possible grounding issue

[Jimbob18]

Hi folks, I am getting sparking intermittanly from my condensation pipe out.
It seems to be when there is a driving rain, this continues even when I switch off the boiler at the power switch next to it. Can anyone give me any clues why this would be happeining. The gas engineer has never seen this before.

thanks in advance

 

[bernardgreen]

The condensate drain pipe should be plastic. The condensate is mildly acidic and corrodes copper pipe.

The condensate drain pipe, if metal all the way to the boiler, should be connected to the equipotential "earth" of the electrical supply. This is often derived from the neutral of the supply to the house and not from true ground.

Therefore the condensate drain pipe may not be at true ground voltage and this could cause sparks between the condensate drain and an object in contact with true ground.

 

[electronicsuk]

There must be a fair bit of difference in potential between true ground and the earth potential of the wiring within the property. I suspect you don't have the correct bonding in place, perhaps coupled with a secondary fault that's causing a rise in voltage on the earth conductor. You should really get a good electrician in to look at this ASAP.

 

[Peet]

If you swap to a plastic condensate pipe consider going for a 32mm dia pipe rather than the 21.5mm one. The 21.5mm ones have a habit of freezing during cold weather as they leave the property depending on the way the boiler ejects its condensate.

 

[bernardgreen]

If the "plumber" fitted a copper condensate drain then he may also have bodged the electrics. A spark suggests a serious problem exists and a competant electrician is needed.

Freezing of condensate was overlooked / ignored in the rush to get condensing boilers in service. The small trickle of condensate does not have enough heat to travel more than a few metres before it cools. and in cold weather it freezes in less than a metre of cold pipe. Lack of foresight by "plumbers" add to the problem.

A badly installed large bore condensate drain can freeze quicker than a small bore as cold air can more easily enter the pipe to freeze the water even further up the pipe.

If there is no way to keep the entire length of the pipe in non freezing locations then consider electric trace heating. Essential if the house might be left un-occupied during freezing weather. Or consider running a second pipe next to it in lagging. When it freezes hot water ( from a kettle etc ) can then be run through the second pipe to thaw out the condensate. After use the "heating" pipe should be blown dry to prevent that freezing before it is needed again.

 

[RMS]

The condensate drain pipe, if metal all the way to the boiler, should be connected to the equipotential "earth" of the electrical supply.

Surely this would depend on the location of the pipe externally to the installation and if it is capable of introducing a potential before we can class it as extraneous.

By equipotential "earth", do you mean "protective bonding"?

 

[bernardgreen]

The condensate drain pipe, if metal all the way to the boiler, should be connected to the equipotential "earth" of the electrical supply.

Surely this would depend on the location of the pipe externally to the installation and if it is capable of introducing a potential before we can class it as extraneous.

The regulations say that even a plastic water pipe which comes into a building and then inside the building is connected to a metal pipe will make that metal pipe capable of introducing a potential. So any metal pipe passing through the wall has to be considered as capable of introducing a potential through the wall and into the equipotential zone.

By equipotential "earth", do you mean "protective bonding"?

There isn't really a difference as "protective bonding" is almost always connected to the "earth" of the electrical supply via metallic pipe work.

 

[RMS]

The regulations say that even a plastic water pipe which comes into a building and then inside the building is connected to a metal pipe will make that metal pipe capable of introducing a potential.

Do the regulations state that this automatically requires main protective bonding?

So any metal pipe passing through the wall has to be considered as capable of introducing a potential through the wall and into the equipotential zone.

Does that include the pressure relief pipe that gereally sticks out the wall about 4inch.

There isn't really a difference as "protective bonding" is almost always connected to the "earth" of the electrical supply via metallic pipe work.

I take your point but 'earth' and 'bonding' have two different definitions in BS7671.

 

[EFLImpudence]

The condensate drain pipe, if metal all the way to the boiler, should be connected to the equipotential "earth" of the electrical supply. This is often derived from the neutral of the supply to the house and not from true ground.

As you correctly state the pipe should be plastic so what is the point of this instruction?

By equipotential "earth", do you mean "protective bonding"?

There isn't really a difference as "protective bonding" is almost always connected to the "earth" of the electrical supply via metallic pipe work.

There is a difference.
Its purpose is not the same therefore bonding should be called bonding so that we know what is meant.

It is not 'earthed' therefore we do not measure its Zs to determine if the opd will operate in time.

