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Topic Title: niciec domestic electrical installation test cert??????
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Created On: 25 July 2005 08:22 PM
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 25 July 2005 08:22 PM
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ramrod

Posts: 135
Joined: 05 July 2005

on page 3 (circuit details) of the test cert what should i enter in "designation of consumer unit" ?

is 1decimal place for readings acceptable?

im making a cert out for a shower in a domestic property, testing of the rcd at its rating is listed in the 1st column, in the second at 51?n do i test at 51ma & note the trip time?
 25 July 2005 08:44 PM
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SpaElectrical

Posts: 1479
Joined: 16 December 2003

I'd try the NIC Helpline mate.
They make up their own rules, so I'm bound to get it wrong if I advised you further.
I'd recommend the NIC's Inspection & Testing book. This tells you how to fill out their forms.
You should know how to test RCDs mate - its fundamental knowledge.

If the RCD is a 30ma one, then it should trip within 40 miliseconds at 5 times its rated tripping current, which is 150ma.
You should test it at 1/2 its rated current and it's rated current.

All of the above tests should be carried out twice
Once at 0' phase angle and once at 180' phase angle.
You should then carry out a functional test by pressing the 'test' button.

Hope this helps - don't tell the NIC I told you!




-------------------------
"Let the evidence guide the research. Do not have a preconceived agenda which will only distort the result."
 25 July 2005 08:45 PM
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John Peckham

Posts: 7401
Joined: 23 April 2005

I assume you are not yet an NICEIC member as you would not be asking these questions? NICEIC haters need not comment on this point.

For one consumer unit it is usual to put DB1.

It is usual to put 2 places of decimals for resistance, Ze and Zs readings.

In the schedule of circuit details you would put the I delta N rating of the RCD in mS e.g 30.

In the schedule of test results you put the measured figure for the highest time (0 degrees or 180 degrees) at 1 x I delta N in mS e.g 76. In the second column you put the highest figure for 5 X I delta N ( 0 degree or 180 degrees) in mS e.g 24.

Does this help?

Regards

John Peckham

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 25 July 2005 09:14 PM
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LONESOME

Posts: 238
Joined: 27 May 2002

quote:

Originally posted by: johnpeckham
I assume you are not yet an NICEIC member as you would not be asking these questions? NICEIC haters need not comment on this point.

For one consumer unit it is usual to put DB1.

It is usual to put 2 places of decimals for resistance, Ze and Zs readings.

In the schedule of circuit details you would put the I delta N rating of the RCD in mS e.g 30.
^
TYPO........mA
 25 July 2005 09:46 PM
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John Peckham

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Well spotted 30mA.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 25 July 2005 09:58 PM
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ramrod

Posts: 135
Joined: 05 July 2005

quote:

Originally posted by: johnpeckham
I assume you are not yet an NICEIC member as you would not be asking these questions? NICEIC haters need not comment on this point.

For one consumer unit it is usual to put DB1.

It is usual to put 2 places of decimals for resistance, Ze and Zs readings.

In the schedule of circuit details you would put the I delta N rating of the RCD in mS e.g 30.

In the schedule of test results you put the measured figure for the highest time (0 degrees or 180 degrees) at 1 x I delta N in mS e.g 76. In the second column you put the highest figure for 5 X I delta N ( 0 degree or 180 degrees) in mS e.g 24.

Does this help?

Regards

John Peckham


yeh thanks... should have known this...wish id done my 2391 now!!
 28 October 2008 05:58 PM
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Tezz

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Joined: 28 October 2008

I have a distribution board with some breakers protected by an RCD. From the protected breakers I have a power ring main and a lighting ring main both protected by their breakers. I tried connecting a low energy 2D light to a lighting breaker on the unprotected side of the distribution board and this kept bring out the RCD, resulting in moving it to the Protected side of the board, any answers why the RCD kept tripping???
 28 October 2008 06:02 PM
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OMS

Posts: 19539
Joined: 23 March 2004

power ring main and a lighting ring main


Are you sure about the lighting "ring main" ?

any answers why the RCD kept tripping?


Probably a mix up in where you connected the Neutral

Regards

OMS

-------------------------
Failure is always an option

Edited: 28 October 2008 at 06:03 PM by OMS
 28 October 2008 06:05 PM
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perspicacious

Posts: 7183
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Welcome Tezz

"a lighting ring main"

Odd design

"resulting in moving it to the Protected side of the board"

Didn't the electrician who did this offer any advice?

Regards

BOD
 28 October 2008 06:32 PM
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Testit

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Actually you can call it what you like.. designation is simply what you are labelling it as.. you can call it "led zep 1" if you like, providing it is labelled "led zep 1".. for me I always us CU1, CU2 etc for consumer units in domestics.. CU being abreviation for whatever you imagine it to be...

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 28 October 2008 06:47 PM
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sparkingchip

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Last friday i took out a wylex rewirable board in a Bungalow.

I pulled the Fuses and thought they looked brand new, not one fuse had blown in thirty years, not a mark on them.

I found out why, the Socket Ring had a 30 amp fuse on each end and the lighting was laid out as a ring with a 5 amp fuse on both ends.

The Socket ring gave a low end to end reading, this turned out to be because he installed a short ring then connected the old rubber radials into it to advoid pulling cables under the floor.

I was told the previous owners son had rewired the Bungalow rather than pay an Electrician.

I seem to spend my life sorting out potential and actual problems, so to go back to the question raised by Tezz, I go with OMS comments check the Lights are actually a ring and what fuses/ mcb's they are connected to and if it is a ring make it into one or more radials, then check for seperation of circuits and weather there are any "borrowed neutrals" in place if so remove, also insultion test for faults.

If all fails you may have to combine them into one circuit to be safe.

Andy Betteridge
 28 October 2008 07:08 PM
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OMS

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I found out why, the Socket Ring had a 30 amp fuse on each end and the lighting was laid out as a ring with a 5 amp fuse on both ends.


A tad unexpected in your average domestic although we used to use a very similar approach for 630A/1000A distributors around several sites that require some fairly robust power supplies - each end being fed from different switch board sections and possibly off different transformers - bit of a grind working out the fault levels I can confirm

Regards

OMS

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Failure is always an option
 28 October 2008 10:41 PM
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ebee

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"A tad unexpected in your average domestic"

Frayed Knot.

Seen it a few times so be carefull out there people.

One "Old Chestnut" is two rings - lets call `em A & B

Ring A leg 1 & Ring B leg 1 MCB1 and Ring A Leg 2 & Ring B leg 2 on MCB2.

So two "Rings" commoned with OPD of 60 Amps each 60 Amps total (64 & 64 in new money).

And yes lighting circuits "ringed" either by design or accident. By design usually ringed and one MCB serving it so all other things being equal no great problems but others where two MCBs connected as if two radials accidententally joined.

The mind bogles.

Johns mA/mS slip was a "deliberate accident" (He is a tutor you know!) it`s his way of keeeping a check on us - The great Unwashed

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Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 29 October 2008 08:19 AM
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Jaymack

Posts: 4617
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Originally posted by: ebee
Johns mA/mS slip was a "deliberate accident"

SI is s for time in seconds - i.e. ms for milliseconds - get it right

Regards
Statistics

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