You are watching: What size ground wire for 60 amp sub panel
How walk an undersized grounding conductor work? take an 8-2 NM cable because that example, that only offers a #10 ground. Why doesn"t it need a complete size ground? They provided to make smaller sized gauge NM v undersized floor (14-2 v #16 ground), but that"s not allowed anymore. Why does it occupational with greater ampacity circuits?Thanks
The more I discover the much less I seem to know......
that is two various situations. Conductor ampacity is sized off 310.16 i m sorry is usually how plenty of amps that size conductor can lug without hurting the insulation. A ground connection conductor is not claimed to carry current so the is sized differently.
The more I discover the much less I seem come know......
The grounding conductor walk not bring current during normal conditions.It"s minimum dimension is dictated by it"s capability to clean a fault.
So it"s safe to have actually a #10 carry 60 amps because that a very short time. Or is that over simplifying it? Isn"t fault current sometimes well over that?
It has to do v heat and time.The 10 AWG EGC will expedition a 60 amp breaker quicker than the 10 AWG heats as much as dangerous levels.Keep in mental the present rating a of cable is always about heat, a 14 AWG copper will carry virtually 200 amps before the copper melts however of course the insulation would be long gone by the point.Check the end Table 310.21 it mirrors the ampacity of bare 8 AWG together 98 amps but the conductor temperature could be close to 176 F.
So it"s for sure to have actually a #10 bring 60 amps for a very short time. Or is that over simple it? Isn"t fault present sometimes well above that?
If a 60 amp circuit has actually a fault to the EGC the present during that fault will certainly be in the 100s the amps till the breaker opens up so even the circuit conductors will certainly be "overloaded" because that a short time.
Ok. This is simply in basic for circuits right? arent there unique rules for warm tubs etc that require complete size ground? or maybe I"m think that it needs to be insulated?
The NEC does not call for a full size EGC for warm tubs yet if the hot bath tub instructions need it (and I have actually read some do) 보다 110.3(B) would kick in and you would have to follow the institutions.
the function of a big ground cable on swimming pool stuff is more for avoidance of physics damage, ns believe. More tough to absent a #8 and also have it break or come loose.
The specs ~ above the MRI machines we installed dubbed for two grounding conductors the same size as phase conductors. One isolated and one tools ground. We visited terminate and also the equipment only had actually one place to land. So, one come out.
The base conductor must be sized the same as the ungrounded "hot" conductors in many systems to have the ability to potentualy carry the maximim unbalanced load.......
All copper conductors are defended for your insulation. #10 copper will certainly certainly lug 60 amps v no problem however that level of existing will, end time, compromise the insulation . In the event of a quick circuit the "current" will just be there because that a brief time and also the cause of the warmth will be unable to do if all is wired correctly.
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The grounded conductor need to be sized the very same as the ungrounded "hot" conductors in most systems to be able to potentualy carry the maximim unbalanced load.......
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