N joined to Ground or Earth

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John61

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Kanchanaburi, Thailand
Hi All

I am John from England BUT living in Thailand for the last 12 years. We have a solar business here.
In Thailand the electric is 220v as back home. Back home I had a company that was NIC approved for over 10 years although not my self BUT the engineers were, so I do understand a little bit about electric.

I have a problem at the moment, The Thai have a habit off joining the N line to the E/G Earth/ground, We have just fitted a 5kw system to a friends home and the Grid Tie is showing a Grid Fault, Isolation Error, We have traced it back to the fuse box and found the N line connected to the E/G line. After we separated this we still have the problem. Looking out side we found a electric pole next to the home and found that they have joined the N to the ground. In my understanding this should never be done like this, as N then becomes NG or NE,

What is your thoughts as I am confused to why they would do this.

Also I checked the fuse box with a volt meter, checking L and N getting 236v Checking L and G still getting 235 volts. Checking L and the fuse box were the screws hold the cover on, still getting 235v. We went next door and got the same readings. Now please correct me if I am wrong in thinking this should not happen.

Mind you we do have a saying here in Thailand TiT,,, This is Thailand

Thank you for your time.
John
 
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Sounds completely correct to me?
the neutral of the transformer on pole will go to earth ground as well as the neutral in your service panel will also.
 
John, you haven't provided much in the way of details of the equipment you're installing, but from what you wrote it sounds like some aspects of this are over your head. You should not be disconnecting grounds or neutrals in a panel unless you are intimately familiar with the local requirements and the theory behind them, which it sounds like you are not. My recommendation would be to find and retain the services of a qualified electrician or electrical engineer locally who can provide you the answers you need.
 
I would bet that if you found neutral and ground connected together in all those places then that's how it is supposed to be done in Thailand. From your description it sounds like possibly the N-G bond was done in two places in the home where it should only have been done at one. But this should make no difference as to whether your inverter operates.

It's the same here in the States; we call the neutral a 'grounded conductor'. (The differences are that here in the States we usually have two or three hot legs, the line-to-neutral voltage on residential is 120V, and we connect inverters line-to-line.)

What you need to look into is whether your inverter is approved to be connected Line-to-Neutral, where Neutral is grounded. It could be that you simply need to change the settings on the inverter, most likely with tech support help from the manufacturer. (They may need to give you a code, etc.) Or it could be that you cannot use this inverter on this type of grid connection.

I suppose it could also be that there is some other type of undetected ground-fault on the system. Seems pretty unlikely though.

For more on different earthing systems, see: http://en.wikipedia.org/wiki/Earthing_system I have no idea what Thai regulations are.

EDIT: I also agree with Petros. You should find out what the local system is supposed to be and have someone local confirm that it's installed correctly. If you need to contact the inverter manufacturer you need to be giving them clear and correct info about the grid.
 
mopowr steve said:
Sounds completely correct to me?
the neutral of the transformer on pole will go to earth ground as well as the neutral in your service panel will also.
Click to expand...

I understand at the transformer the neutral will go to ground BUT the transformer is about a mile away. The pole is next to the home. I do not understand why you would join the neutral line and the ground line as one in the fuse box.
 
PetrosA said:
John, you haven't provided much in the way of details of the equipment you're installing, but from what you wrote it sounds like some aspects of this are over your head. You should not be disconnecting grounds or neutrals in a panel unless you are intimately familiar with the local requirements and the theory behind them, which it sounds like you are not. My recommendation would be to find and retain the services of a qualified electrician or electrical engineer locally who can provide you the answers you need.
Click to expand...


One off the problems here is getting someone that is qualified. I have come across this problem before as some parts off this area they join the neutral to ground and in other areas they do not. After we separated the neutral and ground on the other home the grid tie worked OK as it was only joined in the fuse box and not on the pole. I have spoke to 4 electricians 3 say noway to joining the N to the G and 1 says yes he does it all the time. My understanding is these 2 lines are separate in the fuse box for a reason,
 
jaggedben said:
I would bet that if you found neutral and ground connected together in all those places then that's how it is supposed to be done in Thailand. From your description it sounds like possibly the N-G bond was done in two places in the home where it should only have been done at one. But this should make no difference as to whether your inverter operates.

It's the same here in the States; we call the neutral a 'grounded conductor'. (The differences are that here in the States we usually have two or three hot legs, the line-to-neutral voltage on residential is 120V, and we connect inverters line-to-line.)

What you need to look into is whether your inverter is approved to be connected Line-to-Neutral, where Neutral is grounded. It could be that you simply need to change the settings on the inverter, most likely with tech support help from the manufacturer. (They may need to give you a code, etc.) Or it could be that you cannot use this inverter on this type of grid connection.

I suppose it could also be that there is some other type of undetected ground-fault on the system. Seems pretty unlikely though.

For more on different earthing systems, see: http://en.wikipedia.org/wiki/Earthing_system I have no idea what Thai regulations are.

EDIT: I also agree with Petros. You should find out what the local system is supposed to be and have someone local confirm that it's installed correctly. If you need to contact the inverter manufacturer you need to be giving them clear and correct info about the grid.
Click to expand...

Not all is the same here, only small part of this area has N joined to G and others say noway. After speaking to one that says yes he does it all the time, I asked him why and his answer was it saves about 5% on the electric bill.

I have emailed the grid tie company and waiting for a reply.
 
John61 said:
I understand at the transformer the neutral will go to ground BUT the transformer is about a mile away. The pole is next to the home. I do not understand why you would join the neutral line and the ground line as one in the fuse box.
Click to expand...

Grounding a conductor is done to provide a low-impedance fault path to open fuses or circuit breakers if there is an fault from the other conductor(s) to ground or to grounded parts. So it's a basic safety method that I believe a majority of countries use. The bond is typically supposed to be done where the electrical service disconnect is, and not anywhere else in a home.

If you don't have a grounded conductor then there's probably supposed to be an RCD at the home's main disconnect. France and Japan and a fe other countries do this, I believe. Again I have no idea about Thailand.

Grounding a conductor also helps to stabilize voltages.
 
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