question

Stan avatar image
Stan asked

Conduit size MultiPlus II 24/3000

MultiPlus II 24/3000 is 500 miles away. Prepping to install output to a breaker panel. Would like to run 6g thhn in conduit to the panel. What size holes are on the bottom of the MultiPlus II for conduit connection? Are thread connectors the same size on flex and schedule 40? I didn't see any reference to size required in the manual online. Thanks.

Multiplus-II
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4 Answers
proton avatar image
proton answered ·

They are protected by some grey rubber,complet closed. you can cut them and fit to different cable diameters. Biggest one is marked as „19-21“ mm. Same for all holes.


p.s. Without the rubber, its 25mm diameter

bye

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Jim avatar image
Jim answered ·

As mentioned, the openings in the bottom of the 3000VA Multiplus II are 25mm. This is unfortunate, being in North America, a standard 3/4 trade size is about 1mm too big. It is worth noting that this is also a 120VAC 60hz inverter too. Of course all of my conduit and fittings are NA sizes. Ideally, there is a 25mm to 3/4 EMT fitting out there... still looking

4 comments
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kevgermany avatar image kevgermany ♦♦ commented ·
25mm is so close to 1" that you could probably work with that.
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Jim avatar image Jim kevgermany ♦♦ commented ·

It is just barely too small for the connectors to go through. 3/4" trade size requires a 27mm hole: https://www.nema.org/docs/default-source/technical-document-library/bull_71_reaffirmed_12_15_11.pdf

Victron really should have considered this for sale in NA, but I have not given up yet. I really don't want to drill my new inverter either.

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Alexandra avatar image Alexandra ♦ Jim commented ·

Is this a more than one core cable?

If it is you strip the outer insulation off and pass the coloured cables through the glands.

And no don't drill or modify it voids the warranty

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Jim avatar image Jim Alexandra ♦ commented ·
Thanks Alexandra. I think there is a misunderstanding about what I and others are needing to achieve. We do not want to use the rubber glands, for various reasons, including regulations. I added another response with a video that may help below.
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Jim avatar image
Jim answered ·

I have not given up yet.

Here is a video of another person running into the same problem with their MultiPlus II 120V in the USA. He has the 5KV version. His solution is interesting. @Victron, or anyone else at Victron, any thoughts on the problem we are faced with the 25mm opening in North America? I cannot find a fitting to use EMT (metal conduit here in NA) that would also use the 25mm opening in the MultiPlus II. The USA uses "trade size" when defining openings for connectors and conduit. It is a number that is supposed to tell the maximum diameter of a bundle of wire that can run in a certain size conduit. 1" trade size conduit then, is supposed to pass a bundle of wires up to 1 inch in diameter (25.4mm). To do this, it requires a knockout hole of 27mm minimum, as defined in the NEMA doc listed in the response above. I realize putting this size of a knockout in the inverter could change the UL testing, so it is not an easy change to make.

Yes, this whole historic business of "trade size" instead of just a measurement is rather silly, but here we are, and the inverter is marketed with 120V 60 hz with UL for North America.

Any thoughts?

https://youtu.be/pi5M6XrDSjo?t=310


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tyler-pomerhn avatar image
tyler-pomerhn answered ·

(Sorry if I'm "zombie-ing" the thread but I just caught this page on a search of my own)

I really wish Victron would do two things - one is make a 120V Multiplus-II 10k (wishful thinking), and the other is conduit usage.

I don't really understand why Victron is the only top tier manufacturer that still insists on "baring all" when it comes to cabling. And it's not that it's an "option" to use conduit or not, it's specifically forbidden in some of the documentation (Quattro docs explicitly state not to run battery cables in conduit - WHY?). The inability to allow for conduit to make the installation look professional is beyond me.

