6/3 NM cable
- Thread starter nizak
- Start date
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes if the calculated load is 55 amps or less.
Thank you.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Keep in mind that calculated load will be 125% of continuous load. So you are looking at max continuous load of 44 amps that can be supplied or 55 amps of non continuous load. Or 125% of continuous plus 100% of non continuous can not be more than 55.
Motors or air conditioning needs to follow art 430 or 440 and you possibly could have even higher OCPD in those cases, but MCA or 125% of FLA still would need to be no more than 55.
They should bring back 5 AWG like a 5/2 NM-B it would be perfect for EV's as it would be about 63 amps, there is 5AWG in the old codes.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Didn't that end about 1943?
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
I agree 100%.
Actually get rid of NM cable entirely. No reason to have a cable that has unknown conductor insulation, can't be installed in wet locations and is limited 60C.
The only real difference between NM and SE is the paper fillers and the unmarked conductors. Get rid of the paper and use THHN/THWN-2 insulation on the conductors.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
A men brother
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
Actually that might get rid of the handyman, DIY from the electrical field. Haven't seen one that can bend pipe.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
I think of it another way. Isn't NM although the cable assembly is rated for 60C max the wires are actually THHN rated at 90C although unmarked?
I mean if SE cable is allowed to run 75C why is NM not allowed to run at 75C? SE is usually XHHW and NM is THHN both 90C conductors although NM wires are unmarked
Also, if someone knows when was NM cable restricted to 60C? It was commonplace to use it to feed HVAC equipment that called for 75C wire using the ampacity charts for motors and HVAC equipment that allowed over/fuse/breaker MCA & MOCP?
I mean if SE cable is allowed to run 75C why is NM not allowed to run at 75C? SE is usually XHHW and NM is THHN both 90C conductors although NM wires are unmarked
Also, if someone knows when was NM cable restricted to 60C? It was commonplace to use it to feed HVAC equipment that called for 75C wire using the ampacity charts for motors and HVAC equipment that allowed over/fuse/breaker MCA & MOCP?
- Location
- Illinois
- Occupation
- retired electrician
UL 719 requires that the conductors in NM-B have the properties required for THHN conductors.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
But they're not required to BE thhn, so that results in all sorts of problems and hassles. Why not just make them actually THHN and make everything simpler for everybody?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Now why would you apply logic to this stupidity?
Change the required conductors to actually be THHN and get rid of this stupid 60° C limit.
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
We all know the cable manufactures are not making a special conductor insulation just for NM cables that has the same properties as THHN.
They are using the exact same wire they sell us on reals marked THHN/THWN, they just don't run it through the marking machine.
They are using the exact same wire they sell us on reals marked THHN/THWN, they just don't run it through the marking machine.
NM is supposed to be the bargain basement of wire for residential work, installed in thermal insulated walls.
Somebody spent allot of time effort and money lobbying UL to get a menu of insulation options that save the manufacturers money.
To me #6 and #8 NM more closely resemble TW, it has those thicker strands that TW has.
It has no resemblance to THWN-2 to me other than the nylon jacket.
In this video you can see how NM is made they insulate the wire right at the cable plant, it may be the same PVC pellets but I'd wager that THWN-2 is a different mix of PVC and finer stranding that costs more. I agree with ordering #6 copper SE cable for EVSE installs.
Somebody spent allot of time effort and money lobbying UL to get a menu of insulation options that save the manufacturers money.
To me #6 and #8 NM more closely resemble TW, it has those thicker strands that TW has.
It has no resemblance to THWN-2 to me other than the nylon jacket.
In this video you can see how NM is made they insulate the wire right at the cable plant, it may be the same PVC pellets but I'd wager that THWN-2 is a different mix of PVC and finer stranding that costs more. I agree with ordering #6 copper SE cable for EVSE installs.
- Location
- Illinois
- Occupation
- retired electrician
Conductors having the properties of TW are permitted, but not for NM-B as they are not 90°C conductors, and 90°C conductors are required for NM-B. The stranding in the conductor has nothing to do with the insulation of the conductor.
Rick 0920
Senior Member
- Location
- Jacksonville, FL
- Occupation
- Electrical Instructor
They do make a #6 SEU cable with 2 hots and a wrapping stranded grounding conductor. This is rated as a 75 C. conductor and if all of your connected terminations are listed for 75C your ampacity is higher.
I was responding to the comment that "They are using the exact same wire they sell us on reals marked THHN/THWN," if they were just using the same #6 THWN/THHN at the factory to make #6NM I'd expect the stranding to be the same.