L&N - E insulation testing

[monkey5]

finally got round to testing my own house today.

IR testing the ring live-neutral and got a reading 0.7M ohms obviously a fail. everything was disconnected including all FCUs. tested live/neutral - earth and got

299. would i need to investigate it or would it be the reading for live/neutral - earth be acceptable, if so hows this written on cert and would i need to comment why ive done it this way?

to be honest i will investigate it anyway but just curious of what other people think/would do.

the reason i tested it is because im going to change board to 17th eventually.

thanks wayne

 

[Andy™]

you shouldnt really do L to N on existing because you cannot guarantee everything has been disconnected, and putting 500v there can do damage. thats why its acceptable to do l&n to e. chances are there is a neon, aerial booster or something still connected somewhere

 

[monkey5]

to be honest always do it on 250v first and if thats clear i do 500v. definitaly nothing still connected as its my house so know where everything is.

if you did l&n -e how would it be written on cert?

 

[SPECIAL LOCATION]

to be honest always do it on 250v first and if thats clear i do 500v. definitaly nothing still connected as its my house so know where everything is.if you did l&n -e how would it be written on cert?

1/

Assuming you are using certs to the model in BS7671...

Just write your >299Mohm in the Live-Earth column

and pun 'LIM' (Limitation) in the Live-Live column.

In the comments box write a note about Limitation to Live-Live testing due to equipment vulnerable to testing still connected to circuit.

2/

0.7Mohm live-live.....

IMHO

This would Not be part of a physical cable run...

because T&E has Earth in the middle..

so a 0.7 Live-Live would have to go across the bare CPC so you would have low Live-Earth as well..

So could be possibly be Damp across termination at a J-Box or accessory?

0.7Meg ohms would appear high for something connected

i.e. V/R=I.......

It would be a very very low current usage item!?

230v/700,000ohm 0.0003A!!? :| ?:|

 

[green-hornet]

Good post with one possible correction you have overlooked special ,live+live, is only for 3 phase and not single phase

Knowing your knowledge I would assume it is a typo, but could mislead following readers.

 

[Apache]

Good post with one possible correction you have overlooked special ,live+live, is only for 3 phase and not single phaseKnowing your knowledge I would assume it is a typo, but could mislead following readers.

now now GH, isn't the neutral strictly considered a live conductor.......

 

[green-hornet]

Problem is when you come to fill in the certs you will have

1,live to live

2,live to nuetral

3,live to earth

4, neutral to earth

Or more speciffically (spelling allowed for)

1 line /line

2 line/ neutral

3 line /earth

4neutral/earth

Because in a domestic or single phase supply line/line is often not used and is filled out on the form as n/a.

This is because normally it is found in 3 phase supplies and not single.

 

[SPECIAL LOCATION]

Good post with one possible correction you have overlooked special ,live+live, is only for 3 phase and not single phaseKnowing your knowledge I would assume it is a typo, but could mislead following readers.

:|erm......

don't want to have a hairbrush throwing fight GH..

BUT...

No typo or overlooked items And NO misleading of others....

Unless your On-Site-Guide And/Or Guidance note 3 have different wording to mine??

Check page 84 One-Site Guide...

iii Insulation Resistance testing

Single Phase AND three phase Test between ALL the live conductors..

(Line & Neutral)

even got a colour picture... 10.6!B-)

And/Or

Page 141 one site guide Notes *9 & *10 Insulation resistance!......

Diss voltage sensitive devices OR test between Live conductors (Line & Neutral) connected together to earth.

The Above info is also found on pages

37 tho to 39 & page 94 of guidance note 3 respectively!!!

; )BlushingGuiness Drink

Or do you want to go for hair brushes at dawn?

we could meet in Dekes back garden..

P.S. NO hairdryers allowed!

] ]Blushing

shall I put me beer down now? :^O;\

 

[green-hornet]

I would blow you away with my super charged electronic controled hair dryer

]

Just wanted people to know that line/line is for 3 phase and not to be mistaken for line/ neutral.

Any way if we had a hairbrush fight admin two would win, even though she was not invited.

 

[Apache]

I would blow you away with my super charged electronic controled hair dryer ]

Just wanted people to know that line/line is for 3 phase and not to be mistaken for line/ neutral.

Any way if we had a hairbrush fight admin two would win, even though she was not invited.

You saying Admin 2 is full of hot air?! :^O

was nice knowing you.............

 

[green-hornet]

You saying Admin 2 is full of hot air?! :^O was nice knowing you.............

Lol no she is the master of the hairbrush and turbo dryer, and I quake at her every command(just like admin) though he would put up a good fight he could never win. :^O

Me? I am just a spot of dirt she would brush off her shoes

 

[SPECIAL LOCATION]

I would blow you away with my super charged electronic controled hair dryer ]

Just wanted people to know that line/line is for 3 phase and not to be mistaken for line/ neutral.

Any way if we had a hairbrush fight admin two would win, even though she was not invited.

Where's Line/Line given on model BS7671 forms?

Its a nice thought...

BUT... they just DON'T say "Line/Line"

they actually say "Live/Live" as in between Line & Neutral (part 2 definitions!)

OR.....

before they changed the flippin names..

you could always refer back to say the yellow book..

try Page 60 Yellow guidance note 3 16th ed

Figure 3 tests between what we used to call Phase & neutral conductors..

OR......

(come here theres more......)

try looking at the example filled out certs in the On-site-guide..

Page 156 Red O.S.G. Book

Page 148 Brown O.S.G. book

Page 129 Yellow O.S.G. book

They ALL shown Live/Live IS used on single phase insulation resistance testing...

As for Line/Line?, I am not sure which model forms you are suggesting this column is on?

because other than the minimum acceptable values, Insulation resistance testing has not changes between old & current regs....

Don't take my word for it.. check out the "books"....

612.3.1 Page 158 Big Red

713-04-01 Page 172 Big Brown

713-04-01 Page 155 Big Yellow

So I still stand by my earlier posts as ALL being factually correct for single phase..



Hair dryers... indeed? :|

I am going to borrow Dekes curling tongues! ]

 

[Andy™]

Good post with one possible correction you have overlooked special ,live+live, is only for 3 phase and not single phaseKnowing your knowledge I would assume it is a typo, but could mislead following readers.

i agree with specs - both line and neutral are 'live' conductors, so live-live would be line to neutral single phase, and line-line and line-neutral on 3 phase)

 

[green-hornet]

I only fill in the NICEIC forms so thats why I have said line/line etc etc.

I do know that these forms have extra boxes to fill in than the standard forms.

However I will concede as for hairbrush fights I have lost this one

Because by definition the neutral is and will always be classed as a "live".

 

[Doc Hudson]

Lol no she is the master of the hairbrush and turbo dryer, and I quake at her every command(just like admin) though he would put up a good fight he could never win. :^O Me? I am just a spot of dirt she would brush off her shoes

Saturday mornings reviewing what you night-shift gents, (apologies if any night-shift females have been posting), have been chatting on about, can be most enjoyable. Thank you.

Doc H.