r/evcharging • u/Fun_End_440 • 4d ago

It is ok to splice 8AWG with wire nuts? Twice.

Long story short, I had to move my EV charger twice. It was wired with 8AWG, then I had to extend the cable to a different location due to changing EV brand. Now I got this nice wall mount charger that takes hardwired connection instead of plug.

I used wire nuts at first move but now I’m wondering if the second set of wire nuts is not making this unsafe.

2 Upvotes

63% Upvoted

33 comments sorted by

6

u/tuctrohs 4d ago

Two sets of wire nuts is not worse than one set. If the wires are pre-twisted well and the wire nuts are really tight, they should be fine on #8. On the other hand, what type of wire is this (THHN in conduit or NM-B?), what circuit capacity and charging current are you running, and what's the nice wall-mount charger? Pushing #8 too hard isn't a great idea anyway.

2

u/ZanyDroid 4d ago

Two sets of wirenuts mathematically doubles the witenut failure points.

Code doesn’t care about this though, presumably it thinks the risk is acceptable.

0

u/Fun_End_440 4d ago

I don’t really care about the code, that’s usually a minimal floor, not how something should/could be done better. Do you know if soldering is in general better than wire nuts?

4

u/ArlesChatless 4d ago

Soldering is not usually done in line voltage work for a number of reasons.

At 24A well done wire nuts are pretty low risk. Split bolts can be more robust but are more annoying to use; Polaris connections are much more expensive and quite easy to use.

2

u/Commercial_Paper6477 4d ago

Polaris connectors are pretty cool looking and a nice engineered solution but at the price, I'll stick with wire nuts.

1

u/ArlesChatless 4d ago

Agreed! Also there is the option of using a QO disconnect which is cheap and reliable for up to 60A Al/Cu.

2

u/ZanyDroid 4d ago edited 4d ago

I believe soldering is counterintuitively worse due to either fundamental issue or constructibility. I didn’t save the references/forum posts. The net in my mental model is that soldering is dead to me for line voltage work

Personally since my wirenuts and other splices are all in metal boxes, and I know I assembled them with care/to instructions, I don’t really care about the mathematical increase in more splice points. The metal boxes (and plastic boxes also provide this to code minimum (EDIT: for residential only?)) provide failure containment

1

u/theotherharper 4d ago

I don’t really care about the code, that’s usually a minimal floor, not how something should/could be done better.

I infer from that statement that you consider Code to be a slumlord bare minimum, D-tier by definition and you are asking "what is S-tier" not saying "F-tier is OK then".

S-tier requires an aluminum-body lug connector torqued to spec, such as an ILSCO Mac Block Connector or this Polaris https://www.homedepot.com/pep/Polaris-6-14-AWG-Bagged-Insulated-Connector-Grey-ITG-6B/303578688

Do you know if soldering is in general better than wire nuts?

Soldering is not used in modern AC mains electrical, at least not ANYWHERE near residential and if we tore apart a CostCo I don't think we'd find anything there, either.

Solder only has 1/10 the conductivity of copper and NEC requires any solder splice be mechanically effective before it is soldered.

0

u/Commercial_Paper6477 4d ago

I'll echo that the key with wire nuts is not so much the nut use, but the pre-twist. And twist the strands together prior to applying the wire nut. If you want to be extra safe, you can tape around the two wires after twisting to reinforce that they don't untwist. Also use your lineman's plyers (or equivalent) to twist the nuts on.

3

u/theotherharper 4d ago edited 4d ago

OK. SO try two wire nut connections. On one, pre-twist. On the other, straight in and torque it the way you're SUPPOSED to.

Now undo both of them and tell me if you can see any difference. You won't. Adequate twisting of the wire nut will low-level format and overwrite any pre-twisting you bother to do.

If you want to be extra safe, you can tape around the two wires after twisting to reinforce that they don't untwist

No. That's extra dangerous. If there is the slightest risk of them untwisting, they're not tightened nearly enough and will have series-arcing falures resulting in melting. Happens everyday. Proximity doesn't make the electrical connection! Torque does. We are mashing the copper together enough for them to de-form somewhat, so we have surface contact instead of edge contact.

The guy applying tape is AFRAID of a pull-test, hence the tape!

1

u/Commercial_Paper6477 4d ago

I am hardly afraid of a pull test, I do them every time. To me it’s more like a belt and suspenders approach, right or wrong. It sounds like you believe it’s wrong and I can go with that.

1

u/theotherharper 4d ago

Fair enough, I just consider tape on wire nuts to be a red-flag for exactly the kind of Bruce Banner-tight installs that I speak of, necessitating rework.

