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Hi Everyone

I have had a Victron System installed in my home and while everything works as supposed, for some or other reason the DC cabling that runs from my MPPT to the Batt is getting extrmemly hot - as in it will burn your fingers if you touch it? I asked my installer if this is normal as I was seeing marks where the cable was touching the trunking and it was starting to melt the trunking where it resided on it - his reply was no, but that he cant work it out as the cable is rated to carry so many amps and that the input on that cable in amps from the MPPT gets nowhere near that.

I am based in Port Alfred and they are based in Port Elizabeth, and now with the lockdown they cant come out to see to this problem - if it is a problem? But surely a cable only gets that hot when its carrying above its rated capacity? We live in a predominantly wooden home - 60/40 split (wood/concrete,brick) but still I am concerned that this is a fire risk? This system has run for over 40 days now and no fire yet, so while I might be a little paranoid, Id rather just get some information from the likes of the folks here who know these setups really well. The heat is also only felt on the live wire coming from the MPPT (red wire) - but you can also feel the heat coming out of the junction box that houses the 100amp fuses and isolator switches for the batteries. I can provide photos and more information if needed.

Total System consists of following:

Quattro 8000kva, MPPT 250/100, Colour Control, 7kwh Pylontech (2 x US3000), 16 * 340w Peimar panels

Would appreciate any feedback so that I can take it up with the installers.

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42 minutes ago, JasonPrince said:

I asked my installer if this is normal as I was seeing marks where the cable was touching the trunking and it was starting to melt the trunking where it resided on it - his reply was no, but that he cant work it out as the cable is rated to carry so many amps and that the input on that cable in amps from the MPPT gets nowhere near that.

This is not normal at all. You have a 250/100 MPPT, with 5440whp on the roof, so in perfect conditions, losses ignored, you can expect 5440/53 = 102 amps, but the MPPT will clip the top off and allow 100 Amps. To handle that you would need 35mm square cable at least. Anything less than that will overheat. 

Made the mistake myself to install 25mm in on those MPPTs because the software tells me the cable can handle that, but in practice its not working like that. In one situation, i installed 25mm on a 250/100 and it was running at 89 degree C, changed it to 35mm and the temp dropped to 57 degree C.   

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3 hours ago, JasonPrince said:

If I am not mistaken that is 25mm that is running into the MPPT battery connector?

Going trough halve of a compression gland, that is max 16mm in my opinion (I suspect less). A 25mm cable will basically fill up the hole of the compression gland, the 35mm will go through very tightly. 

That cables are way too thin. The PV looks like 10mm and at full production, they should create  a bit of heat themselves as well. 

3 hours ago, JasonPrince said:

see how the neutral has heated and melted the housing.

 

That might point to a loose connection as well, but the cable might be contributing. 

EDIT: Just went and checked in my Vehicle. Blue Welding cable is 25mm, look as the difference between the 25mm cable (Blue) and the other cables. I am afraid, you stand a serious risk of fire, they need to sort this out soon.. 

If you want to be safe and the combiner box has fuses per string, pull the fuse on at least 2 strings. 

Edited by Jaco de Jongh
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3 hours ago, Jaco de Jongh said:

Going trough halve of a compression gland, that is max 16mm in my opinion (I suspect less). A 25mm cable will basically fill up the hole of the compression gland, the 35mm will go through very tightly. 

That cables are way too thin. The PV looks like 10mm and at full production, they should create  a bit of heat themselves as well. 

That might point to a loose connection as well, but the cable might be contributing. 

Hi Jaco. Thanks for the reply and information. Initially there was a loose connection on the live and it burnt out the bottom of the isolator. Luckily we smelt it and turned the PV array isolator off. They then came to correct the loose connection and replaced cables and burnt isolator but have run the same cables again. It was only after this that I started paying attention to the heat being generated in the cable and reported this to them. They came once to inspect after I told them about the heat generating in the cables and they said that maybe there was too much congestion in the trunking and that's why the cables were generating heat. When I called and said that that's impossible, the installer mentioned contacting someone from Victron to confirm cable sizing - then we locked down. Am I in present danger running this system as it is currently - in other words can it start fires? Sorry for the noob questions but I am no electrician.

@Jaco de Jongh is 10mm/16mm adequate for the PV array? They do get warm to the touch but nowhere near in comparison to the battery cables.

Also is it normal for your MPPT to get quite warm during high production times?

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11 minutes ago, JasonPrince said:

10mm adequate for the PV array?

4 strings, I would have run 4 mm per string and then after combining the 4 I would have used 16mm (4 x 4) 

 

11 minutes ago, JasonPrince said:

Am I in present danger running this system as it is currently - in other words can it start fires?

Definitely yes, that is why a mentioned, if you can disconnect at least 2 of the strings until they can fix the issue , you would minimize the risk.

11 minutes ago, JasonPrince said:

When I called and said that that's impossible, the installer mentioned contacting someone from Victron to confirm cable sizing -

Please tell your installer, he does not need confirmation from Victron, the SANS regulations tells you how much current is allowed for each cable size and for 16mm it is 60 Amps, 25mm = 80 amps and 35mm 100 amps, (Rule of thumb and depending on installation method). He is trying to do almost double that. 

EDIT: I have PM'd you my Cell number, You and your supplier is more than welcome to phone me. 

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2 hours ago, Jaco de Jongh said:

EDIT: Just went and checked in my Vehicle. Blue Welding cable is 25mm, look as the difference between the 25mm cable (Blue) and the other cables. I am afraid, you stand a serious risk of fire, they need to sort this out soon.. 

