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Generator change over switch

Rc3

Hi all I have a job coming up soon, which includes the install of a generator change over switch, just in relation to the main neutral from the ESB side is it a case of redirecting this though change over switch, and my main neutral from generator does this need to be earthed at generator?

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Reisers

I think my point was well made

If a contractor provides a plug for the connection of a standby generator he should switch the live poles.

Its an invitation to connect anything that starts up to the grid otherwise.

Steve

Reisers wrote: »

I think my point was well made

If a contractor provides a plug for the connection of a standby generator he should switch the live poles.

Its an invitation to connect anything that starts up to the grid otherwise.

live poles

There is only one live pole - in a 1~ domestic installation.

The neutral or PE is not a "live pole"

Reisers

Steve wrote: »

There is only one live pole - in a 1~ domestic installation.

The neutral or PE is not a "live pole"

It sure is

Live means forming part of a circuit here

Reisers

A lot of posters struggling with definitions here

Live pole or conductor - pole or conductor forming part of a circuit

Supply pole- live pole of the electricity supply( not a PE)

Switching earths not allowed as per rules

2011

Reisers wrote: »

A lot of posters struggling with definitions here

Maybe it is not everyone else

When you use new electrical terms like "draining a generator" or invent a safeguard against the use of 110-0-110 generators that do not seem to exist it will generate questions. These questions should not be interrupted as "struggling".

When challenged on your position you ignore questions that are put to you which suggests that you don’t have the answers.

Switching earths not allowed as per rules

This has been done to death, do not derail the thread any further with this.

This is a discussion forum so if you express a view others are entitled to ask questions on it especially if it is a bit more novel. Please keep it friendly.

It’s ironic that your most valid point (we have no control over what is plugged to a generator socket) actually makes the argument for not switching the neutral.

Reisers

Draining a generator isn't an electrical term

I mean there's a load on the generator

2011

Reisers wrote: »

Draining a generator isn't an electrical term

I mean there's a load on the generator

Incorrect, if it had the short you suggested it would have tripped therefore no load could be applied.
If it had a neutral to earth “fault” as you suggested this would not apply any extra load to a generator.

Reisers

Did I say short?

Stoner

Reisers wrote: »

A lot of posters struggling with definitions here

Agreed, and you are in the mix yourself in fairness Reisers.

I'll ask again for the second and last time that we read the charter, note the points on super sparks and cut out the oneupmanship please.

karolaug

I have changeover switch installed in my house and both live poles are switched. There is simple reason for it.

Obviously the switching has to be done after the meter but in TN-C-S system the neutral is bounded to earth before the meter on ESB side. In shared neutral scenario if generator has also neutral bounded to earth there will be two bounding points, which is wrong. If the generator had floating neutral then any fault current would go through the meter even if the house is powered by generator which shouldn't be the case.

In my case I use small Honda generator that has floating neutral so in order to ensure that installation still has functioning PE I have N and PE bridged in generator plug. That way fault current goes through PE and to N in the generator. It also neutralizes the generator as PE is obviously connected to the ground pole and to the ESB neutral that is grounded in multiple places in the network.

Generator has PE and N bounded and PE is connected to ESB N and ground pole. Generator N is neutralized and there is path from PE in the house to N on the generator so RCD trips in case of any fault. Without the PE to N connection on the generator the PE in the house wouldn't work at all (no connection to the N in the generator) and by touching two faulty devices where one has L to PE fault and other N to PE someone would be hurt.

If the neutral was shared the PE path would go from PE bar to shared N before the meter, then trough the meter (N conductor) to the generator, which would be bad. Alternatively in case of PE-N bound in generator there would be two points where PE is bounded to N which is also wrong.

Bruthal

karolaug wrote: »

If the generator had floating neutral then any fault current would go through the meter even if the house is powered by generator which shouldn't be the case.

Just as a matter of interest, the N in and out of the meter is only a solid metal connector, for a voltage reference for true watt measurement. The phase line goes through the meter current measuring setup.

2011

karolaug wrote: »

In shared neutral scenario if generator has also neutral bounded to earth there will be two bounding points, which is wrong.

Agreed, two neutralizing points would be wrong. I am saying there should be just one, at the ESB cut out. This remains in circuit if the neutral remains unswitched.

If the generator had floating neutral then any fault current would go through the meter even if the house is powered by generator which shouldn't be the case.

