Cable Size

[steptoe]

There's no E in Scotch Whisky.Other, inferior, alcoholic drinks might spell it with an E in there somewhere.

dont you start that,!

good job there is no P in whiskey, isn't it? :slap

 

[kerching]

dont you start that,!good job there is no P in whiskey, isn't it? :slap

Give it a few hours and it will all turn to P....................... :run

 

[professional]

.... then it can be exported to Canada for their whisky market ....

 

[newman]

Had a responce from the DNO today in the form of an email

More

5 o

Electricity North West Limited

PO Box 4375

Manchester

Date 14 May 2012

Voltage Variations

I refer to your recent enquiry regarding the quality of your electricity supply. My investigations have revealed that the voltage recorder results for your property show a reasonable voltage that is within statutory limits.

The voltage average is below 253v and rises above this upper limit only twice for a fraction of a second. This does not warrant any works to remedy.

In view of the results obtained, we do not propose to take any further action.

However, if you are still experiencing problems with your supply, then I recommend that your installation should be inspected by an electrical contractor in case the problem is on your own installation.

May I thank you for your assistance in this matter.

Yours sincerely

 

[steptoe]

Lytham?

or that general direction IIRC

 

[newman]

Its not the Grid ImpedanceIts not the DNO's Supply

Its the badly designed install

The installer was a Muppet and quite possibly still is a muppet

I suggest you get someone properly qualified and experienced in PV to give you a report for you to take this further and get it sorted at the installers expense

Including a formal written complaint to Napit and REAL

---------- Post Auto-Merged at 19:45 ---------- Previous post was made at 19:45 ----------

Where did you say your were again ?

I am half way between Liverpool and Preston

The installer is comming tomorrow

---------- Post Auto-Merged at 20:06 ---------- Previous post was made at 20:05 ----------

Burscough

 

[steptoe]

correct. you are right, that is where you live,

 

[newman]

correct. you are right, that is where you live,

Good........... I was getting worried

 

[ProDave]

"average below 253V" is still a bit vague though isn't it?

It's supposed to be 230V + 10% / - 5%

so the maximum allowed is 253V

So just saying the average is below the limit doesn't tell us a lot. The measured average could be 252V and that statement would still be true.

While I agree the installation is at fault, the DNO are not actually helping prove or disprove what, if any, effect the supply impedance may be having on this particular problem.

 

[ivor dispatch]

@NewmanWhen you spoke to Napit did you get the name of whoever you spoke to who stated the install was ok with the PV going into a sub board

Can you refresh my memory of the conversation you had and ideally who you spoke with

@ Newmen is there RCDs on the sub board that will/can be influenced by the inverter

 

[professional]

Or is the sub-board itself fed by an RCD closer to the service head?

What I can`t understand is that I`ve spoken to NAPIT and was told that the install that you describe in NOT OK.

So, either your description of the install is inaccurate/incorrect or something does NOT add up here.

I think that it would be logical to test the rcd trip time on any potentially affected circuit both with the PV connected and with it isolated to compare the results .... until such a comparison is done, we can only surmise as to any possible detriment to the the existing install.

Of course, any competent person would carry out such a procedure as part of their duty of care under the EAWR as recommended by BS7671 - but do the PV installers? ]

 

[ivor dispatch]

"average below 253V" is still a bit vague though isn't it?It's supposed to be 230V + 10% / - 5%

so the maximum allowed is 253V

So just saying the average is below the limit doesn't tell us a lot. The measured average could be 252V and that statement would still be true.

While I agree the installation is at fault, the DNO are not actually helping prove or disprove what, if any, effect the supply impedance may be having on this particular problem.

@ProDave , I would say the inverter is a distance from the point, the DNO attached the voltage recorder ,

I am surprised they got a reading of 253V at that point.

I know some think the SMA chart is a load of tosh,,, if you measure the voltage at the incomer(meter point inverter off), then measure the grid/circuit impedance at the point of connection to the inverter,,, the chart/graph will show the possible voltage rise at the inverter.

 

[steptoe]

@NewmanWhen you spoke to Napit did you get the name of whoever you spoke to who stated the install was ok with the PV going into a sub board

Can you refresh my memory of the conversation you had and ideally who you spoke with

I think Neal Cumberland (?) covers round this area anyway.

 

[ivor dispatch]

The DNO would have measured at the service head, that's where there responsibility endsCan you tell us how you would measure the grid impedance ?

using your earth fault loop impedance meter connect L to L then N to N set L N on display press test button,,, if you have a three wire meter conect the earth to N and L toL and N to N press the test button

I am sure you know how but might not know why.

 

[steptoe]

Whos Neal?

I dunno :C

is it Neil ? I did put a (?) for that very reason, well he rang me today, so he must do somewhere round here anyway.

 

[newman]

@NewmanWhen you spoke to Napit did you get the name of whoever you spoke to who stated the install was ok with the PV going into a sub board

Can you refresh my memory of the conversation you had and ideally who you spoke with

Heres some of the emails

thanks for your email

Unfortunately I don't understand ( as I am not an electrician)

What I want to know,is given the potential load on the cable ( given in the email on 21st April) Of about 70amps+3amps for the farm shop ,was the installer correct in fitting the PV system on my existing cable .This is what I mean ,is the cable safe.

Also I need you to confirm that the cable ,given all the information supplied in my emails complies with ALL the relevant regulations.

The installation of the PV circuit into a new consumer unit is correct ,but it replaced the original one ,and so I only have one CU in the barn for sockets, lights and PV

The inverter/SWA feeds sockets/lights DOWNSTREAM of any rcd protection then how can the installation meet the requirement for supplementary protection for socket outlets.

Also The inverter circuit is a distribution circuit so according to the BS7671 it should not be fitted on the load side of ANY protective device feeding other final circuits.

Please comment

NAPITs reply was

In response to your first email and the one below I can confirm that based on the information you have supplied and given that the size of the cable is correct for compliance with the requirements for volt drop as per BS7671 2008 Amendment 1 2011 the design appears to be compliant.

The PV circuit is not classed as a distribution circuit, it is classed as a final circuit supplying a fixed piece of equipment. In addition this circuit being on the same circuit supplying sockets outlets provided with RCD protection for supplementary protection will, in the event of the RCD tripping cause the inverter to trip out thus isolating the socket outlets and any equipment connected to them.

Please note that NAPIT Complaints is only here to deal with complaints made against its members and it is not a technical helpline for customers of our members. Whilst I have been happy to answer your questions up to now I cannot continue to do so to the detriment of the cases I am currently dealing with. If you have any further questions relating to your installation then I would ask you to deal directly with the installer as the supplier of your PV system who can seek confirmation through his access to the NAPIT Technical helpline.

Regards,

Mark Nelson

Complaints Manager

 

[steptoe]

OK, from what I understand in that email he is saying the circuit meets the requirements of 7671 as a normal circuit,

my viewpoint, he does not understand the additional requirements of PV circuits.

I also think he is getting nervous and wants to speak to the installer before you go public on this and make Napit (along with all the others) out to be the scam they are.

 

[newman]

@ Newmen is there RCDs on the sub board that will/can be influenced by the inverter

There is an RDC on the CU in the shop which the electric goes through and there is a RCD on the barn CU where the panels/inverter is

 

[professional]

Has the installer provided an EIC for the PV install as this will include details of any rcd trip times measured whilst the PV is connected downstream of the RCD?

 

[ivor dispatch]

I don't know a lot I must admit and every day is a learning curve for me....So is there a difference between your term of "grid impedance" and what a loop test result gives you?

You must enlighten me as to why I would not know why ?

No" earth" just grid/circuit L N impedance

But you knew that