Crazy Ideas

Curious how many of you out there have had to deal with crazy install requests and how crazy were they?

My most recent:
Client asked if he could provide his own wire (he is an electrician of questionable reputation). I sized his DC run to the Inverter at #6 with a .89% voltage drop. He wants to use some #8 that he has (black), so that he only has to pay for the #6 (red) that we need for the install. Lately the inspectors have been cracking down on the 200.6 requirements of color coding. He got dinged on a job and had to pull out / replace a bunch of wire.

I say that he is insane, the wire he wants to use has a different voltage drop, different ampacity and he risks overheating it. Just save a few $$ on wire!

What have you been hit with?


  • BB.BB. Super Moderators, Administrators Posts: 32,027 admin
    Re: Crazy Ideas

    One poster here had an off grid solar install (battery based) where the electrican did the DC side (24 or 48 volt) exactly the same as he would doe a 120/240 VAC system. Without accounting for the fact that 1,500 Watts at 24 VDC uses a whole lot more current than 1,500 Watts at 120 VAC:

    1,500 Watt / 24 volts = 62.5 amps
    1,509 Watt / 120 volts = 12.5 amps

    There was also the time the NEC (national electric code) required a fuse between Safety Ground and the DC Battery Bank Ground bonding. Anytime there was over 1 amp of current flow (from a short circuit), it popped the fuse/breaker and caused the battery bank system/solar array to go from negative ground to positive ground--And they called it good (and still require this today).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Crazy Ideas

    as long as the color is right and the wire he uses meets all specs for the intended use, the extra losses by the use of the #8 probably won't do anything nasty to the wire losses in most cases. seeing it at .89% for the #6 the 1 lead for #8 will most likely up this into the 1.x% area which is still quite acceptable. there is no rule that the + and - wires must be the same gauge, but it makes it easier for most to stay with the same gauge.
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