That is the whole point, the generator could not have a floating neutral if the neutral bar is unswitched as it would be bonded to earth at the ESB cut out. This means that even if someone plugs in a generator, generator lead and generator plug that is not neutraized at any point it will be far safer because the installation itself is robustly neutralized as part of the fixed wiring. This avoids the danger of a floating neutral.

In my case I use small Honda generator that has floating neutral so in order to ensure that installation still has functioning PE I have N and PE bridged in generator plug.

Then you have just connected the neutral of the generator to the ESB neutral, so what is the point in switching the neutral?
Also this deviates from standard practice.

That way fault current goes through PE and to N in the generator.

But the generator PE is connected to the MET which is connected to the the ESB cut out which is connected to the ESB neutral. So even though you switch the ESB neutral off at your changeover switch you have essentially connected the generator neutral to the ESB neutral. What is the point in switching off the ESB neutral if you are going to short out the very same switch?

Bruthal

2011 wrote: »

But the generator PE is connected to the MET which is connected to the the ESB cut out which is connected to the ESB neutral. So even though you switch the ESB neutral off at your changeover switch you have essentially connected the generator neutral to the ESB neutral. What is the point in switching off the ESB neutral if you are going to short out the very same switch?

This disconnecting the ESB N thing came up before. I think I remember the ETCI council member or similar giving reasons to you why it should be disconnected.

I remember being a bit sceptical of reasons given, although I cant find the thread.

Imo a lot of things mentioned or put forward in electrical circles, are based more on convention and traditional teachings,rather than real life tests, or experiences.

2011

Bruthal wrote: »

This disconnecting the ESB N thing came up before. I think I remember the ETCI council member or similar giving reasons to you why it should be disconnected.

I remember being a bit sceptical of reasons given, although I cant find the thread.

Imo a lot of things mentioned or put forward in electrical circles, are based more on convention and traditional teachings,rather than real life tests, or experiences.

But do you accept that in the example just given the neutrals would be electrically connected to each other regardless of the status of the switch?

Bruthal

2011 wrote: »

But do you accept that in the example just given the neutrals would be electrically connected to each other regardless of the status of the switch?

Yes. I was not disagreeing with keeping the ESB neutral connected.

I was just saying it came up before, and the ETCI fella was giving reasons it should be disconnected. Which I thought were theoretical and unlikely.

My other point about teachings and conventions was about the ideas such as the one put forward by the ETCI fella.

I think he had said that there was a risk of neutral current being exported to the network.

As far as I remember anyway.

karolaug

2011 wrote: »

Agreed, two neutralizing points would be wrong. I am saying there should be just one, at the ESB cut out. This remains in circuit if the neutral remains unswitched.

Then you have just connected the neutral of the generator to the ESB neutral, so what is the point in switching the neutral?
Also this deviates from standard practice.

Switching neutral makes sure that there is only one neutralizing point even if the generator is neutralized internally.

Leaving the neutral connected and making sure that generator has floating neutral will use the path through meter to neutralize the generator. As technically it will work I don't believe it's the best practice.

If the ESB removes everything before the meter my setup will still work as ground rod is still in place and if you leave the neutral shared and rely on neutralization point provided by ESB you will lose that.

Depending on the house you can have neutralization point outside the house and it is technically part of the circuit while generator is used. In that case you would have to disconnect the generator whenever there is any work done like meter replacement. The whole point of changeover switch should be to provide safe electricity supply from generator without using part of the circuit that is not owned by customer.

If ESB wants to change the meter in my house they can do it after they remove PE to N connection which is not mandatory for my generator to work and be safe. In your house as you are using the meter as part of the circuit you have to wait in the dark until they finish.

2011

karolaug wrote: »

Switching neutral makes sure that there is only one neutralizing point even if the generator is neutralized internally.

I accept that, but I would far rather run the risk of having two neutralizing points than having none.

Besides you say you are switching the neutral, but electrically you are not. All you are doing is switching a parallel path that connects both neutrals. A simply test meter would prove that both remain electrically connected to each other regardless of the position of the switch. Do you agree or not?

Think about it: If you have 2 neutraizing points what is the risk? All that you have is parallel paths (not ideal I accept, but safe). If you have none you would have a floating neutral which is potentially very dangerous.

Leaving the neutral connected and making sure that generator has floating neutral will use the path through meter to neutralize the generator. As technically it will work I don't believe it's the best practice.

Why?
I would argue that this is standard practice.

If the ESB removes everything before the meter my setup will still work as ground rod is still in place and if you leave the neutral shared and rely on neutralization point provided by ESB you will lose that.

