unless earthed you will get continual reminders. I'm not qualified to expand on the reaons for this but searching on the internet should give you the answers. Running a dedicated earth should fix your problem.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby cooked » Sat Sep 07, 2013 11:16 am

OK, will do that tomorrow and let you know!
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby John » Sat Sep 07, 2013 4:20 pm

Ians wrote:Nothing wrong with the computer, they are inherently "leaky" and unless earthed you will get continual reminders. I'm not qualified to expand on the reaons for this but searching on the internet should give you the answers. Running a dedicated earth should fix your problem.


Yes that's correct but if a component in the power supply fails it can be a lot more serious if no ground is present.

COMPUTER POWER SUPPLY

The above link shows typical switch mode power supply in computer. In the top left corner there are filter capacitors looking for ground. Its components like these that give you a zap when touching a computer case without ground.

In most cases the leakage current is well below a ELCB minimum.
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Re: Electrical Tutorials -Safe Electricity Without a Ground

Postby cooked » Sat Sep 07, 2013 5:17 pm

ummm... judging by the naivety of my question, did you think that this would be of any help? Qualified electricians always do this. Anybody that understands the diagram won't need it.
Maybe a slightly rude response, sorry.
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