Workshop power...sub-board required or not?

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Workshop power...sub-board required or not?

Postby Thaifelix » Mon Jan 12, 2015 2:27 pm

Hi everyone,
I am currently drawing up plans for a small workshop to be built appx 25 mts from my house. The house has a Schneider/Square D 10 slot distribution box with RCBO and a slot reserved for the workshop. I dont envisage using anything more than a few hobby tools such as small sanders, circular saw, drill, small air compressor and maybe a small arc welder/inverter. I may also in the future need to put in a bore pump as town water is becoming increasing unreliable with the current drought.

My questions are: Should I put in a separate distribution box in the workshop? Should it run through the box in the house or direct from pole and what size circuit breaker/s should I use? Is it best to put in a separate earth rod for the workshop or connect to the existing house one?
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Re: Workshop power...sub-board required or not?

Postby Thaifelix » Fri Jan 16, 2015 11:15 am

Gee its just like that old movie "On the Beach".....nobody is out there??!! :o
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Re: Workshop power...sub-board required or not?

Postby fredlk » Fri Jan 16, 2015 12:03 pm

Thaifelix wrote:Gee its just like that old movie "On the Beach".....nobody is out there??!! :o

I'm out here, but know nothing about electrics. I could say yes but it might be wrong.
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Re: Workshop power...sub-board required or not?

Postby Roger Ramjet » Fri Jan 16, 2015 8:29 pm

Thaifelix wrote:Gee its just like that old movie "On the Beach".....nobody is out there??!!

I have a workshop/garage that is on a seperate circuit and has a seperate circuit board. There are two reasons for that, the first is I don't want to walk all the way into the house if I trip something, the second is because of the floods that hit us three years ago. I want to be able to isolate the workshop/garage, gate opener, security lights etc if need be. I certainly don't want a "live" flood water around the garage/workshop to electrocute help before it arrives.
It all depends on what you intend running in the workshop, but going by what you posted I would be doing the same again.....separate board, separate circuit. I have two circuit boards in the house, one for each floor. It's a personal choice for me, my workshop in Australia used to trip the switches sometimes so I had a separate board installed. It's easier to do when you're building the workshop than it is after it's built.
Nobody was out there as you say.....I have a bad internet connection today.....perhaps you could talk to TOT for me and lodge a complaint? :D :D
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Re: Workshop power...sub-board required or not?

Postby Thaifelix » Fri Jan 16, 2015 11:23 pm

Roger Ramjet wrote:
Thaifelix wrote:Gee its just like that old movie "On the Beach".....nobody is out there??!!

I have a workshop/garage that is on a seperate circuit and has a seperate circuit board. There are two reasons for that, the first is I don't want to walk all the way into the house if I trip something, the second is because of the floods that hit us three years ago. I want to be able to isolate the workshop/garage, gate opener, security lights etc if need be. I certainly don't want a "live" flood water around the garage/workshop to electrocute help before it arrives.
It all depends on what you intend running in the workshop, but going by what you posted I would be doing the same again.....separate board, separate circuit. I have two circuit boards in the house, one for each floor. It's a personal choice for me, my workshop in Australia used to trip the switches sometimes so I had a separate board installed. It's easier to do when you're building the workshop than it is after it's built.
Nobody was out there as you say.....I have a bad internet connection today.....perhaps you could talk to TOT for me and lodge a complaint? :D :D


Thanks for the response Roger, some good logic there. Not sure what you mean by a separate circuit for the garage........do you mean another feed from the power pole/meter or a separate line from the house consumer unit to the workshop? I was thinking of setting up the workshop power as an extension to the house power ie a 35amp circuit breaker in the house consumer unit exclusively for the workshop feeding a separate consumer unit in the workshop with circuit breakers for lights, power points etc. What I am not sure about is whether or not to include a main switch with RCBO as I have in the house.....will two in a line affect its operation? I have also been doing a lot of reading about earth rods/earthing and there seems to be a lot of arguments for and against a separate earth rod for a workshop. However my feelings/conclusions are that if the w/shop power is an extension of the house power then the earthing should be the same so an earth wire should run from the house earthing or CU to the workshop. Any thoughts?

As far as TOT goes I doubt I could be of any help as I have had no luck with them myself. Been in this small moo barn out in the sticks now for over a year and have only had internet at home here for last month and an air-card at that. No land lines at all. Previously had to drive 10kms out of town just to check my email, forget about sharing my house build haha. You are going to have to enlist somebody else I'm sorry :roll:
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Re: Workshop power...sub-board required or not?

