Voltage on Sink (longish read)

[ProDave]

Dead link. this seems to be happening a lot lately. If anyone else can see the link, please re post it. Otherwise can you try again Lee?

 

[NozSpark]

He said,

 

[Doc Hudson]

Dead link. this seems to be happening a lot lately. If anyone else can see the link, please re post it. Otherwise can you try again Lee?

I can see the link. Is this any help Dave?

Doc H.

View attachment 3400

 

[Doc Hudson]

or..

 

[ProDave]

or..View attachment 3402

I can see that one, but not the one in the post above. I get "Invalid Attachment specified. If you followed a valid link, please notify the administrator" this happens quite a lot, that some can see an attachment, while others can't. Strange.

Anyway, that's not what I know of as a TNCS head, and there's no connection the the sheath. Looks like the DNO fitted the missing earth connection when they visited so hopefully that's the end of the floating earth issue.

 

[NozSpark]

Dave,

I think you need to put your glasses on,, have a look from the MET going left towards the service cable (perforated strap) ; )

 

[SPECIAL LOCATION]

Well I would still be interested to hear any answers from my post #9..... :C

Or post #16?????

Wouldn't a Ze / (Ra) test at the CU have confirmed if there was an earth path....

rather than getting the DNO out???

COPY post#9:-

Have any of these 'voltages' actually been measured with reference to incoming earth..i.e. wander lead to the sink and dishwasher....

For example...

Could be sink @ 0v and D/W @ 60v

or

sink @ 60v and D/W @ 0v

or

Sink @ 30v and D/W @ 30v

Would all give the same apparent fault potential between the two devices...

But need to know exactly whats what...

Remember there is NO specific requirement to supplementary bond sinks or draining boards...

top of Page 43 on-site-guide

You could be introducing a potential difference that wasn't there by bonding. :C

#16.....

Now... where does it say you need to maintain bonding continuity to a kitchen sink? :C

 

[lineman]

Thought that kitchen sinks need no bonding providing the rest of the installation complies with current regs. Await incoming.

 

[SPECIAL LOCATION]

Thought that kitchen sinks need no bonding providing the rest of the installation complies with current regs. Await incoming.

Indeed!....

that is what I said on my post #9

By bonding something that dose not need bonding you can be introducing an earth potential that could increase the risk of shock

rather than reduce the risk of shock!!

Some people have this confused idea that if its bonded it MUST be safer!!

 

[NozSpark]

I don 't think that kitchen sinks have ever required bonding

 

[Lee Sparks]

This bit of your post lends me to think that they have a TNS supply. It sounds like he's fitted a constant force spring around the service sheath.A PME or TNC-S (which are not the same thing BTW) earth would be connected within the service head.

This makes sense, i havent heard of a constant force spring, but the owner did mention the engineer said something about a "spring" thought she heard it wrong. Cheers.

---------- Post Auto-Merged at 08:10 ---------- Previous post was made at 08:08 ----------

I can see that one, but not the one in the post above. I get "Invalid Attachment specified. If you followed a valid link, please notify the administrator" this happens quite a lot, that some can see an attachment, while others can't. Strange.Anyway, that's not what I know of as a TNCS head, and there's no connection the the sheath. Looks like the DNO fitted the missing earth connection when they visited so hopefully that's the end of the floating earth issue.

Im guessing that its going to be alright now, im hopeing its fixed the issue, maybe the earth path wasent good enough before.

---------- Post Auto-Merged at 08:12 ---------- Previous post was made at 08:10 ----------

Well I would still be interested to hear any answers from my post #9..... :C Or post #16?????

Wouldn't a Ze / (Ra) test at the CU have confirmed if there was an earth path....

rather than getting the DNO out???

COPY post#9:-

#16.....

In my previous post, i mentioned i didnt carry out a Ze test, because i was not certain on what conductor was the earthing conductor.

Now the DNO has come and fixed an approved spring/clamp, its identified. When im due to go back there later on today, ill make sure ill do a Ze (thats already been done by the DNO ) for my own assurance.

