Quote:
Originally Posted by timun
Okay, I stand corrected. I've only ever seen the purple Al-to-Cu ones. I'll freely admit this limitation is completely irrelevant to me as I have no aluminum wiring in my house, but it stands to reason a professional has to deal with Al-to-Al sometimes.
I thought you meant that the mechanical connection is worse. From the youtube videos I've watched of people using them they're very snug and resist a tug test better than a wire nut.
With respect to the electrical connection, I would imagine they have a slightly higher resistance because the conductors are not in direct contact, but I find it incredulous that it'll make much of a difference. At least, on typical 120 VAC/15 A circuits the likes you'd find in a house.
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The tensile strength of each type has its limitations, if you're using wagos to connect to a load with a modest amount of current flowing as well as vibration (aka a small transformer) they operate worse mechanically than a wire nut. Tug test they are probably better but that isn't very relevant as you'll never be tugging on a wire once it's installed.
The difference is huge in electrical connection. Take this video for example:
In this video, he uses only 1A of current for the test (he should be using closer to 20A to actually stress the connection for a useful result). Long story short he gets 6.8 mOhm of resistance at 1A for the wago and 6.5mOhm for a wire nut.
Those are useful to know, but had he used 20A and measured watts lost (aka heat generated) from the connection using the formula P=I^2 X R.
P=20^2 x 6.8 = 2.720W lost from the wago + wire
P=20^2 x 6.5 = 2.600W lost from the wire nut + wire
This equates to a 5% increase in heat generated by a wago. Heat related failure is also not linear when it comes to equipment lifespan, its actually exponential so a 5% difference is substantial.
Of note, he didn't strip back enough on the wire nut to meet the manufacturers spec. He also didn't pre twist the wires which is a manufacturer spec but is not consistent with best trade practices. The value of 6.5mOhm could be dropped even further with having a larger contact area and pre twisting the wires.
This is all napkin math and there will be some rounding errors here, but for all intents and purposes it demonstrates my point.