First of all I will still have my earth rod in place as this is not on the ESB side.

Secondly you are ignoring the fact that that your approach does not isolate your generator from the ESB neutral.

Depending on the house you can have neutralization point outside the house and it is technically part of the circuit while generator is used.

Agreed.

In that case you would have to disconnect the generator whenever there is any work done like meter replacement.

Again you are stating this as though you would be isolated from the ESB neutral which is simply not the case. Remember that no current will flow through the neutralising point unless there is a fault condition in which case the current would be minimal (as it provides a higher resistance parallel path). Even if there is a fault condition what is the risk you see?

The whole point of changeover switch should be to provide safe electricity supply from generator without using part of the circuit that is not owned by customer.

Agreed, please identify the risk you see and tell me how your linked out neutral switch mitigates this risk.

If ESB wants to change the meter in my house they can do it after they remove PE to N connection which is not mandatory for my generator to work and be safe. In your house as you are using the meter as part of the circuit you have to wait in the dark until they finish.

By doing this you are exposed to a far bigger risk: Your generator neutral pole does not make in the generator switch. Now your touch voltage rises due to you unorthodox neutralizing approach.

There are risks associated with switching neutrals particularly from generators and even more so with 3 phase generators. Did you ever see what happens when the neutral fails but the phase(s) don't? I have and its not nice! It can cause a lot of damage.

My risk is far less which is that ESBN act in a very unprofessional manner. If I was genuinely concerned about this I would simply install a neutralization point customer side as this presents no real danger.

Tuco88

A silly question but Is the Neutral and Earth not at a common point in every generator? For it to be a PE does it not have to join to the neutral at some point? So connecting a genny to the house you would have connected 2 "neutralising" points regardless... The ESB one at the meter, and now the generator PE and N at the generator itself.

If the ESB neutralising link failed at some point or it was a TT system (new fuseboad never neutralised correctly 60/70s job) a fault in the generator could result in a live Neutral wire on the ESB side ?

Just asking ðŸ˜

2011

Tuco88 wrote: »

A silly question but Is the Neutral and Earth not at a common point in every generator?

No.

For it to be a PE does it not have to join to the neutral at some point?

Yes at the neutralizing point. This is at the ESB cut out (my way) or in the generator plug (karolaug's way) or at the generator (Sir Liam's way).

So connecting a genny to the house you would have connected 2 "neutralising" points regardless...

Not if done my way.

Edit:

If the ESB neutralising link failed at some point or it was a TT system (new fuseboad never neutralised correctly 60/70s job) a fault in the generator could result in a live Neutral wire on the ESB side ?

The ESB neutral is still connected to earth at the transformer. As stated if this was a real concern it would be possible to neutralize on the customer side. This is not an argument for not switching teh neutral, it is an argument for a redundant neutralizing point.

For all this discussion about the neutraliziation point being on the ESB side everyone is ignoring:

1) The real risk with a neutral on a TNCS system is a broken neutral on the ESB side. This has happened many times and is nasty.
2) Having more than one neutraliziation point within an installation is not that big a deal.
3) The neutral being switched by the generator changeover switch is a myth if you do it in the way described in this thread.
4) Switching generator neutrals is not without risk.

Tuco88

Points taken, for clarity... say you have a generator on a car trailer connected to the house. (No earth rod installed on the generator) and the neutral is not switched via the isolator.
Neutralizing is done at the ESB meter only as always.
A broken neutral occurs at the plug/socket for the generator. Is the neutral bar now live with the MET and so the ESB supply neutral wire coming in?

With the Neutral and Earth not ever being common on the genny side how can a short circuit happen??

If we had broken the ESB neutral via the C/O switch would we have not have protected people working on the lines from a shock anyway?

2011

Tuco88 wrote: »

Points taken, for clarity... say you have a generator on a car trailer connected to the house. (No earth rod installed on the generator) and the neutral is not switched via the isolator.

Neutralizing is done at the ESB meter only as always.
A broken neutral occurs at the plug/socket for the generator.

So you are now open circuit with the generator so no current flows.

Is the neutral bar now live with the MET and so the ESB supply neutral wire coming in?

The neutral bar is at 0 volts with respect to earth thanks to the neutralizing link and the earth rod. Both are connected to the MET.

With the Neutral and Earth not ever being common on the genny side how can a short circuit happen??

Between neutral and phase at the genny.

If we had broken the ESB neutral via the C/O switch would we have not have protected people working on the lines from a shock anyway?