As for the voltage measured between dishwasher & sink, i will conduct this test today & let you know.

Now when i say im testing if the sink is earthed or bonded, maybe im not useing the right terminogly.

But i carried out a test,a R2 test(long lead) on the sink, to make sure it had continuity with the MET , thus within a equipontential zone.That the exposed metalwork LEADING to the sink is bonded, not the sink itself.If thats clearer?

When i first looked at the job this wasent clear so i carried out the test to scrub that of the list.

 

[SLIPSHOD & SLAPDASH]

If you take a look at this thread i started a while back you can see a constant force spring and how it works http://www.talk.electricianforum.co.uk/your-pictures/17563-how-underground-cable-joint.html

 

[Lee Sparks]

Ahh, thats the one. nice to see one before its installed, many thanks.

Exactly the type they have used here, View attachment 3411

This is, in effect now a TN-S system?

I carried out a Ze on this system, result was 0.15 ohm, happy with that.

I next carried out a RCD test, x half, both 0 & 180, NO TRIP, fine.

x one, both 0 & 180, NO TRIP!

x five, both 0=18ms 180=28ms, fine. Fauly RCD?

No voltage detected between sink & dishwasher what so ever.

Earth continuity proven between earth pin of plug to dishwasher.

Now, i have a oldish multifunction that trips RCD's when carrying out Zs (sometimes Ze) and PSC/PFC.

So i couldnt get a reading without bridgeing out or removeing the RCD. When i looked at the board, i chickened out of messing with the RCD, thought i would borrow my friends all singing & dancing multifunction instead!

Wanted to check on the Zs before re-placing RCD.

Thats where im at now.(who cares?)

I started, so ill attempt to finish!

 

[NozSpark]

Lee,

It always was a TN-S from what I could tell from your photo, although I personally dislike perforated strap screwed underneath a MET as I've found that they become loose.

Did you check the RCD with the loads disconnected? Otherwise your tests are pretty meaningless I'm afraid

I can't remember if you've done a long lead from the MET to the sink and dishwasher,, if you haven't then I would check for continuity and voltage.

It might also help if you could connect an auto-ranging (with peak hold function) betweeen the dishwasher and sink for at least a full cycle.

 

[kme]

Lee:

If a test fails, don`t blindly carry on to the next one.

If the RCD didn`t trip at 1X; why test it at 5X? un-necessary risk.

You say your meter occasionally trips RCD on Ze test? Now I find that really scary, COS IT SHOULDN`T BE ENERGISED TO START WITH!

"You started"; but I`m not sure you can finish.

Thats where im at now.(who cares?)

Who indeed??

 

[Lee Sparks]

Lee,It always was a TN-S from what I could tell from your photo, although I personally dislike perforated strap screwed underneath a MET as I've found that they become loose.

Did you check the RCD with the loads disconnected? Otherwise your tests are pretty meaningless I'm afraid

I can't remember if you've done a long lead from the MET to the sink and dishwasher,, if you haven't then I would check for continuity and voltage.

It might also help if you could connect an auto-ranging (with peak hold function) betweeen the dishwasher and sink for at least a full cycle.

Hi Noz,

I tested the RCD with loads connected. We was taught at college to run a RCD test with the installation engergized, either a kettle lead from meter in a socket outlet or a 2 or 3 lead instrument at a lighting rose etc, so im not with you there?

I carried out a long lead continuity test from MET to dishwasher & sink, was proven.

Checked for voltage between sink/dishwasher, none measured. But i didnt check for voltage while the dishwasher was in operation/full cycle, just with the power on.

Thanks.

---------- Post Auto-Merged at 14:30 ---------- Previous post was made at 14:13 ----------

Lee:If a test fails, don`t blindly carry on to the next one.

If the RCD didn`t trip at 1X; why test it at 5X? un-necessary risk.

You say your meter occasionally trips RCD on Ze test? Now I find that really scary, COS IT SHOULDN`T BE ENERGISED TO START WITH!

