Whilst we're on the subject of bonding...

[bigspark17]

I do, you dont!

 

[Leesparkykent]

It amazes me how there is so many qualified sparks out in the field that can't get their head around the subject of bonding lol

 

[Simonslimline]

We all know its a secret dark magic.

 

[davesparks]

Water is not conductive however any impurities dissolved in it will make it slightly conductive.

Experimentation has proved that a 22mm plastic pipe of 600mm length is enough to provide a fully insulated section between 2 copper pipes due to the resistance of the mass of impure water contained within it.

 

[davesparks]

Well im affraid sir your very wrong!

Water is made up of co-valently bonded hydrogen and oxygen atoms with no overall charge so electricity cannot flow through water alone. However that co-valent bond can be broken by a high enough voltage which will release the hydrogen and oxygen atoms in their gaseous form.

The addition of other substances with ionic bonds dissolved in the water results in charged ions being free to move in the water and this electricity can flow although it will have a relatively high resistance.

 

[bigspark17]

If in doubt then insulation test at 500v from MET to part in question <22k ohms bond if not NO NEED! If an installer wanted to he can nothing in bs7671 to say you cant!

 

[DPG]

If in doubt then insulation test at 500v from MET to part in question <22k ohms bond if not NO NEED! If an installer wanted to he can nothing in bs7671 to say you cant!

But you may make the installation more dangerous if you bond unnecessarily. Daz

 

[bigspark17]

But you may make the installation more dangerous if you bond unnecessarily. Daz

Would you care to elaborate on that??

 

[DPG]

Would you care to elaborate on that??

You are effectively making whatever it is that you have bonded a part of the electrical installation. For example, a metal sink - this cannot introduce a potential (even earth potential), and so is not extraneous and should not be bonded. You would not be making things safer by bonding it. Daz

 

[andyb]

1) i wouldnt say that two metallic parts that are 1666 ohms apart are at substantially the same potential, despite our interpretation of reg 415.2.2

2)Thats what i don't understand; - having 1666 ohms between an exposed conductive part and an extraneous conductive part during fault conditions will give a voltage approaching mains - depending on the circuit impedance of course.

cheers

sam

1/ They're not substantially the same Sam. The 1667 is to determine whether bonding is required in the first place. If they were not bonded but the circuits were protected by a 30ma rcd then if the resistance between them was less than 1667 ohms then the touch voltage between the two would be 50v or less, so there would be no requirement to bond.

2/ Not if there's a 30ma rcd, it will trip. If there is no rcd then you do not use 1667, you have to bond regardless.

 

[bigspark17]

Absolutely not.. Diferent ph levels and salts in water can make it more or less conductive according to levels.. What is stopping the water board putting conductive pipe joint underground and then this becoming extraneous conductive.. Small copper pipe after stop tap earth to MET no PD between earths in installation, tick jobs a good one!

You are effectively making whatever it is that you have bonded a part of the electrical installation. For example, a metal sink - this cannot introduce a potential (even earth potential), and so is not extraneous and should not be bonded. You would not be making things safer by bonding it.
What would you be giving it a PD too, as everything that introduces a earth path must be bonded!!

 

[DPG]

Don't understand that comment, sorry. Daz

 

[Deleted member 9648]

You are not Cockburn are you?

 

[Midwest]

Actually, water does not conduct electricity contrary to popular belief.

Thanks, my statement wasn't factual. However, water is more conductive than fresh air, hence the precautions taken in special locations.

 

[Midwest]

You don't.

If conditions are as described in reg 528.3.4, then '(ii) fault protection shall be afforded in accordance with the requirements of Section 411.'

Then bonding of metal pipes with plastic service supply, may be required.

 

[Midwest]

If conditions are as described in reg 528.3.4, then '(ii) fault protection shall be afforded in accordance with the requirements of Section 411.'

Then bonding of metal pipes with plastic service supply, may be required.

Sorry tried to do that multi quote thing, this was in response to #44

 

[telectrix]

You are effectively making whatever it is that you have bonded a part of the electrical installation. For example, a metal sink - this cannot introduce a potential (even earth potential), and so is not extraneous and should not be bonded. You would not be making things safer by bonding it.
What would you be giving it a PD too, as everything that introduces a earth path must be bonded!!

what if the metal sink has a metal waste, going into the ground?

 

[DPG]

Thanks for adding that complication Tel ☺

 

[Midwest]

what if the metal sink has a metal waste, going into the ground?

Will it need a soakaway?

 

[Midwest]

^^^^^^
bigspark17 never said that, wots going on mods

 

[Richard Burns]

click the multi quote button at the bottom of every post you wish to reply to and then click on reply with quote.

 

[Midwest]

click the multi quote button at the bottom of every post you wish to reply to and then click on reply with quote.

Hmmmm, that must be the problem then. I ain't got no multi quote button. Note to oneself, switch to Chrome.

 

[Richard Burns]

You have not got this button? which gets a tick beside it when clicked

 

[Midwest]

I have but nothing seems to happen when I click it. Got other problems like not all keys strokes showing on screen. Been told to use Chrome.