diy solar

diy solar

Butt splice connectors to extend INDOOR PV wire....Why not?

Quattrohead said:
Wire nuts are rated to 600 volts and actually make a great connection. I was very pessimistic when I first came to the USA but now I appreciate them for what they are and how they work.
But yes DC wiring should always be in a metal conduit and box, as the other poster showed here it saved his bacon.
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Didn't know that about wire nuts but the hydraulically crimped and sealed butt splice still seem safer than wire nuts to me, but I digress....thanks.
 
OffGridInTheCity said:
My electrician used but-joints for my PV within a metal connection box and one of them arc'ed/failed in year 4 of operations!
View attachment 203135View attachment 203138View attachment 203140

I repaired it using lugs bolted together but there's 2 more that seem OK - you can see one wrapped in black electricians tape in pic below.
I can only assume the 'bad one' had a loose screw?!? but I don't really have any idea why it arc/burned thru after 4 years. A bit scary to tell the truth.
View attachment 203136View attachment 203139

This was 6awg carrying up to 45a of combined PV about 100ft from the outdoor combiner boxes on the way to the charge controllers.

My advice would be to do it in a proper (metal?) connection box per code (I think it's code to have connection boxes where wires join)

I credit the metal box as protecting me from a fire under the floor of the house.
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A busbar doesn't cost much compared to houses and PV systems. If nothing else, a din mounted breaker works too.
 
energyhunter said:
Didn't know that about wire nuts but the hydraulically crimped and sealed butt splice still seem safer than wire nuts to me, but I digress....thanks.
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What gauge is the wire?Wire?

My bad. 10 gauge.

Wire nuts would work fine. If you're going to crimp, get it from a supply house and not windy nation.
 
You can just use wagos in a box.

Not all wagos accept 10 awg, double check the writing on the side to confirm.

THHN can be used as well.
 
energyhunter said:
I was trying to avoid the bulky ness and more- outdoor-related-need for the MC4s.
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Yeah considering you mentioned 8 wires that would be a fair amount of bulk. There is no problem with using outdoor rated items indoors however the reverse is not true.
 
Wire nuts are the cheapest, and among the lowest resistance- way better than WAGO or MC4.
They are also easy to install and don’t require a torque measuring device.
Why don’t you like them?
 
I don't dislike them...I've used plenty over the years for lights and plugs. I've found so many that were no longer 'tight.' I always tape them too. Technically I understand your point, but I see no arc risk with a hydraulically crimped and marine sealed butt-splice, yet I do not feel the same level of confidence with good-ole' dependable wire nuts. Saving a couple bucks is not on the table for me with this level of risk. I'll bet you that no one ever found a loose wire nut that you installed and I do value your comment, thank you DougfromdaUP.
 
energyhunter said:
I don't dislike them...I've used plenty over the years for lights and plugs. I've found so many that were no longer 'tight.' I always tape them too. Technically I understand your point, but I see no arc risk with a hydraulically crimped and marine sealed butt-splice, yet I do not feel the same level of confidence with good-ole' dependable wire nuts. Saving a couple bucks is not on the table for me with this level of risk. I'll bet you that no one ever found a loose wire nut that you installed and I do value your comment, thank you DougfromdaUP.
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How is it anymore risky than the other 9 billion connections made with wire nuts?
 
For any damp or wet locations, no wire nuts and no split bolts UNLESS you will be permanently potting them with electric safe epoxy. In which case they cannot be serviced in the future.

Other splice methods that use double wall thickness heat shrink with waterproof adhesive are effective as well as epoxy potting kits. But once you heat shrink or epoxy, no servicing the connection except to cut it off.

I have decided to only use the NSI Polaris waterproof submersible EPDM rubber covered wire connectors. Yes, they cost more, but they are easy to install, contain a silicone conducting anti-corrosion gel, and can be easily removed and used again if wires need replacement or upgrading.
 
When I attach wire nuts they are so tight that they are never coming undone and absolutely do not need electrical tape wrapped around them, that is so amateur. After doing 100 or so my arm cramps up so bad I can't even hold a beer 😤
 
Quattrohead said:
When I attach wire nuts they are so tight that they are never coming undone and absolutely do not need electrical tape wrapped around them, that is so amateur. After doing 100 or so my arm cramps up so bad I can't even hold a beer 😤
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Sounds like a professional technique. Can you explain a little how it gets done the right way for me?
 
From your panels to a combiner box you should be using PV rated wire. This wire is rated to be in the air and weather and is also rated to have UV resistant sun protection. From the combiner box/disconnect switches you can use THHN/THWN/MTW which is cheaper and meant to be in conduit. Outdoors you can run PVC conduit and boxes. Indoors of any structure your DC current wires must be in metallic conduit per code. This can be EMT or flexible aluminum. The boxes also must be metallic. If not metallic, a ground wire must pass through them so anything metallic is properly grounded like an outlet in a pvc wall box. The metallic boxes must be grounded which in turn will carry the ground via the metallic conduit to all other metallic boxes and even the inverter and battery enclosure if metallic. If running a ground from your disconnect switch into a structure, this is a ground from a DC source. therefore it can be separated from an AC ground source like a utility grid tied panel. So it would terminate in a grounding rod close to the batteries and inverter. If the inverter is not grid tied, then it needs to be connected to a grounding rod along with batteries and the array. If the inverter is grid tied, then the inverter can be grounded to the AC ground supplied by the grid tied source.
 
glandpuck said:
From your panels to a combiner box you should be using PV rated wire. This wire is rated to be in the air and weather and is also rated to have UV resistant sun protection. From the combiner box/disconnect switches you can use THHN/THWN/MTW which is cheaper and meant to be in conduit. Outdoors you can run PVC conduit and boxes. Indoors of any structure your DC current wires must be in metallic conduit per code. This can be EMT or flexible aluminum. The boxes also must be metallic. If not metallic, a ground wire must pass through them so anything metallic is properly grounded like an outlet in a pvc wall box. The metallic boxes must be grounded which in turn will carry the ground via the metallic conduit to all other metallic boxes and even the inverter and battery enclosure if metallic. If running a ground from your disconnect switch into a structure, this is a ground from a DC source. therefore it can be separated from an AC ground source like a utility grid tied panel. So it would terminate in a grounding rod close to the batteries and inverter. If the inverter is not grid tied, then it needs to be connected to a grounding rod along with batteries and the array. If the inverter is grid tied, then the inverter can be grounded to the AC ground supplied by the grid tied source.
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I bet very few do it this way
 
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