"You started"; but I`m not sure you can finish.

Who indeed??

Hi Kme,

Point taken about the RCD x5 test, i shouldnt have realy carried out the RCD test withyou testing and checking the Zs reading, looked at some notes from college and makes sense.

When i said my meter,( Robin KTS 1620, old and second hand) triped an RCD while carring out a Ze test, i didnt say or mean this current installation im talking about, i meant my test rig at home. This meter wont carry out even a Zs without occasionaly tripping an RCD.In manual is says to disconnect RCD temperarly while carring out test.

Your constructive comment, "not sure i can finish", well that might well be true, but i didnt come out of college after 3 years and pretend to know everything there is about sparking.It actually taught me how much there is still to learn. I came on the forum to basicaly ask for a little guidance, not to be be-littled.

Heck, someone else, who is learning of course(none of us are born with all the experiance and knowledge)might learn something for the topic.

Sorry if the topic was of no interest to you.

Blimey, i dont want to fall out with anybody on these forums, but did someone poo in your cornflakes yestoday?

 

[SPECIAL LOCATION]

Hi Noz,I tested the RCD with loads connected. We was taught at college to run a RCD test with the installation engergized, either a kettle lead from meter in a socket outlet or a 2 or 3 lead instrument at a lighting rose etc, so im not with you there?

Your college taught you wrong then!

Did you never read the On Site Guide as part of revision??????

Or you just don't remember...

headbang

go and read 11.1 page 106 green OSG

or

11.1 page 91 of Red OSG...

or

11.1 page 81 of Brown OSG...

twas even page 78 in olwld Yellow un...

LOADS DISCONNECTED when testing RCD's!!!!

Test as near to the RCDs point of installation as practical...

These are in all honesty BASICS!!!!!

its not surprising you struggle with fault finding.

:C

 

[kme]

Hi Kme,

I came on the forum to basicaly ask for a little guidance, not to be be-littled.

Lee, you misunderstand. My post was intended as guidance, not to belittle you or anyone else. If someone is out of their depth for whatever reason (some people can`t get their heads around 3phase; others can struggle with some aspects of fault finding), then I think it best to point out that they may be unable to resolve the problem, due to either a lack of understanding of the procedures required, or simply a lack of experience in these types of fault.

Heck, someone else, who is learning of course(none of us are born with all the experiance and knowledge)might learn something for the topic.

Sorry if the topic was of no interest to you.

Mate - if a topic is of no interest to me, or I don`t believe I can offer anything useful - I don`t respond at all. I was attempting to provide my opinion, based on the info. you`ve provided within this thread. Maybe I shouldn`t have.

Blimey, i dont want to fall out with anybody on these forums, but did someone poo in your cornflakes yestoday?

I`m not about to "fall out" with anyone - and I don`t consider my response to be out of character with my typical responses to similar scenarios. Sorry if you didn`t like it. :C

(this thread - :coat for me)

KME

 

[lineman]

Seems quite a few people feel "belittled" after posting questions lately. Just an observation.

 

[Doc Hudson]

Seems quite a few people feel "belittled" after posting questions lately. Just an observation.

Thats good news, as it goes to show we have real human members, not robots, and the forum is still encouraging debate. Heres another observation. With over 18,000 members, over 600 persons on-line at this point in time, An experience spectrum from DIY though to 30+ year time served, 3-phase heavy industry to domestic to camping sites etc. I am not surprised that there are occasions when one member or another may find a question rather basic. As it has often been said, the written word on a forum does not display body language or tone of voice very well. Some people occasionally dislike the way they are told some thing, this is common place throughout workplaces and homes around the country. Debate and discussion typically has opposing views, (listen to the average banter in the typical pubs and clubs in the towns where you live). The forum is part of this real world and there will be differences of opinion, any person expecting everything to be all yes sir and full agreement has unrealistic expectations. However, where there are opposing opinions, it will not resort to bad language and a basic level of respect will be maintained, otherwise members will not be welcome to discuss the various topics.

Doc H.