Cable Size

[Jono Pashley]

MCS installation instructions for solar pv(MIS3002) refer to the department of trade and industry best practice guide, in the current version of the guide it states:

An inverter supplied from a PV array must preferably be installed in a

dedicated circuit in which:

no current-using equipment is connected, and

no provision is made for the connection of current-using equipment,

and

no socket-outlets are permitted.

An inverter must not be connected by means of a plug with contacts

which may be live when exposed.

Where an electrical installation includes a PV power supply system

without at least simple separation between the a.c. side and the d.c.

side, an RCD installed to provide fault protection by automatic

disconnection of supply must be type B RCD according to BS EN 60898

(IEC 60755, amendment 2).

a.c. cables are to be specified and installed in accordance with BS 7671

So in order to comply with this and BS7671s requirements it would be very hard to comply on a pre existing cable

Should be noted that the draft update to the DTI guide if it passes in its current form no longer uses the word preferably and has been changed to should.

Looked further into MIS3002 and found on page 8:

Furthermore an inverter supplied

from a PV array must be connected via a dedicated circuit, to a spare fuseway in the main

distribution unit, or to a fuseway in an additional dedicated distribution board.

 

[newman]

MCS installation instructions for solar pv(MIS3002) refer to the department of trade and industry best practice guide, in the current version of the guide it states:An inverter supplied from a PV array must preferably be installed in a

dedicated circuit in which:

no current-using equipment is connected, and

no provision is made for the connection of current-using equipment,

and

no socket-outlets are permitted.

An inverter must not be connected by means of a plug with contacts

which may be live when exposed.

Where an electrical installation includes a PV power supply system

without at least simple separation between the a.c. side and the d.c.

side, an RCD installed to provide fault protection by automatic

disconnection of supply must be type B RCD according to BS EN 60898

(IEC 60755, amendment 2).

a.c. cables are to be specified and installed in accordance with BS 7671

So in order to comply with this and BS7671s requirements it would be very hard to comply on a pre existing cable

Should be noted that the draft update to the DTI guide if it passes in its current form no longer uses the word preferably and has been changed to should.

Looked further into MIS3002 and found on page 8:

Furthermore an inverter supplied

from a PV array must be connected via a dedicated circuit, to a spare fuseway in the main

distribution unit, or to a fuseway in an additional dedicated distribution board.

Thanks for that

---------- Post Auto-Merged at 17:11 ---------- Previous post was made at 17:06 ----------

not a million miles from me,if no-one else is closer,

I do work from Widnes right up to Preston and beyond,

do some work in Ormskirk.

been known to work in London village and the Lakes or across to Geordieland and even in Andy's back yard,

done a job in Lytham not so long ago.

The instilastion guy is comeing Tues I will give him his chance,I will keep you posted, I live 5 mins from Ormskirk,Burscough,

 

[steptoe]

I live 5 mins from Ormskirk,Burscough,

I was there a few weeks back picking up an engine.

 

[Andy™]

I was there a few weeks back picking up an engine.

let me guess, its only 1 horse power, and has 4 legs?

 

[green-hornet]

not a million miles from me,if no-one else is closer,

I do work from Widnes right up to Preston and beyond,

do some work in Ormskirk.

been known to work in London village and the Lakes or across to Geordieland and even in Andy's back yard,

done a job in Lytham not so long ago.

Give me a shout Steps if you do go, would be good to meet a fellow rodder

 

[steptoe]

deffo G-H, will do,

are you going to Elex Manchester?

 

[green-hornet]

If your there I will book my ticket now

 

[steptoe]

Im going, (although it will be on the Thursday as we are off down south for a few days on the Friday morning.)

and I think we may have a visitor from the north part of Cymru too.

 

[NozSpark]

Well I do have tickets,,, if that means anything

 

[newman]

Thanks for that---------- Post Auto-Merged at 17:11 ---------- Previous post was made at 17:06 ----------

The installation guy is coming Tues I will give him his chance, I will keep you posted, I live 5 mins from Ormskirk, Burscough,

The installation guy came today, he slowly came round to the idea that to keep the peace he would consider changing the cable(only under pressure from the information gained on the forum, still reckons the inverter is set up wrong though) I have offered to half the cable cost. Putting the cable direct from the barn CU(where the panels/inverter are) to the house CU Is 70meters, could anybody tell me what size of cable I will need(don't trust him)It will be mostly clipped above ground.

 

[Manator]

I think the last calcs I did sized it at 16mm, no doubt someone will answer more definate.

 

[steptoe]

still reckons the inverter is set up wrong though

so has he changed the settings on the inverter now then?

 

[Andy™]

so has he changed the settings on the inverter now then?

to the 'bodged 6mm cable instead of 25' setting?

 

[newman]

so has he changed the settings on the inverter now then?

NO but he is desperate to try

---------- Post Auto-Merged at 20:21 ---------- Previous post was made at 20:15 ----------

For 150 meters at 16Amps 230V (but is it 150, 130 or 70 as i got confused as to the length of run!)1% VD would need 50sq mm SWA from table 4D4A on a 150 meter run

Why not ask your installer to send you their calculations for their selected cable for the length of run for your Inverter to see if they know what they are doing (you can post it here!), I very much doubt they would be able to afford to install 50sq mm cable let alone know how to connect it !

Can see your confusion, but the new length of cable will be 70 meters, would rather get the right calculations from here then I know them to be right

 

[Manator]

Just checked my calcs and now get it to 25mm giving 3% volt drop

 

[Andy™]

Can see your confusion, but the new length of cable will be 70 meters, would rather get the right calculations from here then I know them to be right

so the inverter has ben moved 80mtr?

 

[OnOff]

The installation guy came today, he slowly came round to the idea that to keep the peace he would consider changing the cable(only under pressure from the information gained on the forum, still reckons the inverter is set up wrong though) I have offered to half the cable cost. Putting the cable direct from the barn CU(where the panels/inverter are) to the house CU Is 70meters, could anybody tell me what size of cable I will need(don't trust him)It will be mostly clipped above ground.

Did I read he's with the NICEIC? Isn't part of the "deal" when you are a member with them that they guarantee your work for a period of some years as in potentially they will have it put right and boot you out of the "club"? That was the impression I got when their nice Mr Tony Cable came to our college a few years back. Bet the bloke wouldn't want you contacting them and asking their take on it! Put that to him

 

[newman]

Did I read he's with the NICEIC? Isn't part of the "deal" when you are a member with them that they guarantee your work for a period of some years as in potentially they will have it put right and boot you out of the "club"? That was the impression I got when their nice Mr Tony Cable came to our college a few years back. Bet the bloke wouldn't want you contacting them and asking their take on it! Put that to him

Unfortunately he's only with NAPIT does it still apply

 

[newman]

70 meters 16 Amps 230 Volts Cable Multicore armoured 70deg C Thermoplastic Table 4D4A1% volt drop (2.3volts at 230 V) Cable = 25sq mm VD = 1.96 Volts

2% volt drop (4.6volts at 230 V) Cable = 16sq mm VD = 3.14 Volts

3% volt drop (6.9volts at 230 V) Cable = 10sq mm VD = 4.93 Volts

6sq mm would give a VD of 8.18 Volts

Based on your run i would be installing a 1% VD cable for your system

Page 26 here recommends a 1% figure but this is only a guide, although good practise for installations with long runs and any voltage problems

Thats GREAT, thanks for your help...........

 

[newman]

[quote name='Andy