These are pics of a construction temporary power supply that we (PoCo) metered, energized then later responded to a costomer complaint of "bad power". The inspection process failed miserably here. Local AHJ approved the install, PoCo hooked it up. This is a customer (homeowner) constructed/modified temp. The arc mark came from the customer and a "friend" troubleshooting the install before they called us, evidently they tried to re-install the main bonding jumper. The meter seal was intact when the serviceman arrived. Also notice the proximity to a 75kva pad mount.
[This message has been edited by Trumpy (edited 11-07-2005).]
So for my own edification, let me see if I understand what happened here: Insulated neutral bus was at 120V. Both lugs on the same leg at 120V. All the 240 volt loads would've been supplied with 120, all the 120 volt loads would've been seeing 240.
I can't tell what's going on with any of the grounds or the GEC, but I assume something was grounded somewhere, and when DIY reinstalled the bonding jumper he saw a dead short on the unfused line conductors. The neutral lugs in the meterbase look insulated, but from the size of the scortch-mark, maybe not?
#109585 - 11/06/0511:55 PMRe: Construction Temp. Pics
... Oh well, just when you think you've seen everything,......"I CAN'T BELIEVE MY EYES"!!!!!! Oh,...my brain hurts.. and an AHJ approved it before the PoCo tied it in?? I particularly love the blue jumper... What were they thinking?? They were definitely heading for a "Darwin Award" ..or two... Russ
Oh, and P.S.... What/who finally killed the power?? or did it just melt off the lug?? They couldn't have pulled the meter themselves because the seal was still on it..
[This message has been edited by Attic Rat (edited 11-06-2005).]
.."if it ain't fixed,don't break it...call a Licensed Electrician"
#109586 - 11/07/0501:50 AMRe: Construction Temp. Pics
The neutral lugs in the meterbase look insulated, but from the size of the scortch-mark, maybe not?
Not would be a good guess. The neutral lug is the one in the center, where you see a green conductor terminated. (I have but rarely seen a meter can in which this terminal is insulated.) It's mighty nice of these DIYers to use proper color code so we can dissect their apparent intentions despite the scorch marks. Consider the insulated lug on the lower left to be a hot lug. (Neutral on the right lugs is the correct wiring for a 120V socket meter, but I digress. Such meters are not used nowadays.) Were it not for the PVC nipple, the meter installer would have been the one to see the arc, and it would have been even uglier than this!
#109587 - 11/07/0501:55 AMRe: Construction Temp. Pics