Another Pair of Eyes would be appreciated

[securespark]

I must say I have it on good authority from several manufacturers (MK, Hager & Eaton) that their RCD's should be tested in isolation, not from a final circuit.

 

[oharaf]

Thanks Fellas, been putting the children to bed so been away for a while

So let me try and tidy a few areas up

1. The "Zs at this board" I think this should really be "Ze at this board"

2. Any way I measured Ze as 0.23 ohms, TN-S system so this is fine


3. The "Utility Room" is actually the office and as full of IT equipment
(and the boiler) don't want any nuisance tripping so have not put it on
RCD

(Oh by the way this is a 16th Ed install from back in Feb/March)


4. Way 8 - Up Stairs sockets I agree r2 seems a little high and will check
all these in the morning.

5. The RCD results; I tested the RCD on each final at the point where I
identified highest R1 + R2 - this was how I was taught btw!!

The 1 x In are all below 200ms and the 5 x In are all below 40ms so
these are all good!!

Just for info tested in this order 10,11,9,8 well spotted!!!


Oh thanks for the Max permitted Zs, I looked these up in new OSG page 103 table 2D, I read all the garb before on page 99 which says use this table, low and behold B6 = 6.18 and B32 = 1.16!!!

Anymore comments much appreciated

 

[GaryMo]

1. The "Zs at this board" I think this should really be "Ze at this board"

2. Any way I measured Ze as 0.23 ohms, TN-S system so this is fine

Where did the entered 1.29ohms come from?

5. The RCD results; I tested the RCD on each final at the point where I
identified highest R1 + R2 - this was how I was taught btw!!

The 1 x In are all below 200ms and the 5 x In are all below 40ms so
these are all good!!

Just in case your assessor asks, what's the maximum RCD trip time at 1x rated current for a BS EN 61008 RCD? BTW, It's not 200ms

Oh thanks for the Max permitted Zs, I looked these up in new OSG page 103 table 2D, I read all the garb before on page 99 which says use this table, low and behold B6 = 6.18 and B32 = 1.16!!!

I'm led to believe it's the maximum permitted values (from BS7671) that are entered and the measured value is checked against 80% of that figure if the circuit isn't at its operating temperature under load.
It's certainly the opinion of the ECA anyway. Ask your assessor for his view.

Good luck, hope all goes well.

 

[FingRinal]

I'm led to believe it's the maximum permitted values (from BS7671) that are entered and the measured value is checked against 80% of that figure if the circuit isn't at its operating temperature under load.
It's certainly the opinion of the ECA anyway. Ask your assessor for his view.

The reason I don't like doing it like that is that I think it's preferable to enter the 'corrected' maximum figure for comparison as it speeds up re-verification when I double check everything. Once you've entered the OSG figures a few times, you memorize them and you know instantly whether a test is OK. But I suppose it doesn't really matter. The important thing is that the test results need to be compared with 'corrected' design values.

 

[GaryMo]

The reason I don't like doing it like that is that I think it's preferable to enter the 'corrected' maximum figure for comparison as it speeds up re-verification when I double check everything. Once you've entered the OSG figures a few times, you memorize them and you know instantly whether a test is OK. But I suppose it doesn't really matter. The important thing is that the test results need to be compared with 'corrected' design values.

I agree with you!
However, I was corrected in a thread on here when I mentioned I entered 80% values so chose to contact the technical department at the ECA for clarification. They also said I should be entering 100% values

In fact, it was this thread if you're interested //www.diynot.com/forums/viewtopic.php?p=940815#940815

 

[oharaf]

Hi Gary, there is a distinct wiff of pap in our house, will last until Friday tea time

Anyway 1.29 came from my scriiblings!!!

Ze = 0.23 and highest R1+R2 = 1.06 so add these and you get 1.29 approx Zs!?!?!?!

Correct me if I'm wrong but Maximum trip time for 61008 is 300ms? at 1x

 

[GaryMo]

Correct me if I'm wrong but Maximum trip time for 61008 is 300ms? at 1x

Sure is though was drawn to mention is by this:

5. The RCD results; I tested the RCD on each final at the point where I
identified highest R1 + R2 - this was how I was taught btw!!

The 1 x In are all below 200ms and the 5 x In are all below 40ms so
these are all good!!

I'm sure you'll be fine

 

[oharaf]

Sorry at college they harped on so much about 200 and 40 that it sticks in your mind, still high standards hey!!!!!

Thanks for your help, oh and the excellent MFT1502/2

 

[GaryMo]

Sorry at college they harped on so much about 200 and 40 that it sticks in your mind, still high standards hey!!!!!

I know what you mean. 1x = 40ms, 5x (5x40) = 200ms. It kind of makes sense!

Thanks for your help, oh and the excellent MFT1502/2

No problem at all

 

[Spark123]

Hi Gary, there is a distinct wiff of pap in our house, will last until Friday tea time

Anyway 1.29 came from my scriiblings!!!

Ze = 0.23 and highest R1+R2 = 1.06 so add these and you get 1.29 approx Zs!?!?!?!

Correct me if I'm wrong but Maximum trip time for 61008 is 300ms? at 1x

For Ze (impedance external to the installation) you need to enter 0.23 in the Ze box on the certificate
This Ze is added to each of the (R1+R2) values in turn to ensure that the Zs is low enough for each circuit before energizing the circuit.
As a rule of thumb, the Zs should not exceed 3/4 of the maximum permissable values i.e. 3/4 of those given in BS7671.
Personally, for the max permissable efli figures on the certificate I'd enter those from chapter 41 of the regs as you are not guarenteed to be in the correct temperature range whilst testing to ensure any other figure is accurate.
The max time for a BSEN61008 is 300ms. The old BS 4293 standard devices have to trip within 200mS. The device should be measured in isolation so you are not getting misleading figures caused by anything plugged in, capatitance etc.

 

[BS3036]

I'd be interested to know something about the form itself. Is it software produced? Is it specific to NAPIT?

 

[oharaf]

Hi BS, the form is from a 'package' that I was given by I fellow student at college.

I believe it is based on an NICEIC form, there are a whole host of them covering all possibilities.

What are your opinions on it, I find the spacing a bit tight but otherwise it produces a nice neat readable form

 

[BS3036]

What I found interesting, only ever having seen the BS7671 form, was the column(s) for max values permitted. It's interesting because Joe Bloggs could look at a BS7671 form and not know how close a circuit was from not passing.

 

[oharaf]

To be honest joe Bloggs looks at these forms and it melts his ear wax.

A friend of mine (scientist type bald head glasses 2degrees and a masters) looked at one of these forms when I had completed it and told me it was

"Typical maths bo11ocks, cooked up to make everyone else look stupid"

I knew he was jealous of my maths degree

But this is the man who strips T&E with his teeth!!!!

I always go through the results with my customers and try to explain the readings if they ask

(except on Holmewood Estate where breathing unaided is a sport!!)