Postby Thaifelix » Fri Jan 16, 2015 11:42 pm

fredlk wrote:
Thaifelix wrote:Gee its just like that old movie "On the Beach".....nobody is out there??!! :o

I'm out here, but know nothing about electrics. I could say yes but it might be wrong.


Hey thanks anyhow for the response fredlk. I gotta tell you that your build story (as well as the fact I come from Oz so have experience) sold me on the kliplok off white roofing and I am a proud owner now. So pleased I have just taken delivery of my second order which will be used for an extended roof/verandah going all around my house....cant wait. However dealing with the Bluescope Khon Kaen branch is like having teeth pulled. They have only one lady who understands enough English to get her into trouble but by email or even with my wife translating it was difficult to communicate...took three weeks just to order!! I must say though she seemed like she was overworked but trying hard.
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Re: Workshop power...sub-board required or not?

Postby fredlk » Sat Jan 17, 2015 6:16 am

Thaifelix wrote: I gotta tell you that your build story (as well as the fact I come from Oz so have experience) sold me on the kliplok off white roofing and I am a proud owner now. So pleased I have just taken delivery of my second order which will be used for an extended roof/verandah going all around my house....cant wait. However dealing with the Bluescope Khon Kaen branch is like having teeth pulled. They have only one lady who understands enough English to get her into trouble but by email or even with my wife translating it was difficult to communicate...took three weeks just to order!! I must say though she seemed like she was overworked but trying hard.

I am also very happy with the choice I made. It seems there are two camps, the Intertech-lot who are very happy with their roofing company and others who have some issues. When I continue building I'll be contacting Intertech.
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Re: Workshop power...sub-board required or not?

Postby Roger Ramjet » Sat Jan 17, 2015 8:22 am

Thaifelix wrote:Not sure what you mean by a separate circuit for the garage..

Here's how it works in my house. The main feed comes from the power pole to a R/H corner column then through under the roof to the main breaker switch (100 amp). There's a reason for using the Mitsubishi 100 amp breaker switch and it's because we have a 45/100 amp meter. What's the point in having a 45/100 amp meter that will trip the main breaker everytime there is a surge over your 35 amp breaker? As far as I know all the electrical mobs in Thailand (4 fiefdoms) have 15/30, 15/45 and 45/100 meters, the 15/30 are for poor Thais only, the other two are for cheap and rich "farang" respectively. :D
From the breaker switch the main feeds into the first Safe-T-Cut board, then comes out again on two other sseperate lines, each with their own breaker. One goes upstairs to another Safe-T-Cut board, the other to the workshop on another Safe-T-Cut. All these boards have built in RCBOs for testing your circuits ever three months.
When you look logically at what you want to run in a house, whether it is the simple life, or the involved life, there are a lot of electrical wires. If it's complex like my house where I have many many power outlets each with their own on/off switch at each power point (there's photos on my building story) then all those wires just don't fit in one board. The Thais get around this by ponying them together before they get there, which means you can never tell what is happening on one circuit, let alone two. Mine are all marked (in bloody Thai I might add) so at least my wife or daughter can tell me what might be wrong.
At my townhouse I got sick and tired of watching "electricians" from air conditioning companies and water heating companies wire straight into the mains power slot, then tell my wife that was how it's done in Thailand.....meanwhile the breaker slots designed for them sat empty. I also got sick and tired of turning back on the breaker switch for the hot water heater because they had wired it into the wrong circuit on the new board I had installed.
As I said it's a personal choice on whether to have separate circuits or not. I know in Australia I got sick of walking from the workshop to the house to throuw the breaker switch all the time, so I had a separate board installed and also put in three phase power to the workshop. I had three daughters and it seemed all their potential suiters were either mechanics, petrol heads, or some other related trade and all decided that working in my workshop on their cars was a great way to get to know "the daughter" they were after. :D
The "what if", the flood has already happened. I like to vector in what ifs when putting things together, it saves time, money and effort in the future.
I hope that helps.
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Re: Workshop power...sub-board required or not?

Postby Thaifelix » Sat Jan 17, 2015 6:51 pm

Roger Ramjet wrote:
Thaifelix wrote:Not sure what you mean by a separate circuit for the garage..

