No main equipotential bonds

[atm84]

There are no main equipotential bonds to water or gas.

What risk does this pose in layman terms?

 

[Simonslimline]

Have you tested to see if they are extraneous?

 

[kenny7askew]

pre cut out break in neutral could lead to harmful voltage on casings of class I equipment,this could be touched at same time as pipes/metal if they are at earth potential-extreaneous

 

[Barry White]

Its purpose is to keep all conductive exposed parts at the "SAME" potential or as close to it as possible so as its bonded to earth if it has a potential because of a fault the earth in the zone should be at the same or close to the potential so reduce or eliminate the risk of a shock.
In layman terms without it a fault could make the pipes live resulting in an electric shock.

 

[happysteve]

In addition to post #3: if they are extraneous, then for the duration of an earth fault (short circuit to earth) - which could be up to 5 seconds for a distribution circuit (or a final circuit over 32A) - the exposed-conductive-parts (bits of metal that are part of your electrical installation, like the casing of class 1 equipment) will be at a different voltage to extraneous-conductive-parts (your water/gas pipes) which is a shock risk.

If RCDs for additional protection are present, the risk associated with the above is significantly reduced... in practice, the RCD will almost certainly trip and clear the fault a lot faster than the OCPD.

 

[Pete999]

There are no main equipotential bonds to water or gas.

What risk does this pose in layman terms?

I refer you to OSG PAGE43

 

[Deleted member 9648]

Its purpose is to keep all conductive exposed parts at the "SAME" potential or as close to it as possible so as its bonded to earth if it has a potential because of a fault the earth in the zone should be at the same or close to the potential so reduce or eliminate the risk of a shock.
In layman terms without it a fault could make the pipes live resulting in an electric shock.

This is incorrect and misleading. The sole purpose of main bonding is to prevent a rise in voltage on conductive parts (read the definition of a conductive part) during a fault, resulting in a shock risk to a person in simultaneous contact with a metallic service introducing the general mass of earth into the property. It's nothing to do with pipes becoming live.

 

[andyb]

Its purpose is to keep all conductive exposed parts at the "SAME" potential or as close to it as possible so as its bonded to earth if it has a potential because of a fault the earth in the zone should be at the same or close to the potential so reduce or eliminate the risk of a shock.
In layman terms without it a fault could make the pipes live resulting in an electric shock.

This is incorrect and misleading. The sole purpose of main bonding is to prevent a rise in voltage on conductive parts (read the definition of a conductive part) during a fault, resulting in a shock risk to a person in simultaneous contact with a metallic service introducing the general mass of earth into the property. It's nothing to do with pipes becoming live.

Arnt you both saying the same thing?

 

[Barry White]

This is incorrect and misleading. The sole purpose of main bonding is to prevent a rise in voltage on conductive parts (read the definition of a conductive part) during a fault, resulting in a shock risk to a person in simultaneous contact with a metallic service introducing the general mass of earth into the property. It's nothing to do with pipes becoming live.

I dont understand I am misleading and you arnt yet we are singing from the same hymn sheet is a pipe that should be bonded not a conductive part? I didnt quote rules or regulations I said it in laymans terms as asked.

 

[Pete999]

All right you have to join the main water and gas pipes with a bit of 10mm earth cable to ensure they are at the same potential as earth.

 

[Hellmooth]

This is incorrect and misleading. The sole purpose of main bonding is to prevent a rise in voltage on conductive parts (read the definition of a conductive part) during a fault, resulting in a shock risk to a person in simultaneous contact with a metallic service introducing the general mass of earth into the property. It's nothing to do with pipes becoming live.

I think he means the pipe would rise to the same potential.

 

[Deleted member 9648]

I dont understand I am misleading and you arnt yet we are singing from the same hymn sheet is a pipe that should be bonded not a conductive part? I didnt quote rules or regulations I said it in laymans terms as asked.

But it's wrong.
A pipe is not a conductive part,a conductive part is a metallic part of the electrical installation which would not normally be live but which may become so under fault conditions. A metallic non electrical service coming into a building from externally is likely to be at earth potential by virtue of being in contact with the general mass of earth,and will remain at earth potential if it is not connected to conductive parts. Explain how a pipe will become live if it is not bonded? If you are going to explain something in laymans terms at least get it right.

 

[Barry White]

It may be at earth potential but is it equipotential to the rest of the earthed metalic electrical instalation. It needs to be kept equipotential in case a fault occurs on an immersion heater etc. Hence they need to be joined.

 

[atm84]

But it's wrong.
A pipe is not a conductive part,a conductive part is a metallic part of the electrical installation which would not normally be live but which may become so under fault conditions. A metallic non electrical service coming into a building from externally is likely to be at earth potential by virtue of being in contact with the general mass of earth,and will remain at earth potential if it is not connected to conductive parts. Explain how a pipe will become live if it is not bonded? If you are going to explain something in laymans terms at least get it right.

You are missing the word 'exposed'. You mean to say 'an exposed conductive part'.

 

[Deleted member 9648]

It may be at earth potential but is it equipotential to the rest of the earthed metalic electrical instalation. It needs to be kept equipotential in case a fault occurs on an immersion heater etc. Hence they need to be joined.

But how does it 'become live' if it's not bonded?

 

[Deleted member 9648]

You are missing the word 'exposed'. You mean to say 'an exposed conductive part'.

Well picked up atm,just given myself a slap.

 

[Barry White]

Yes....but how does it 'become live' if it's not bonded?

in case a fault occurs

 

[Deleted member 9648]

in case a fault occurs

Unbelievable.
And you claim to be an electrical engineer?

 

[Hellmooth]

in case a fault occurs

It isn't even a relevant answer, the question was how would it become live unless it was bonded.......ie if it wasn't bonded it couldn't rise to mains potential.

 

[Barry White]

Unbelievable.
And you claim to be an electrical engineer?

So you think all earths are at the same potential then so you will never get a potential between 2 earth rods spaced apart or a rod and a pipe in the ground at the front and rear of the property.

Dont want to fight would discuss seems if you dont agree, you question who or what I am either discuss with facts or I will ignore you