If you want to be safe and the combiner box has fuses per string, pull the fuse on at least 2 strings. 

Hi Jaco. Just saw this now after our telephonic conversation - what is the combiner box? I know there is a box that houses fuses in it but those as far as I understand are the battery fuses and there is only one set - in other words all the strings are combined if I understand you correctly? See the image attached where I have circled the unit - is that the combiner box? If so that only has the one fuse in it, and if I pull that out it eliminates use of the batterys. Easiest option here for me is to just turn off the PV array isolator till I can get this sorted out it seems.

20200404_201332.jpg

Edited by JasonPrince
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Just now, VisN said:

Jason,

Surely this should be classified as an emergency and warrants immediate attention despite the lock-down. I had a dangerous situation at home and managed to get an electrician out. Neither @Jaco de Jongh nor @Soltaro are trying to be alarmist, just brutally honest.

Good luck.

 

Hi Visn

I get as much and appreciate the earnest response I get from everyone here. I am trying to get in touch with an electrician who I use here at home, and trust. Having him on site will put me far more at ease with this situation, but still comes down to the fact that you trust reputable companies to install correctly and not leave you in the predicament I am currently in. Pretty disappointed to be honest. Makes me wonder (not being as informed as the rest of you here are) if this is the only fault I will find in this installation. One can only hope.

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36 minutes ago, JasonPrince said:

Hi Jaco. Just saw this now after our telephonic conversation - what is the combiner box?

I dont see a combiner box on your wall, it does seem like there is some kind of isolator, might be the PV isolator i see. the one you pointed out is the battery fuses. 

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1 hour ago, Soltaro said:

Feel free to PM me, I know the main Victron distributor and technical centre.

Who Are they, I did not know there is a main supplier in SA... 

 

 

1 hour ago, Soltaro said:

Run minimum dual 25mm DC UV Shielded to your DC combiner box or use and adapter that will accommodate 2 x 25mm cable combined and run those cables into your inverters, that would give you 50mm² per terminal into your MPPT 

Why?? What current are you expecting from combiner boks to MPPT? With 4 strings that would be less than 50 Amps..

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1 minute ago, Jaco de Jongh said:

I dont see a combiner box on your wall, it does seem like there is some kind of isolator, might be the PV isolator i see. the one you pointed out is the battery fuses. 

There is a breaker inside that particular box as well. I will take an image of it and post it tomorrow. I will also post the quote they sent me and ask you gentleman to have a look through that and see if everything that has been quoted on, paid for, has actually been installed. 

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4 minutes ago, JasonPrince said:

There is a breaker inside that particular box as well.

At the bottom right of the MPPT, you will see a little black wire in a green Connector, pull that connector out and the MPPT, will not produce any power till you push it back. That should also safeguard your system for now. I am also worried about the power cable into the inverter.  Seems like a 4 core surfix, I just hope its 6mm 4 core... 

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This is what I was quoted on and paid for. Somehow now that I have scrutinised it somewhat after all this and the comments made above, it just does not seem to add up.

Queries already would be the fuse 250amp vs installed 100amp. Solar combiner for 5kva not sure where that is. 5kva DC protection box - I would think is the box I have highlighted in previous images.

Screenshot_20200404-205736_Adobe Acrobat.jpg

Screenshot_20200404-205831_Adobe Acrobat.jpg

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5 hours ago, Jaco de Jongh said:

Going trough halve of a compression gland, that is max 16mm in my opinion (I suspect less).

yeah that looks like 10mm^2. That's underrated. Even 16mm^2 would be too thin. 25mm^2 would be bare minimum, and 35 is definitely advised.

2 hours ago, Jaco de Jongh said:

will not produce any power till you push it back

Better idea. Load VictronConnect, and set the maximum limit of the solar charger(s) to 50A. Then you can at least utilise some of the power until the cables can be replaced.

Disclaimer: Did not read the whole thread. Shooting from the hip.

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@JasonPrince 2 guys here @Jaco de Jongh and @plonkster, they the guys that will give you rite info and help you. Other thing i spotted and they can check it to, that looks like 25mm2 cable that's going in to the inverter, i compared it to the pylontech size in the cabinet. For a 8kw inverter you need to go a bit bigger then that. 

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14 hours ago, JasonPrince said:

If I am not mistaken that is 25mm that is running into the MPPT battery connector? See attached image where wiring connects to isolator - see how the neutral has heated and melted the housing.

20200404_174322.jpg

Can you maybe take a wider foto of this combiner box Please? Something is telling me they just connext the mppt battery out direct to the battery fuce breaker. 

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2 hours ago, Soltaro said:

definitely report this to Victron. 

If it's an approved reseller of some sort, definitely take it up with the local South African representatives, either Gerrit Tromp up North, or Andre du Randt down in the South.

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Also, that Hager breaker to the left of the 100A fuse holder, what is that for? Cause either that's an AC breaker used for DC.... or they have AC wiring in the same box/trunking as DC, which is also not allowed.

My goodness, this is an example of how not to do things. This is an installer that knows enough to bootlace crimp the cables for neatness... but not enough beyond that.

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18 minutes ago, plonkster said:

Also, that Hager breaker to the left of the 100A fuse holder, what is that for? Cause either that's an AC breaker used for DC.... or they have AC wiring in the same box/trunking as DC, which is also not allowed.

My goodness, this is an example of how not to do things. This is an installer that knows enough to bootlace crimp the cables for neatness... but not enough beyond that.

They have used that for my genset connection into the 2nd AC input, as far as I can tell.

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