Reminder: Never connect a generator to home wiring without transfer switch

Mon Aug 30 18:05:16 UTC 2021

On Mon, Aug 30, 2021 at 1:57 PM Tom Beecher <beecher at beecher.cc> wrote:

> There are usually redundancies built-in when it comes to safety.  i.e.
>> what's the point of installing grounds on the upstream side if you have the
>> switch open?  If the lines are de-energized, why wear gloves?  If you're
>> doing all that, why carry an AED?
>>
>
> My uncle was a high tension lineman for much of his career. He was
> frequently on response teams that went all over the country helping restore
> power after severe weather or natural disasters.
>
> There are not 'usually' redundancies. There are ALWAYS redundancies.
>

Yup - and even with this, "an average of 45 linemen a year loses their
lives in the line of duty, leaving families who depend on them." --
https://fallenlinemen.org/frequently-asked-questions/
The original point remains: "Reminder: Never connect a generator to home
wiring without transfer switch".

> Because in that world, especially doing restorations, there are rarely
> opportunities to learn from a mistake.
>

Indeed.
W

>
>
> On Mon, Aug 30, 2021 at 1:48 PM Aaron C. de Bruyn via NANOG <
> nanog at nanog.org> wrote:
>
>> During the February 2021 storm that swept through the US, power got
>> knocked out on my rural street due to a tree coming down and taking out a
>> pole.
>>
>> While they were waiting for a few more trucks to arrive with a
>> replacement pole, I got to ask them a few questions.  They said it's
>> standard practice for them to ground on both sides exactly for the reason
>> that someone might accidentally connect a generator.  They open the nearest
>> switch on the upstream side, test to make sure the line is dead, install
>> grounds on all the wires, then test the downstream side and attach grounds
>> to all the wires, effectively making the work zone an isolated segment.
>>
>> I doubt it's "if you follow every step perfectly at all times and never
>> make a mistake".
>> There are usually redundancies built-in when it comes to safety.  i.e.
>> what's the point of installing grounds on the upstream side if you have the
>> switch open?  If the lines are de-energized, why wear gloves?  If you're
>> doing all that, why carry an AED?
>>
>> -A
>>
>> On Mon, Aug 30, 2021 at 10:19 AM Warren Kumari <warren at kumari.net> wrote:
>>
>>>
>>>
>>> On Mon, Aug 30, 2021 at 12:47 PM Aaron C. de Bruyn via NANOG <
>>> nanog at nanog.org> wrote:
>>>
>>>> I've been following the thread.
>>>> If I'm dumb enough to back feed through the transformer into the
>>>> downstream side of the downed line, how is it going to be a problem if
>>>> linemen are grounding the phases on *both sides* of the work area.
>>>>
>>>
>>> I suspect that there is a non-zero amount of "in an ideal, perfect
>>> world, when all of the wires are simply lines on a piece of paper, and you
>>> can look at them from the comfort of your office chair, this is easy" -
>>> but, in the real world, linesmen are rushing about and trying to get the
>>> lights back on, cut through the big ash tree that is wedged between the oak
>>> and the pole, etc. Even the nice idea of "well, just take the conductos and
>>> tie 'em to ground" means that you need to go trudging through hedges and
>>> vegetation and tree limbs and lions and tigers and bears, often while it is
>>> pissing down with rain or baking hot.
>>>
>>> I guess I'm missing how we've moved from the "some people are putting
>>> their lives on the line, let's try to make their life less dangerous" into
>>> a "weeeeell... if they simply followed these set of steps perfectly at all
>>> times, and never made a mistake they'd be fine."
>>> This is NANOG -- I'm sure that we've all followed a set of steps
>>> perfectly and still managed to redistribute BGP into the IGP, or apply an
>>> ACL and lock ourselves out of a box, or types "show run" and watched the
>>> router randomly reboot. Now consider this, but with the added drama of
>>> potentially ending up dead...
>>>
>>> W
>>>
>>>
>>>> That's what Ben seemed to be implying.
>>>>
>>>> -A
>>>>
>>>> On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman <mel at beckman.org> wrote:
>>>>
>>>>> Aaron,
>>>>>
>>>>> If you read back in this thread (using the NANOG mailing list
>>>>> archive), you’ll find this has been explained in great detail. In a
>>>>> nutshell, phase grounding won’t help if a generator is energized from the
>>>>> customer end, and this technique was discontinued in the 1970s due to the
>>>>> many deaths that resulted.
>>>>>
>>>>>  -mel
>>>>>
>>>>> On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG <
>>>>> nanog at nanog.org> wrote:
>>>>>
>>>>> 
>>>>> On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
>>>>> lb at 6by7.net> wrote:
>>>>>
>>>>>> Yes, this is a real and dangerous problem.  Today.  Even with
>>>>>> grounding I’m afraid.  Source: I’ve been working in an engineering capacity
>>>>>> for 27 years and I have the license you’d need to build a nuclear power
>>>>>> plant.
>>>>>>
>>>>>
>>>>> Would you care to educate me on this?
>>>>> If you ground the phases on both sides of the work-site, how are you
>>>>> going to end up being a better path to ground?
>>>>>
>>>>> -A
>>>>>
>>>>>
>>>
>>> --
>>> The computing scientist’s main challenge is not to get confused by the
>>> complexities of his own making.
>>>   -- E. W. Dijkstra
>>>
>>

-- 
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra
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