[Info-vax] grounded MMJ cables

Michael Moroney moroney at world.std.spaamtrap.com
Sun Jul 18 12:34:58 EDT 2021


On 7/18/2021 8:50 AM, chris wrote:
> On 07/18/21 12:08, Phillip Helbig (undress to reply) wrote:
>> In article<sd10f5$pd6$1 at gioia.aioe.org>, chris
>> <chris-nospam at tridac.net>  writes:
>>
>>> On 07/18/21 09:35, Phillip Helbig (undress to reply) wrote:
>>>> In article<sd0n91$i5o$1 at tncsrv09.home.tnetconsulting.net>, Grant Taylor
>>>> <gtaylor at tnetconsulting.net>   writes:
>>>>
>>>>> On 7/17/21 11:22 PM, Phillip Helbig (undress to reply) wrote:
>>>>>> I'm testing out some MMJ cables (useful for console cables) and
>>>>>> notice that some (all of which are round rather than flat) have an
>>>>>> additional wire outside of the plug at each end, which looks like it
>>>>>> might be intended as ground.  What's the purpose of that?
>>>>>
>>>>> How long is it?  I'd expect it to be 3-9 inches if it's meant to be a
>>>>> ground wire that is attached to something else on the chassis.
>>>>
>>>> Yes, about 5 inches.  It has an eyelet at the end, so one could connect
>>>> it to the chassis via a screw.
>>>>
>>>>> I would also have significant worries about ground loops and / or 
>>>>> sneak
>>>>> currents.  Both of which can be quite dangerous from an electrical and
>>>>> safety perspective.  As in more amperage than the wire can safely 
>>>>> handle
>>>>> turning the wire into a heater that can melt insulation and start 
>>>>> fires.
>>>>
>>>> But is that an issue when using a console cable?
>>>
>>> Not usually from an interference to the cable  point of view and iirc,
>>> the added wire is at one end only, which would not enable earth loops.
>>
>> I have seen those, but the two I checked today have it at both ends.
> 
> Ok, but the one I have has just one, but maybe that was third party
> item.
> 

I have never seen anything like that on a DEC MMJ cable.



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