TOUCH VOLTAGE

[Manator]

I really do not understand where you are going or coming from, we do not make things up as we go along 50v is stated as a "safer" option, by design we are required under the regulations to limit any voltage that can be touched directly or indirectly. Equipotential bonding is a proven method of reducing this potential differences and touch voltages in association with protective devises.

The installation does not have to comply "only" in a special location, but comply throughout its total components.

One perfect example of this would be a TT install.

By your argument a TT install would be a special location.

 

[park1]

In general installation the touch voltage will be decided by R2 and the system impedance, RCDs don't limit the touch voltage, it obeys ohms law.

0.4 sec 240 volts, 95 percent of the population. Bonding limits the magnitude. The touch voltage will be as above.

 

[park1]

I really do not understand where you are going or coming from, we do not make things up as we go along 50v is stated as a "safer" option, by design we are required under the regulations to limit any voltage that can be touched directly or indirectly. Equipotential bonding is a proven method of reducing this potential differences and touch voltages in association with protective devises.The installation does not have to comply "only" in a special location, but comply throughout its total components.

One perfect example of this would be a TT install.

By your argument a TT install would be a special location.

If the installation requires 415 then the touch voltage is limited to 50v.

By nature lots of TT installations have low touch voltages due the Earthingt impedance

---------- Post Auto-Merged at 23:24 ---------- Previous post was made at 23:21 ----------

I thought we were harmonised now :slap

When biegelmeier and lee conducted there tests the voltage was 240

 

[Manator]

Far too many people rely on 415 as an excuse for poor design, lets face it.

You should have been around when I debated wiring a domestic without the requirement of a single RCD.

 

[SPECIAL LOCATION]

I see no limits on touch voltage for general installations?

wot.. no book? :|

If you read back the thread that you have raked up....

I gave a page number for the red book...

The new money equivalent is if you start reading on page 66 of the big green book....

415.2 Additional; protection: Supplementary equipotential bondingNote 3:

Supplementary bonding may involve the entire installation, a part of the installation, an item of equipment or a location

now go down to 415.2.2

Where doubt exists about the effectiveness of supplementary eqipotential bonding, it shall be confirmed that the resistance between simultaneously accessible exposed conductive parts.......blah blah blah.....

less than or equal to 50v in ac systems

that was page 59 of the red one...

like wot I said in my earlier post....

The entire installation or part of...

covers just about anywhere that it may be applicable no?

p.s.

We are NOT just talking about domestic only jobs here!

 

[park1]

I'm not saying we shouldn't consider touch voltage in general installations, but when you have a tncs and an abundance of twin and earth with a reduced cpc, touch voltages will be in excess of 100 volts in most instances even with bonding in place.

---------- Post Auto-Merged at 23:37 ---------- Previous post was made at 23:34 ----------

wot.. no book? :| If you read back the thread that you have raked up....

I gave a page number for the red book...

The new money equivalent is if you start reading on page 66 of the big green book....

now go down to 415.2.2

that was page 59 of the red one...

like wot I said in my earlier post....

The entire installation or part of...

covers just about anywhere that it may be applicable no?

p.s.

We are NOT just talking about domestic only jobs here!

Specs, I am aware of 415, but in a general installation your not required to install supplementary bonding. I'm referring to general installations.

 

[Manator]

Oh great, I have a book with 464 pages and was going to take it page by page and you go and give him all the page numbers.

Oh well back to normality, surely a reply would be futile now?

 

[park1]

Excluding 415 and certain special locations, there is no specific limit placed on touch voltage. We need to ensure disconnection and limit magnitude via bonding.

 

[Manator]

What would happen if your meter maid came to read your gas meter at a time when a fault was in progress? The meter will probably be by the entrance, or even outside the property, out side is a special location, but in your hallway? Yet touch voltages will still apply.

