[GreenKeys] Midget twist-lock connectors for power cords - reference

[Nick England]

John is correct about the ML-3R center pin being intended for neutral in a
120/240 system. However you will find this connector used by Teletype and
others for 120v with the center pin as chassis ground. So always double
check when making up a power cord for a piece of gear.

My favorite (not really) gotcha is some military 3-pin power cords with
ground on pin C for early equipment and on pin B for later ones. Danger,
Will Robinson!!

Cheers
Nick K4NYW

On Sun, Jan 30, 2022 at 11:33 PM John W9DDD <w9ddd at tapr.org> wrote:

> One nit I would pick is that for the 7484, the middle pin is not for
> ground, but for the neutral conductor.  Yes it might eventually get to
> ground, but it is considered a circuit conductor back to the breaker (or
> fuse) panel.  Note rating of 15A 125/250V AC, 3 Pole, 3 Wire  vs 125V 2
> pole for the 7593.
>
> In other words the 7484 is designed for use on a 230 volt appliance and
> the 7593 for 115 volt appliances. That being said doesn't mean people may
> have used the 7484 on a 115 volt device incorrectly.
>
> Did I manage to make a mountain out of a molehill or what?
>
> John, W9DDD
>
>
> On Jan 30, 2022, at 5:38 PM, Nick England <navy.radio at gmail.com> wrote:
>
> For future reference,
> NEMA ML-3R 3-pin midget twist-lock female
> 1-11/64" diameter
> NOTE - The ground pin is FEMALE
> example - Hubbell 7484
> https://hubbellcdn.com/specsheet/WIRING_HBL7484_spec.pdf
>
> NEMA ML-2R 3-pin midget twist-lock female
> 1-11/64" diameter
> NOTE - The ground pin is MALE
> example - Hubbell 7593
> https://hubbellcdn.com/specsheet/WIRING_HBL7593_spec.pdf
>
> NEMA ML-1R 2-pin midget twist-lock female - 31/32" dia
> NOTE - no ground pin
> example - Hubbell  7464V
> https://hubbellcdn.com/specsheet/WIRING_HBL7464V_spec.pdf
>
> Having opened my big mouth, I am now sure I have mistyped something -
> double check to be sure..........
>
> Cheers,
> Nick England K4NYW
> www.navy-radio.com
>
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> --
Nick England K4NYW
www.navy-radio.com
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