You are watching: What size ground wire for 60 amp
How walk an undersized grounding conductor work? take an 8-2 NM cable because that example, that only uses a #10 ground. Why doesn"t it require a complete size ground? They used to make smaller sized gauge NM with undersized floor (14-2 v #16 ground), however that"s not enabled anymore. Why does it work with higher ampacity circuits?Thanks
The more I discover the less I seem to know......
that is two various situations. Conductor ampacity is sized off 310.16 i beg your pardon is usually how numerous amps that dimension conductor can carry without hurting the insulation. A grounding conductor is not an alleged to bring current so the is size differently.
The an ext I find out the less I seem to know......
The grounding conductor walk not carry current during normal conditions.It"s minimum size is dictated by it"s capacity to clean a fault.
So it"s for sure to have a #10 lug 60 amps because that a really short time. Or is that over simplifying it? Isn"t fault present sometimes well over that?
It needs to do through heat and also time.The 10 AWG EGC will trip a 60 amp breaker faster than the 10 AWG heats up to dangerous levels.Keep in mind the present rating a of wire is always around heat, a 14 AWG copper will certainly carry nearly 200 amps before the copper melts yet of course the insulation would be long gone by the point.Check out Table 310.21 it shows the ampacity of ceiling 8 AWG together 98 amps but the conductor temperature could be close come 176 F.
So it"s safe to have a #10 carry 60 amps because that a really short time. Or is the over simple it? Isn"t fault present sometimes well over that?
If a 60 amp circuit has a fault to the EGC the current during that fault will certainly be in the 100s the amps till the breaker opens so also the circuit conductors will be "overloaded" because that a short time.
Ok. This is simply in general for circuits right? arent there special rules for warm tubs and so on that require full size ground? or maybe I"m think that it needs to be insulated?
The NEC go not need a full size EGC for hot tubs however if the hot bath tub instructions require it (and I have actually read part do) than 110.3(B) would certainly kick in and also you would have to follow the institutions.
the function of a large ground wire on pool stuff is an ext for prevention of physical damage, i believe. More tough to kick a #8 and also have it rest or come loose.
The specs on the MRI machines we installed called for two grounding conductors the very same size as phase conductors. One isolated and also one equipment ground. We saw terminate and the equipment only had actually one place to land. So, one came out.
The grounded conductor must be sized the exact same as the ungrounded "hot" conductors in many systems to have the ability to potentualy lug the maximim unbalanced load.......
All copper conductors are defended for their insulation. #10 copper will certainly lug 60 amps v no problem but that level of present will, end time, deteriorate the insulation . In the occasion of a brief circuit the "current" will only be there because that a quick time and the reason of the heat will be unable to do if all is wired correctly.
The grounded conductor need to be sized the same as the ungrounded "hot" conductors in many systems to have the ability to potentualy carry the maximim unbalanced load.......
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