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NEC 83% Rule Liability

14K views 29 replies 13 participants last post by  hornetd  
Not necessarily. It can just be normal types of loads, just at a hugely abnormal amount of load. This is why I said rare. Such a specific type of overload may be so rare that it has never happened, not even once, in all of the 125+ years of the National Electric Code. I'm just wondering who will be liable if (not necessarily when, because it might take 1,000 years for one to finally happen, and the NEC would likely not exist by then) such an event happens due entirely by fault of the coverage hole in the code.
People have and do overload their services all the time. On Long Island I did tons of service upgrades, most were because their existing 100 amp service from the 1960's when the mass-developing started, all the way to homes that just wanted a bigger panel and ran out of slots, planning on expanding, gonna sell etc... But for those who ever actually tripped their main breaker were usually already experiencing other issues like 1/2 the house flickering or always tripping even the smaller breakers anyway and it gets very played if you're service isn't adequate.

Homes wired with 100a if not gas appliances often bought and added them anyway, lots of finished basements with 2nd electric ranges, or it was "cheaper" to buy an electric dryer than the 20-30 dollar more expensive gas model... over the years people added central a/c and that's a tough enough nut to swallow to also have to change to a bigger service. People added built in pools, and hot tubs, and a lot of window unit A/C's if there wasn't a central unit. Over time the normal expected loads add up to outpace the supply you've got and then you know ya gotta upgrade.

Only once have I seen a service entrance cable that actually shorted, of course it was a Federal Pacific Split Buss and they put a 60 amp apartment subpanel in the slot not protected by any main, And the total load of this 1 family home illegally converted into at least 3 seperate units each with electric ranges was way more than that poor #4 alumiun SEU cable between the meter and the panel melted right up, over time the bare copper #6 which was routed through the same bored holes for the SEU cable probably got very hot as well since the outdoor SEU between meter and weatherhead was perfectly intact.

This was a house On Pond Path or Farm-To-Market Rd if I remember correctly.