Victron's chief competitors in this space all have excellent cable management, either in proprietary wireways or support for conduit. Schneider, Sol Ark, Tesla - heck, even EG4 - the list goes on and on... all have (usually optional) wire management in their top tier products. But Victron? Try and get conduit run to a Smart Solar SCC. Or hiding Lynx Distributor wiring. You can't. Not really. Not more than a "hack" of wireways smushed up under the units.

I'm considering a three-phase 208/120Y system with three 10k Quattros, but I will not do it with exposed wiring. Period. That means I can't use the Lynx at all, I have to have NEMA boxes for things like Cerbo and DC bus bars/shunt, etc... I may skip Victron altogether based almost exclusively on this point.

Victron should absolutely step up their game here and at least allow conduit as a formal option.

3 comments
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Justin Cook avatar image Justin Cook ♦♦ commented ·
High-current DC cabling is not generally advised to be placed in a closed conduit because it diminishes the heat dissipation capability of the wire, which negatively impacts the ampacity of the wire.


For most of the 120v Quattro line, 4 DC cables will be used (2x positive + 2x negative) so, for instance, on the 12/5kVA that would be (4) 4/0 cables bundled together, and where a single 4/0 cable has a maximum continuous ampacity of 445A (assuming high-quality UL1426 marine wire), that same cable when bundled with 3 other cables now only has a maximum continuous ampacity of 267A.


That too is assuming "typical" ambient temperatures, whereas the same setup of (4) 4/0 cables inside, say, an engine room with high ambient temperatures, each cable would only have a maximum continuous ampacity of 226A.


Obviously this will make proper fusing very difficult, since where you could fuse a wire at 400A now you have to fuse it at 200 or 220A, in which case you would likely be quite routinely blowing fuses. So although Victron's admonishment against installing the wires in closed conduit may be an aesthetic nuisance, A. a raceway would be fine, and B. I'd personally much rather an installation be slightly less aesthetically pleasing than have to deal with either blowing fuses all the time or risking melted wires and potential fire... but maybe that's just me.

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Alexandra avatar image Alexandra ♦ Justin Cook ♦♦ commented ·
Yes this.


High current cabling gets hot. Enclosing it makes it worse. Or you have to upsize even more. So adds expense.

Having them exposed means visual checks on system health is easier. Better maintenance and prevention of fire hazards.

So really way more reasons to be exposed than enclosed.

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tyler-pomerhn avatar image tyler-pomerhn Alexandra ♦ commented ·
I suppose we'll have to agree to disagree, then.

While the points about "now you have to factor in the heat and combined conductor capacity" are absolutely correct and valid, it still flies in the face of, again, EVERY other manufacturer either having conduit boxes they make, themselves, and enthusiastically promote/endorse (EG/SCH) - or how every installation I've seen for some manufacturers on YouTube shows their units utilizing conduit and wireways (SMA/SA).

Up until a year or two ago, it was mandatory code compliance on the island we're building on to have conduit for every wire run, including service entrance, to junction boxes, light switches/outlets... you name it. Now it's just "suggested" but not mandatory.

While exposed wires allow for easier visual inspection, they also invite potential electrical hazards from physical abuse because they are exposed/unprotected.
Conduit also protects wires from accidental physical abuse and environmental effects, such as aerosols, airborne particles, and the reverse of the issues that you mentioned, cold! If i was in a cold climate I would surely prefer the wires to stay warm instead of potentially having their insulation become brittle, and factor in the reduced ampacity accordingly.
I'm not saying we all "must" use conduit or wireways. I'm just saying that completely negating even the possibility of it is an odd choice for a Tier 1 manufacturer, and will cause some to not buy Victron as a consequence. I would much rather buy other manufacturers for this very reason, but I may "have to" buy Victron because it's locally source-able on the island (shipping in huge inverters may not go well!). However, if I do go Victron, I absolutely will have conduit. For me, there is no alternative.
Thanks for your comments, and again, I hope that there are other options available to Victron customers in the future for those who don't like having their cables exposed in C-clamps on a wall board.

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