Here's how it works in my house. The main feed comes from the power pole to a R/H corner column then through under the roof to the main breaker switch (100 amp). There's a reason for using the Mitsubishi 100 amp breaker switch and it's because we have a 45/100 amp meter. What's the point in having a 45/100 amp meter that will trip the main breaker everytime there is a surge over your 35 amp breaker? As far as I know all the electrical mobs in Thailand (4 fiefdoms) have 15/30, 15/45 and 45/100 meters, the 15/30 are for poor Thais only, the other two are for cheap and rich "farang" respectively. :D
From the breaker switch the main feeds into the first Safe-T-Cut board, then comes out again on two other sseperate lines, each with their own breaker. One goes upstairs to another Safe-T-Cut board, the other to the workshop on another Safe-T-Cut. All these boards have built in RCBOs for testing your circuits ever three months.
When you look logically at what you want to run in a house, whether it is the simple life, or the involved life, there are a lot of electrical wires. If it's complex like my house where I have many many power outlets each with their own on/off switch at each power point (there's photos on my building story) then all those wires just don't fit in one board. The Thais get around this by ponying them together before they get there, which means you can never tell what is happening on one circuit, let alone two. Mine are all marked (in bloody Thai I might add) so at least my wife or daughter can tell me what might be wrong.
At my townhouse I got sick and tired of watching "electricians" from air conditioning companies and water heating companies wire straight into the mains power slot, then tell my wife that was how it's done in Thailand.....meanwhile the breaker slots designed for them sat empty. I also got sick and tired of turning back on the breaker switch for the hot water heater because they had wired it into the wrong circuit on the new board I had installed.
As I said it's a personal choice on whether to have separate circuits or not. I know in Australia I got sick of walking from the workshop to the house to throuw the breaker switch all the time, so I had a separate board installed and also put in three phase power to the workshop. I had three daughters and it seemed all their potential suiters were either mechanics, petrol heads, or some other related trade and all decided that working in my workshop on their cars was a great way to get to know "the daughter" they were after. :D
The "what if", the flood has already happened. I like to vector in what ifs when putting things together, it saves time, money and effort in the future.
I hope that helps.


Thank you very much Roger for your very informative response. I agree with your philosophy to the point you remind me of a Rotary Club sign I used to hang proudly in my workshop back in Australia. It read: "Do a job once, do it right. Build a better Australia." My biggest hate in life is redoing a job...even though it sometimes leads to some confrontations with " her in-doors" as the Poms would say. For example my house, along with my plans for future workshop, are for a build sitting 30 cms above normal ground level, "just in case", even though we are in an area where there is very little chance of flooding.

Ok very good so far but what is your opinion re the earthing mentioned above?

My sympathies re the 3 daughters. I totally understand but am somewhat lucky having only one. Although I love her very much I often think it would be easier rearing those who go out and "hunt" rather than those who are "hunted" :wink:
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Re: Workshop power...sub-board required or not?

Postby thailazer » Sat Jan 17, 2015 8:52 pm

Thaifelix.... Here is what I would do in your case, which might not be the norm but would be safe:

-Put a 32 amp RCD-type (10 mA trip) breaker in your distribution box in the house. (The RCD breaker will protect overloads and for shock hazard. )

-Run 6 mm -squared 2 conductor Direct Burial cable out to your shop. Bury it deep and put a tracer plastic ribbon above it so diggers in the future will know something is there.

-Install a ground rod at your shop and use earthed outlets to this ground rod. (Normal practice would have you run an earth line all the way back to the house, but for me, the reliability of a closer connection makes sense. ( I have had a lot of lightning strike experience in my past jobs.)





That would support most of your loads except for old style welders. Buy an inverter type and that would likely work fine with the 32 amp breaker.
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Re: Workshop power...sub-board required or not?

Postby Roger Ramjet » Sat Jan 17, 2015 9:30 pm

Thaifelix wrote:Ok very good so far but what is your opinion re the earthing mentioned above?

I have three separate earths, one for each board. There are three rods to each, all connected by the proper copper shackles and all in areas where there is a French drain, so the ground never goes dry. Of course various "builders" and other oddbods have managed to bugger two of them because they had no idea what they were. The copper rods are cheap and so are the shackles, so I just went to town with the electrician who loved doing it properly.
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Re: Workshop power...sub-board required or not?

Postby Sometimewoodworker » Sat Jan 17, 2015 10:48 pm

Roger Ramjet wrote:
Thaifelix wrote:Ok very good so far but what is your opinion re the earthing mentioned above?

I have three separate earths, one for each board. There are three rods to each, all connected by the proper copper shackles and all in areas where there is a French drain, so the ground never goes dry. Of course various "builders" and other oddbods have managed to bugger two of them because they had no idea what they were. The copper rods are cheap and so are the shackles, so I just went to town with the electrician who loved doing it properly.


Good thing too. 3 separate earths, one for each board is perfect for ground loop problems.

One earth for 1 house with three bonded earthing rods is what you want. you should also bond the earth and neutral at the main board.
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Re: Workshop power...sub-board required or not?

