[RE-wrenches] Hazards of underground feeders

Wed Sep 9 18:55:51 PDT 2015

Sorry to hear about that tragedy William. As a volunteer firefighter, (and of course a huge proponent of solar safety), I'm 100% supportive of, and encourage the use of "rapid" shut-down right at the module.

Eric Stikes
Founding Director, GoodSun Solar
A 501(C)(3) CA. Non-profit Corp.
001.530.798.3738 (cell)
www.GoodSun.life
[sent via pigeon...or cell phone]

> On Sep 6, 2015, at 11:35 AM, jay peltz <jay.peltz at gmail.com> wrote:
> 
> Dear William,
> 
> I like all of your ideas, but they have one thing in common, they are all passive.  All the placards/labels/signs  in the world won't prevent someone from not reading or acting or miss understanding them.  So I totally agree with the NEC that we need automatic disconnects that prevent such events in the future.  
> 
> I think this kind of sad event is the reason for the NEC to require array/string level disconnect.  
> From what I've heard and I'm sure others are well more versed than I, but we will see module level shutdown required in 2017 NEC, and I for one welcome that.
> 
> jay
> 
> peltz power
> sent:  11.35am 9/6/15
> 
> 
> 
> 
> 
>> On Fri, Sep 4, 2015 at 2:21 PM, William Miller <william at millersolar.com> wrote:
>> Dear Friends:
>> 
>>  
>> 
>> Last week a local well technician was electrocuted.  I had just met him in conjunction with a job we are about to do and realized right away he was a very nice person.  He left behind a wife and two teenagers.  Most tragic, his wife was working with him when it happened.
>> 
>>  
>> 
>> The scenario is still not fully understood but here is what we do know:
>> 
>>  
>> 
>> 1.    The fellow was digging with a mini-excavator.
>> 
>> 2.    He knew buried lines were present and had turned off all circuits he thought were included.
>> 
>> 3.    He struck a power feeder.  We don’t know if it was direct bury or in a conduit or if it was AC or DC.
>> 
>> 4.    Based on his impression the conductors were all dead, he jumped into the ditch with uninsulated dikes to cut the wire.
>> 
>> 5.    He had one hand on a t-post and the other on his pliers.
>> 
>> 6.    His wife grabbed his clothing but could not get him to release his grip.
>> 
>> 7.    An AT&T tech was nearby and donned hot gloves to pull him off the circuit.  It was too late.
>> 
>>  
>> 
>> This is an important issue for all of us.  We work with high voltage regularly.  We need to think about how to avoid this. 
>> 
>>  
>> 
>> I have connected with high voltage AC many times.  My body always reacts to retract from contact.  I got across high voltage DC once.  I could not let go.  I had to will myself to throw my arms down to break contact.  The experience was frightening.
>> 
>>  
>> 
>> On our crew we are integrating what we hope will be reflexive responses to given procedures.
>> 
>>  
>> 
>> One is this:  Every time you turn off a breaker to work on a circuit, the next thing you touch is a meter to check that the circuit is de-energized. 
>> 
>> Two:  Don’t trust your inductive tester.  It will not detect DC.  It will not always indicated voltage present.
>> 
>>  
>> 
>> This accident was at a local winery.  Many wineries in this region have ground-mounted PV systems, many remote from the main service, therefore they have underground feeders.  Most are string configured systems meaning the feeders are high voltage.
>> 
>>  
>> 
>> It occurs to me that the uninformed worker might assume that turning off all the circuit breakers at the meter will de-energize a circuit, should it be compromised.  Turning of the AC breakers would not de-energize a DC PV feeder.  This is a problem.
>> 
>>  
>> 
>> I spoke with another well technician about this .  He was not aware of the safety issues associated with PV feeders.
>> 
>>  
>> 
>> What to do?  Here are a few suggestions:
>> 
>>  
>> 
>> 1.    Mark all conduits with bury tape 12” above the conduit.  This does require extra work, you have to make two runs backfilling.
>> 
>> 2.    Sign the meter panel with an indication that opening all the circuit breakers will not de-energize all circuits on the property
>> 
>> 3.    Include your contact number so you can easily be contacted to reinforce the steps needed to be taken to excavate safely.
>> 
>> 4.    Always include disconnecting means at a ground-mount array.
>> 
>>  
>> 
>> This issue is specific to excavation operations, but this reminds me of why I am so picky about wire shielding on ground mount arrays.  This tragedy could easily happen to a child climbing on a ground-mount rack.
>> 
>>  
>> 
>> Please add your thoughts on how to best manage the safety issues presented.
>> 
>>  
>> 
>> William
>> 
>>  
>> 
>> <image003.jpg>
>> Lic 773985
>> millersolar.com
>> 805-438-5600
>> 
>>  
>> 
>> 
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> 
> 
> -- 
> Jay Peltz
> Peltz Power
> jay.peltz at gmail.com
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