 

[steptoe]

I'm not saying we shouldn't consider touch voltage in general installations, but when you have a tncs and an abundance of twin and earth with a reduced cpc, touch voltages will be in excess of 100 volts in most instances even with bonding in place.---------- Post Auto-Merged at 23:37 ---------- Previous post was made at 23:34 ----------

Specs, I am aware of 415, but in a general installation your not required to install supplementary bonding. I'm referring to general installations.

:slap

 

[park1]

415.2.2, additional protection, not required for general installations where ads is applied, only where disconnection timed can not be met.

 

[SPECIAL LOCATION]

I'm not saying we shouldn't consider touch voltage in general installations, but when you have a tncs and an abundance of twin and earth with a reduced cpc, touch voltages will be in excess of 100 volts in most instances even with bonding in place.

BUT.....

that was not the OP's question..

he asked someone to explain touch voltage...

You assumed it was purely a domestic T&E installtion......

then made a factually incorrect statement that it only applied to special locations.... (oh... thats a good name :Blushing )

Which others pointed out was wrong....

The OP's question had been answered and references given.....

But it could be argued that one person is trying to make a different question out of someones else's thread!!!

:C

PS......

I cannot find the definition of a general installation in Part 2....

is that one with only PVC T&E

and a 2 up 2 down semi with Mr & Mrs 50+ with 2.5 kids 1 dog and a ford Mondeo?????

:coat

 

[Manator]

OK, the debate can not go forward, for all those who really do want to know, touch voltage is not just for special locations, it applies to all parts of the installation.

 

[park1]

I'm not assuming anything, 415 aside and yours truly, where placed a limit on touch voltage?

Just making a point that the 50 v it not a guarantee touch voltage, unless you design so or use 415, I can't see why people can't grasp it.

 

[SPECIAL LOCATION]

OK, the debate can not go forward, for all those who really do want to know, touch voltage is not just for special locations, it applies to all parts of the installation.

You are correct sir....

If it were not a general rule...

It would only be in one of the chapters relating to special locations wouldn't it Manator?

 

[Manator]

Indeed it would Mr Special Location.

 

[Mr Smith]

mr $park

mr smith is not an electrician

as he has previously stated

however

mr smith does own a copy of bs7671 2011

as a useful reference

in arbitration

so perhaps mr smith is stupid

but the section of the book where

411

415 etc

are located

is the section for protection against electric shock

and that regulations pertaining to

special locations

were in another part of the book

if this is indeed the case

as appears to be borne out by the chapter heading on page 51

then your supposition that this only refers to special locations

appears inherently flawed

questions are an integral part of the forum

however repeatedly posting the same words in a different order

is unlikely to make them become true

for what it is worth

the observation of mr smith

is that my esteemed colleagues

and other forum members

may well be correct in their suppositions

which

by definition

suggests mr $park may be

meowing up the incorrect flagpole

mr smith

 

[park1]

Oh dear, no one knows how to calculate touch voltage.

I'll set you all an task, then we will see what sort of touch voltages can be present where 415 is not utilized and the designer hasn't specifically designed for a certain touch voltage, I'll use the circuits within the onsite guide

---------- Post Auto-Merged at 00:08 ---------- Previous post was made at 00:06 ----------

Humble pie anyone?

 

[Mr Smith]

mr $park

could you explain

why

you are wishing to ignore a specific regulation

mr smith was under the impression

that the regulations were used

en masse

rather than picking and choosing which ones to use

as an aside

mr smith does

not

know how to calculate touch voltages

therefore

mr smith hires the services of someone who does

when necessary

mr smith

 

[Manator]

Oh dear, no one knows how to calculate touch voltage.I'll set you all an task, then we will see what sort of touch voltages can be present where 415 is not utilized and the designer hasn't specifically designed for a certain touch voltage, I'll use the circuits within the onsite guide

You will be wasting your time simply because you choose to ignore the basic principles of the regulations.

The wiring regulations do not start at the chapter you are confident with, they start at the beginning. Every regulation is intertwined and cross referenced throughout the whole regulations.

Ignorance of the basic facts, and principles, would make what ever you post from this day forward nothing more than a personal jolly on your part, and will not now be taken seriously by any member of this forum.