6mm cable or 4mm ?

[Ambilkate]

What cable do you use 6mm or 4 mm does it matter when only doing a 6 to 8 meter run ?we are looking at putting 1x240 solar on van now but can't buy 6mm over the counter only 4mm we can purchase 6mm of ebay but trying to source all items locally and can only get 4 mm may have to give up and buy of eBay have all the links via funsters Thankyou but Kate doesn't like to buy over the net and trying to sorce everything today
Bill

 

[scotjimland]

Hi Bill

yes.. it does matter ..in a low voltage application, the cable size is critical, not for the load.. but for the losses.

the cable size is determined by the the length of run, wattage, and acceptable loss ..

using the cable sizing tool, the theoretical correct size for that panel for a 6 - 8mt run, allowing for 3% loss, is 10mm

4mm is too small.. and 6mm will just about do it.. the smaller the cable size the greater the volt drop = the less efficient your panel..

 

[Gorse Hill]

Depending on what you calcs are
Screw fix do 10mm t&e and if using flex 6mm has a similar current carrying capacity , pretty sure B&Q do as well
I would personally put in place the largest conductor allowing for further expansion
Whats required and the cost involved on that length is minimal

 

[Gromett]

I always recommend 6mm cable no matter how long the run or how little wattage you are putting on. It also reduces losses. In addition if you want to add additional panels in the future you won't need to upgrade the wiring.

The cost difference between 4 and 6mm cable is negligible compared to the overall cost.

I buy my 6, 16 and 25mm cable on ebay and it is very cost effective.

Auto electricians will have the cables in stock but will be expensive.

 

[Freespirit1]

Hi Bill - just google "Industrial control Panel Manufacturers" in your area - one of those will have the right cable and colour you need - they will even crimp the correct lugs on for you too I expect while you wait.

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[Gromett]

PS: Remember when using calculators that the voltage at the solar panel side is higher so the current is lower. My panels from memory are about 17V I think. So 240W / 17V = 14Amps.

 

[Theonlysue]

I don't think that their regulator will allow over 300w re panels.

 

[scotjimland]

PS: Remember when using calculators that the voltage at the solar panel side is higher so the current is lower. My panels from memory are about 17V I think. So 240W / 17V = 14Amps.

that was the numbers I used

 

[Ambilkate]

Bills measuring up on the roof at the minute this is what is on the back of the panel we saw yesterday

 

[Gromett]

that was the numbers I used

Sorry my comment wasn't aimed at you but anyone who doesn't understand electrics. I have seen people putting 12V into the calculator and wondering why they have to use 10mm cable where others have only used 6mm.. I knew you would know what you were doing on this

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[Gromett]

Bills measuring up on the roof at the minute this is what is on the back of the panel we saw yesterday View attachment 79364

That looks like a 48V panel. Make sure your regulator handles 48V in and 12V out. (I am sure you have already)
AT 52V you would only need 1.5mm cable for 3% losses according to Jim's calculator and 4mm would give you 1% losses. I would still go for the 6mm cable however. Also please check the cable you use is rated at 50V+.

 

[Gromett]

The cable I use is this Broken Link Removed
It is rated at 600V AC so can handle 50V DC no problems.
10 Meters is £12 inc carriage.

 

[laird of Dunstan]

Those cable calculators are very helpful , I'd work out the run and have the cables cut to size ,don't use anything that will chew up the end of the cable when cutting, if you buy the lugs online make sure that they are the crimping type ,pop into your local control panel shop ,ask for the workshop and they guys will most likely crimp the ends for you ,its important that the correct tool is use to crimp as it will stamp a number at the same time as the crimp ,ask the guys in the panel shop to put on some heat shrink at the ends.
I've built the odd control panel in my time ,it's best to use multi strand cable rated to the correct voltage, twin and earth is solid copper and is not suitable for your application

 

[Ambilkate]

Thanks everyone back to the drawing board

 

[Freespirit1]

I've built the odd control panel in my time ,it's best to use multi strand cable rated to the correct voltage, twin and earth is solid copper and is not suitable for your application

Snap - all good advice there - and memories of Brand Rex Tri rated eh!

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[laird of Dunstan]

Snap - all good advice there - and memories of Brand Rex Tri rated eh!

I started off as an apprentice electrical fitter on flameproof, explosion proof ,HV and LV switchgear , I've built untold numbers of control panels
oh yes we know what tri rated cable looks like

 

[Judge Mental]

I started off as an apprentice electrical fitter on flameproof, explosion proof ,HV and LV switchgear , I've built untold numbers of control panels
oh yes we know what tri rated cable looks like

and I have installed them in another life

 

[laird of Dunstan]

and I have installed them in another life

"Laughing" I'm looking at one right now with an old satchwell bms system ,been there to judge ,built them,installed them ,tested them ,commissioned the poxy things

 

[Judge Mental]

"Laughing" I'm looking at one right now with an old satchwell bms system ,been there to judge ,built them,installed them ,tested them ,commissioned the poxy things

I remember now!....your ones were Rubbish!lol Still have nightmares regards wrestling with monster armoured cables

 

[laird of Dunstan]

I remember now!....your ones were Rubbish!lol Still have nightmares regards wrestling with monster armoured cables

Oh yes bodgit and scarper control panels

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[Freespirit1]

I started off as an apprentice electrical fitter on flameproof, explosion proof ,HV and LV switchgear , I've built untold numbers of control panels
oh yes we know what tri rated cable looks like

Wow - me too (well a few) - small world eh! and I've built some in nuclear subs, and a few nuclear power stations (tongue in cheek) - one was in Russia (Chernobyl if I remember rightly) - mind you we ran out of the tri rated at one point and had to use a bit of twin and earth I found in the back of the van - it seemed to do the job ok?

 

[JeanLuc]

If that panel is indeed a 48V model it will not work with the LR1218 regulator which is suitable for panels with a maximum off-load voltage of 25V.

The label you showed states an open circuit voltage of 52.4 volts!

 

[Ambilkate]

If that panel is indeed a 48V model it will not work with the LR1218 regulator which is suitable for panels with a maximum off-load voltage of 25V.

The label you showed states an open circuit voltage of 52.4 volts!

Thanks Philip
regards Kate x

 

[DBK]

You will need something like the Victron BlueSolar MPPT 100/30 controller. This can take both the voltage and current of your panel. The make is the only one @eddievanbitz recommends.