[RE-wrenches] mystery amperage disappears & re-appears in AM

[Dana]

Many years back, I had a similar problem with a remote offgrid new client with an existing system: 

Early morning resulted in voltage & "some amperage" but not what they used to get.
Then as the day progressed amperage dropped off but voltage remained constant as though under load not open circuit.
I checked everything I could find and asked if there were any more connections, "no there were not" was the response.
On the third trip there they "remembered" a junction box under the front of the house.
Opening the metal 16x16x6 J box yielded 2 split bolts burnt touching the box & taped with temp wrap black electrical tape (now burnt) at what was originally only 3 layers of wrap. Yikes!
Replaced both split bolts, trimmed the wire back (fortunately there was excess in the box) and covered with rubber lineman's tape and all was well.

Point here are the metal box probably saved a house fire those suckers were really hot by midday, & thankfully today we have much better alternatives to split bolts.
The regular re-torque & inspection of mechanical connections is a very good idea & a way to reconnect with clients and keep the system operation & safety up to par.



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Dana Orzel 
Great Solar Works, Inc -  NABCEP # 051112-136
E - dana at solarwork.com  - Web - solarwork.com 
O - 970.626.5253  C - 208.721.7003
"Responsible Technologies for Responsible People since 1988"  
 Please consider the environment before printing this email.


-----Original Message-----
From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Daniel Duffield
Sent: Sunday, November 01, 2015 12:46 PM
To: re-wrenches at lists.re-wrenches.org
Subject: Re: [RE-wrenches] Classic 150 100 amp output breaker tripping

Some years ago, we had a similiar problem with a 50 amp breaker nuisance tripping, we over  analyzed the problem and still could not prevent this erratic issue, sometimes it would work fine for weeks - sometimes days apart, sometimes on sunny days, sometimes on cloudy days.
 In the end the answer was simple and so easy it was overlooked more than once. 
It was just a matter of the proper torque, with the copper compression fitting on a Sq D QO breaker, just a hair breathe too loose, enough heat would build over many hours to change the trip curve. 
We measured, swapped breakers, everything you could think off until we employed a torque wrench with a screwdriver bit. 
Problem vanished, never to come back. 
Not saying this is answer, but sometimes tightening a compression fitting to the correct "feel", by a journeman electrician with 20 years experience, is not good enough. If your crew or organization has torque screwdrivers, we had no excuse not to use them, and back then we found out the hardway.

Daniel O. Duffield
NABCEP Certified PV Installer since 2005 EE 98 & ER01, Albuquerque, New Mexico, IEEE member 1995 DPW Solar (Integration-Division)
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