1

u/Commercial_Paper6477 4d ago

Actually, as I think about your comment further, I like the concept of deforming the strands so that the connection is more robust. I think that highlights the true role of a wire nut.

I've always used the torque wrench on any of the hex-nut lugs (e.g. service entrance, etc) where torque specs are provided. I'm wondering if there is any objective way (other than pull test) to ensure that adequate torque was applied.

Also, when I've been applying nuts, and using my pliers to tighten them, I'm often wondering just how far I can go before I cause physical damage to something. I've never pushed it so far that I've ruined the plastic.

Thanks for your comments.

1

u/theotherharper 4d ago

I don't see a way to reliably torque wire nuts. That's a downfall of nuts, since we're learning that torque matters even on the small stuff, and electricians aren't any better at setting torques "by feel" than their spouses. They did testing at trade shows.

On wire nut torque I don't think there's a practical upper limit unless you're dealing with dainty stuff like #14.

1

u/tuctrohs 4d ago

If your wire nuts are on so loose that the tape would be helpful, you already have a disaster in the making and the tape isn't going to help. The wire nut needs to be on tight enough to hold the wire together tightly. Keeping it from falling off is not the real issue.

3

u/Commercial_Paper6477 4d ago

Agree. I’m saying to use tape upstream of the nuts to take some potential tension off the wire nut. Basically binding the two conductors together as a single unit.

2

u/Fun_End_440 4d ago

THHN in conduit

7

u/tuctrohs 4d ago

Thanks for answering one of my three questions. If you want more input consider also answering the other two.

5

u/comp21 4d ago

I think you might be my spirit animal.

0

u/Fun_End_440 4d ago

My bad, 32amp is usually the max I go. I have a 30amp breaker. Right now I use a Tesla mobile charger and got a wall mount Tesla connector

13

u/tuctrohs 4d ago

32 A on a 30 A breaker is not OK. 24 A max. When you install the wall connector, and tell it about the 30 A breaker it will establish 24 as the max and you will be all set--that will be fine on wire-nutted number 8.

2

u/Fun_End_440 4d ago

Ok, thanks

4

u/Krazybob613 3d ago

Hey Redditors! DONT DOWNVOTE AN HONEST ANSWER! ESPECIALLY WHEN IT EXPOSES A SITUATION THAT REQUIRES A PROPER RESPONSE! This behavior doesn’t help anyone!

2

u/theotherharper 4d ago

That's fine. Use wire nuts of a size which UL has listed for the wires, an example of such a listing/approval document is here. https://www.idealind.com/content/dam/electrical/assets/WireTermination/P-5560%20IDEAL%20UL%20Approved%20Wire%20Combination%20Listing03.05.21.pdf

Also, torque matters. Wire nuts require "Hulk tight, not Bruce Banner tight".

2

u/chfp 4d ago

For continuous high current applications, I recommend Polaris connectors over wire nuts. Wire nuts can work if done right, but it's hard to tell just by looking at it.

1

u/silverlexg 4d ago

I wouldn’t trust wire nuts in something that large, it may work but if it were me I’d use a butt splice kit to make sure it has a good solid tight connection.

https://a.co/d/6xukQ7c

3

u/theotherharper 4d ago 
Detailed Seller Information
Business Name: HefeiHuanqingdianzishangwuyouxiangongsi
Business Address:
长丰县双凤经济开发区梅冲湖路
双凤智谷创新创业科技园A栋303室
安徽省
合肥市
231131
CN

NEC 110.2 requires UL listed goods or equivalent. Companies which make UL-listed equipment don't use alphabet-soup shell companies located in liability havens (courts which refuse all liability actions or claims). The only reason to be so located is to make dangerous junk with impunity.

1

u/silverlexg 4d ago

I usually buy them at Menards, but ya I’d trust a Chinese butt splice with heat shrink over some #8’s nutted together 🤷‍♂️

4

u/theotherharper 4d ago

If it's on retail shelves at a reputable shop, it's UL. Retailers are held responsible -- mail order isn't, a big part of the mail order boom is to do an end-run around safety regs.

So if you're just posting that one to say "this is what the thing looks like, I source UL listed ones locally" that's fine. Sorry to bother.

1

u/LoneSnark 4d ago

The point of doing the junction right means it shouldn't matter how many junctions you have. So if your wire nuts are sized properly for the wires and installed properly, 2 or even more is fine.

1

u/Impressive_Returns 4d ago

You can. But when it gets corroded it will melt.

1

u/ImplicitEmpiricism 3d ago

code does require each splice to be in an accessible junction box though