 

[Peet]

By equipotential "earth", do you mean "protective bonding"?

There isn't really a difference as "protective bonding" is almost always connected to the "earth" of the electrical supply via metallic pipe work.

There is a difference.
Its purpose is not the same therefore bonding should be called bonding so that we know what is meant.

It is not 'earthed' therefore we do not measure its Zs to determine if the opd will operate in time.

I think you're both right.
You both see the same thing from slightly different angles. I think Bernard is looking at it from an overall point of view. But I can see the point about usage of terms and what the 'local' system is designed to achieve from EFLI's point of view too. I'm sometimes guilty of confusing the two. To me there's no confusion in the understanding I just sometimes refer to it as it is an overall system.

 

[bernardgreen]

I think Bernard is looking at it from an overall point of view.

My point of view is they are electrically connected together be it by electrical wires or conductive water and/or gas pipes.

But I can see the point about usage of terms and what the 'local' system is designed to achieve from EFLI's point of view too.

Which I also understand but by giving different parts of the same circuit different names and by implication different and separate funtions there is plenty of scope for confusion.

I have heard electricians saying there must be no wire connecting a radiator to the main earth terminal as it is against "the rules" and by implication could create a hazard of un-necessary earthing. But they overlook the fact that there is a connection from the radiator to the main earth terminal via central heating pipes to the boiler and from onwards via at least two paths the main earth terminal. Path 1 is the CPC of the electrical supply to the boiler and path 2 is the water and gas pipes and the main bond of these pipes to the main earth terminal.

 

[EFLImpudence]

I think Bernard is looking at it from an overall point of view.

My point of view is they are electrically connected together be it by electrical wires or conductive water and/or gas pipes.

But they do different things.

But I can see the point about usage of terms and what the 'local' system is designed to achieve from EFLI's point of view too.

Which I also understand but by giving different parts of the same circuit different names and by implication different and separate funtions there is plenty of scope for confusion.

You mean like Line, Neutral and CPC.

I have heard electricians saying there must be no wire connecting a radiator to the main earth terminal as it is against "the rules" and by implication could create a hazard of un-necessary earthing.

It could. It depends whether bonding is necessary.

But they overlook the fact that there is a connection from the radiator to the main earth terminal via central heating pipes to the boiler and from onwards via at least two paths the main earth terminal. Path 1 is the CPC of the electrical supply to the boiler and path 2 is the water and gas pipes and the main bond of these pipes to the main earth terminal.

But now you are giving different parts of the same circuit different names.

Bonding and Earthing have different purposes.
The difference is important.

 

[ban-all-sheds]

EFLi - it is abundantly clear, demonstrated by many posts over a considerable period of time, that bernard simply does not get the difference between earthing and bonding, nor can even comprehend that there is a difference.

 

[bernardgreen]

EFLi - it is abundantly clear, demonstrated by many posts over a considerable period of time, that bernard simply does not get the difference between earthing and bonding, nor can even comprehend that there is a difference.

I do comprend very clearly the difference between earthing and bonding. Mainly because I have worked with radio equipment where due to the high frequencies involved a continuous but not straight length of copper wire may have a high potential ( relative to ground ) at one end and be connected to ground at the other end. At high frequencies a bend in a wire has a significant impedance due to the inductance created by the bend.

A single continuous length of wire can be a high frequency bonding conductor at one end and a separate bonding conductor at the other end but is an earthing conductor at 50 Hz along its entire length if any part of it is connected to "earth".

At the hot end a straight length of it can be bonding items together so there is no, or very little, potential difference between them. They may still be many volts ( at high frequency ) above the ground potential at the other end of the wire. The wire will also provide a safety earth ( at 50 Hz and very low impedance ) for anything connected to it.

There are also bonding conductors that are used to bond items together to prevent those items having different high frequency voltages on touchable surfaces. In some situations it is necessary to ensure these are not connected to earth by anything, cable, pipe, framework etc. Electrical safety "earths" are completely separated from the bonding.

In the domestic situation of 50 Hz supply unless all pipe work is plastic and all liquids in all those plastic pipes are non-conductive then for all practical purposes bonding and "earthing" are one and the same galvanic (conductive metallic ) circuit.

 

[RF Lighting]

I do comprend very clearly the difference between earthing and bonding

bonding and "earthing" are one and the same

You do NOT understand the difference. The only thing the same about earthing and bonding is the colour of the wire that is used.