Anyone ever here of a difference between AC and DC rated Wirenuts? Dang inspectors.

[Rocksteady2R]

So we're at an inspection today and pop a box. Inspector says "are those wire nuts rated for DC? You know there's a difference, right?"

Is he smoking crack?

am I, and my entire bloody team, frigging ignorant?

I've never heard of one, and I'm not finding a reference anywhere through google. and I can't, through everything I know (I'm no Tesla), imagine that there would be a difference in a simple wire connection like that.

any references would be great.

[GFS]

Hi Rock,
I think he's smoking crack. At the very least he should provide you with documentation that backs up what he is saying. Per this link wire nuts are rated for peak voltage and the wire size they can handle, not whether or not the electricity passing through those wires are AC or DC: http://www.electrical101.com/wire-connectors.html

For the same wattage rating, a DC system has lower peak voltage needed than an AC system. So, just assuming he is correct, "AC" rated wire nuts have to withstand a higher voltage for a given wattage rating than "DC" rated wire nuts. For this very reason, your inspector is A) either pulling your leg or 2) wants to see if you understand the difference between AC voltage/amperage and DC voltage/amperage.

Gordon

[Mike90250]

I think wire nuts are a mistake for solar PV. The power is constant for 6 hours in a hot environment. Split bolts or splice blocks would be a better choice for reliability.

As for AC or DC, I don't think it's the type of power, but that the DC is on and cooking the nut for hours.

[solarix]

The boundary between "low voltage" and "medium voltage" in the NEC is 600V. All wiring devices generally need to meet this minimum requirement, just like THHN wire is rated for 600V. So, AC voltages are an RMS (root-mean-square) measure of the average voltage and for a sinusoid AC, that means the peak voltage is 1.414 times the rating or almost 850Vpeak. Whereas the peak DC voltage would just be 600V. However, from a power perspective, the power flowing through either a DC or AC 600V circuit would be the same, thus the power loss (and wire heating) is the same, which is the whole point to rating AC in Vrms. Wire nuts are listed for use up to 600V and would work equally well whether AC or DC. You could argue that AC could be harder on the wire nut because the peak voltage it could see are higher.
Be aware that there is a lot of quality variation between wire nuts. Some of them I wonder how they pass UL tests. I know I've seen them with the plastic split open.

[Sunking]

There is no difference between DC and AC Wirenuts. However there is a huge difference between Outdoor rated and Indoor rated Wirenuts. The bigger issue which is a design issue rather than code is Wirenuts should not be used. Use them at your peril. If you are using Indoor rated wire nuts outside, good luck.

[Rocksteady2R]

Alright.

So a morning of phone calls and chat rooms with tech support and fine print on the spec sheets and this is what we have.

a) 3m wire connectors part no. 054007-43154 (the fairly common red/yellow wire nuts)
b) The are UL listed and... Those UL test conditions are defined by AC Current.
c) talked to both 3m tech support engineers, and a consulting engineer of theirs and neither they, nor their impromptu round-tables around the offices they were in, knew of a DC wire nut - but they couldn't come up with a "why" - just that it never was. No one saw a feasible reason why they wouldn't work, but that ends up being moot. Listed is as listed does.

so... yeah... now we go back to old solutions. good good.

And that's that.

[littleharbor]

Could he be referring to these direct burial/waterproof wire nuts. I believe they are used in low voltage dc landscape lighting.

https://www.bing.com/images/search?q=Waterproof+Wire+Nuts&FORM=RESTAB

[Sunking]

If they are not tested and listed the Inspector has you by the balls. He already planned to fail you and just found the reason. What it boils down to the root of the problem is who installed it. I do not know of any contractors who would use Wire Nuts. All I know of use Term Blocks and H-Taps.

Remember the two Golden Rules of dealing with Inspectors.

1. Inspector is always right like your wife.
2. If Inspector or Wife is wrong, refer to rule #1.

Comply with those two rules and you will pass inspection and stayed married. Otherwise one of them will screw you, and the other will never let you screw them again.

FWIW the Inspector has you with a technicality. He is completely right stating the Wire Nuts are not rated or tested at DC. You cannot win the argument because of Article 90.7, 100, and 110.3. If you challenge and go to arbitration, that is what they will hit you with and there is NO DEFENSE for ignorance. If you think he is tough now, challenge him and see what happens.

Its a dirty deal, as some Inspectors may let it fly, and others will not.