Postby Thaifelix » Sun Jan 18, 2015 10:29 pm

Sometimewoodworker wrote:
Roger Ramjet wrote:
Thaifelix wrote:Ok very good so far but what is your opinion re the earthing mentioned above?

I have three separate earths, one for each board. There are three rods to each, all connected by the proper copper shackles and all in areas where there is a French drain, so the ground never goes dry. Of course various "builders" and other oddbods have managed to bugger two of them because they had no idea what they were. The copper rods are cheap and so are the shackles, so I just went to town with the electrician who loved doing it properly.


Good thing too. 3 separate earths, one for each board is perfect for ground loop problems.

One earth for 1 house with three bonded earthing rods is what you want. you should also bond the earth and neutral at the main board.



Thanks. When you say "bonded" do you mean the three rods are interconnected? From what I understand the earth and neutral are already linked together in the main board (MENS system?)
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Re: Workshop power...sub-board required or not?

Postby Roger Ramjet » Mon Jan 19, 2015 5:18 am

Sometimewoodworker wrote:Good thing too. 3 separate earths, one for each board is perfect for ground loop problems.

One earth for 1 house with three bonded earthing rods is what you want. you should also bond the earth and neutral at the main board.

Sometimewoodworker,
Please explain why an earth rod ( in my case three lots of three) causes ground loop problems. I have a house, I have no high end electrical components in the house. I do not have hospital equipment that can cause noise. So please explain in great detail why my house earth should cause noise and why.
Why do people need bonded earthing rods? Why three and why one only for each house. Also please enlighten about "bonding" the earth and neutral at the main board and why, and when you have three boards why you shouldn't do the same at each board. In your own words please.
Perhaps you'd like to explain bonding. No need to post all those technical sites/guesses from Panarama, as I said I don't have a hospital, I don't have high end technical equipment either.
I'd love to learn about lightening strikes and how to stop them too. All data on that I shall pass to the university so they came pass it to the power companies so they no longer lose transformers. Make it technical in your own words too.
Scientists have never been able to fully understand lightening strikes, other than why they occur, and go to the least line of resistance by sending down "feelers" so Coolthaihouse will become famous for it's knowledge soon, which I shall duly pass on to Wiki and those dumb Professors at universities.
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Re: Workshop power...sub-board required or not?

Postby Sometimewoodworker » Mon Jan 19, 2015 7:19 am

Thaifelix wrote:
Sometimewoodworker wrote:
Good thing too. 3 separate earths, one for each board is perfect for ground loop problems.

One earth for 1 house with three bonded earthing rods is what you want. you should also bond the earth and neutral at the main board.



Thanks. When you say "bonded" do you mean the three rods are interconnected? From what I understand the earth and neutral are already linked together in the main board (MENS system?)

The common term for connecting electrical earth to neutral in the board is bonding again the comon term for connecting earth rods together to each other is bonding.
The ideal connection for the earth to the electrical system is, as you say, in the main board. Many Thai systems do not have any earthing or if the do only some sockets are earthed.
Most thay houses have only 2 wire connections to all outlets.

The reason for saying 1 earth connection for 1 house is that it is very unusual for people to have 2 or more completely independent supplies

If you have a single supply with sub boards you should have a single earth connection. The bonding of earth rods to that connection is to ensure that the earth is functioning. The reason to have a single earth for a single supply is to avoid earth loops, and mainly why you don't want earth loops is the interference they cause in sound and computer systems. Earth loops can also cause interference other things like WiFi or ethernet

Ground loops are a mystery to many people. Even college-trained electronic engineers may not know what ground loops actually are. Engineers have either concentrated on power distribution (for the electric company) or on equipment that happens to plug in to the power distribution system. Not much thought has been given to power distribution and equipment as a single entity where ground loops arise.

Ground loops are the most common cause of AC line frequency hum in sound systems. Ground loops can be geenrally identified by a low hum (60Hz in the US, 50Hz in Europe) through the sound system. A ground loop in the power or video signal occurs when some components in the same system are receiving its power from a different ground than other components, or the ground potential between two pieces of equipment is not identical.

Read more about audio at: http://www.epanorama.net/documents/groundloop/

There is also a system of connecting to the rebar inside the concrete and so using the entire structure of the house as an earth but I don't know enough to know what problems that has.

PS to RR the sensible questions you asked are answered here. Do please inform us about lightning strike and why we should be concerned in relation to grounding a domestic electrical system?

See also http://en.m.wikipedia.org/wiki/Ground_loop_(electricity)#

For CEE (Concrete Encased Electrode) grounding see http://en.m.wikipedia.org/wiki/Ufer_ground
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