1) The point is the changeover switch doesn’t really break the neutral. The genny neutral is connected to the genny earth. The genny earth is connected to the MET and this is commuting the ESB neutral. Therefore both neutral bars are connected to each other via earths.

2) The ESB neutral is connected to earth at the traffo, at the MET thanks to the earth rod and by the ESB worker. So where is the risk?

Tuco88

Wouldn't the Neutral bar and earth bar rise to a 230v potential? From the loads in the house say immersion heater lights...? Obviously not working or drawing a current now with the open circuit neutral at the genny socket.

The generator is not connected to the mass of ground its on tyres and no earth bar. We have no neutral to earth link at the genny, And a live neutral wire going back out to the ESB

Is this not the same sorta situation as cutting the main ESB neutral to a house expect we would have the Earth rod in that case?

2011

If the genny is not connected to earth at any point then it will have no reference to earth, it just “floats”.

Reisers.

You're going to need an RCD for Automatic disconnection with a small generator feeding into a domestic installation and it won't operate with the single pole changeover,its looking into a N-E short

Small Genset needs spiking and N-E connection>RCD> 2 pole changeover

Reisers.

The above and people applying voltages to N-E with dual voltage centre tapped generators would be the problems.

Only proper genset is a fixed standby generator and 1 N-E installation link in standby operation.

Too many variables leaving a plug for an unknown generator

2011

Reisers. wrote: »

You're going to need an RCD for Automatic disconnection with a small generator feeding into a domestic installation

I don't suppose you have any link to back this up?

and it won't operate with the single pole changeover,its looking into a N-E short

Most homes in Ireland are TNCS which means they are neutralized yet there is no issue with protecting all final circuits with RCDs.
Why do you think this is?

Clue: The neutralizing point is upstream of the RCDs

You seem to be confused about how RCDs work. Whether a neutral is switched or not will not have a bearing on whether they work or not.

I find it strange that you are proposing using a double pole changeover switch but you only plan to switch one pole

Small Genset needs spiking and N-E connection>RCD> 2 pole changeover

I'm going to assume you mean a earth electrode? Already discussed, if you look back in the thread you will see that everyone agrees that this is best practice. The frame of the generator should be connected to the MET and it would be best to connect it to a local earth electrode(s). This becomes more and more important the larger the generator gets and the further away from the MET it is.

The above and people applying voltages to N-E with dual voltage centre tapped generators would be the problems.

In Ireland we use a 230V single phase supply that has a neutral at 0V with respect to earth. So the "less conventional" dual voltage generators that you seem to have found would not be compatible regardless of whether the neutral is switched downstream or not. It would not be a good idea to try to use one of these generators as a standby generator so designing a wiring system to suit is of no benefit.

Only proper genset is a fixed standby generator and 1 N-E installation link in standby operation.

I think that everyone agree that this is best.

Reisers..

I'll go again with that for information purposes

Genset RCD providing ADS is upstream of changeover switch- ie upstream of any N-E link

Consumer RCDs are downstream of changeover switch at DBs- downstream of Neutralizing link

ET101:2008
411.4.3,411.4.5

ET210:2003 13.7

In the normal TN-C-S system,protection against electric shock in the case of a fault requires discoinnection by overcurrent protection......

If a fault should occur when an installation is being supplied by a standby generator ,the generator will normally not have the capacity to supply the value of current neccessary to cause tripping of the fuse or mcb within the prescribed times....

In such cases protection can only be provided by RCDs..

This protection should be arranged to come into effect ONLY whilst the installation is being supplied by the standby generator

2011

What does any of the above have to do with your proposal of installing a 2 pole changeover switch and wiring it so that only one pole actually switches?

You do know that RCDs don't provide over current protection?

Reisers..

2011 , i'm providing an alternative viewpoint on changeover of portable generators

i have provided all the relevant information to clarify to fully support and clarify the point i made on RCDs and ADS from the rules

maybe study it before retorting

2011

Reisers.. wrote: »

2011 , i'm providing an alternative viewpoint on changeover of portable generators

i have provided all the relevant information to clarify to fully support and clarify the point i made on RCDs and ADS from the rules

maybe study it before retorting

You have provided many alternative viewpoints but when questioned on them instead of responding you come up with new alternative viewpoints. None of your posts have been deleted or edited by mods to date however this will have to change if you continue in this way. Please respond to questions before posting more alternative view points.

Debate is most welcome, but it has to be a two way street.