Reduced neutral to dryer

Status
Not open for further replies.
G

Galt

Senior Member
Location
Wis.
Occupation
master electrician and refrigeration service tech.
Say you are running conduit to a clothes dryer 2 black 10 AWG. 1 green 10 AWG. but you have no white 10ga. could you run a 12?
 
Look at it like this: you could get away with it on a clothes dryer since the motor and the timer combined rarely exceed more than 6 amps, but what would prevent someone from plugging in something that puts more than 20amps on the noodle? I know not likely to happen in a home, but you never know.
 
chadnodine said:
Why don't you use the green 10awg and phase it white? Then phase your #12 green? Then you are legal so to speak!
Click to expand...

Not legal, in general you cannot re-identify a green conductor.

It is a violation to use a green conductor as grounded or ungrounded conductor. There are some exceptions but not conduit supplying a dryer.

250.119 Identification of Equipment Grounding Conductors.
Unless required elsewhere in this Code, equipment
grounding conductors shall be permitted to be bare,
covered, or insulated. Individually covered or insulated
equipment grounding conductors shall have a continuous
outer finish that is either green or green with one or more
yellow stripes except as permitted in this section. Conductors
with insulation or individual covering that is green,
green with one or more yellow stripes, or otherwise identified
as permitted by this section shall not be used for ungrounded
or grounded circuit conductors.
Click to expand...
 
iwire said:
It looks to me like 210.19(A)(4) would allow this.
Click to expand...

This covers taps and fixture wire? I am not saying that you are wrong, just that I do not see a neutral conductor following tap rules.



(4) Other Loads. Branch-circuit conductors that supply
loads other than those specified in 210.2 and other than
cooking appliances as covered in 210.19(A)(3) shall have
an ampacity sufficient for the loads served and shall not be
smaller than 14 AWG.

Exception No. 1: Tap conductors shall have an ampacity
suffıcient for the load served. In addition, they shall have
an ampacity of not less than 15 for circuits rated less
than 40 amperes and not less than 20 for circuits rated
at 40 or 50 amperes and only where these tap conductors
supply any of the following loads:

(a) Individual lampholders or luminaires with taps extending
not longer than 450 mm (18 in.) beyond any portion
of the lampholder or luminaire.

(b) A luminaire having tap conductors as provided in
410.117.

(c) Individual outlets, other than receptacle outlets,
with taps not over 450 mm (18 in.) long.

(d) Infrared lamp industrial heating appliances.

(e) Nonheating leads of deicing and snow-melting
cables and mats.
Exception No. 2: Fixture wires and flexible cords shall be
permitted to be smaller than 14 AWG as permitted by
240.5.
Click to expand...
 
mbrooke said:
This covers taps and fixture wire? I am not saying that you are wrong, just that I do not see a neutral conductor following tap rules.
Click to expand...
I considered the possibility prior to my first post. But in reconsidering...

The general rule of 210.19(A)(4) looks quite tempting, but you can't use #12 on a greater than 20A circuit per 240.4(D)(5)... as a normal circuit conductor. As a tap conductor, perhaps 210.19(A)(4) Exception No.1 item (c). I get two different interpretations when reading that item. Is it saying individual receptacle outlets are okay... or not okay?
 
Also wanted to throw this out there. A dryer is a motor operated appliance, so 240.4(G) overrules 240.4(D)(5) and sends us to 422 Part II. Nothing in Part II specifically allows a reduced neutral, so can we fall back on 422.3 which states Article 430 shall apply for a motor-operated appliance...???
 
Last edited:
480sparky said:
.....such as, what?
Click to expand...
who knows what, you never know (which is what the NEC writes code for). shouldn't all CCC's be sized to the receptacle's amp rating?

7080333__85990.1450869003.500.750.jpg
 
Last edited:
480sparky said:
.....such as, what?
Click to expand...

Good question.


My best guess would be a kiln (or grow lights if you really wanted to go out there) with a 208 volt supply. There are appliances out there that modulate high/low by toggling one side of the heating elements between the noodle and L2; or have 2 120 volt elements connected L1-N and L2-N.


http://www.paragonweb.com/4-Way_Rotary_Switch.cfm


IM55_4way_Rotary.jpg
 
Last edited:
Smart $ said:
I considered the possibility prior to my first post. But in reconsidering...

The general rule of 210.19(A)(4) looks quite tempting, but you can't use #12 on a greater than 20A circuit per 240.4(D)(5)... as a normal circuit conductor. As a tap conductor, perhaps 210.19(A)(4) Exception No.1 item (c). I get two different interpretations when reading that item. Is it saying individual receptacle outlets are okay... or not okay?
Click to expand...

Well, IMHO no since its saying other than receptacle outlets. A receptacle is an outlet, but not all outlets are receptacles. Here is the definition of outlet:


Outlet. A point on the wiring system at which current is
taken to supply utilization equipment.
Click to expand...

I could be very wrong though.
 
mbrooke said:
Well, IMHO no since its saying other than receptacle outlets. A receptacle is an outlet, but not all outlets are receptacles. Here is the definition of outlet:
I could be very wrong though.
Click to expand...
your view of outlet is correct. but perhaps "receptacles" are excluded by that 18" verbiage?

but
210.19 in 2017 nec
(b) The minimum branch-circuit conductor size shall have an allowable ampacity not less than the maximum load to be served after the application of any adjustment or correction factors.
Click to expand...


where exactly would you be getting a "load" # for a dryer ??

GE dryer i lookup simply says "25A", thus all CCC's that has 25A min ampacity after all adjustments, which puts it back to #10.
 
Last edited:
FionaZuppa said:
your view of outlet is correct.

but
210.19 in 2017 nec


where exactly would you be getting a "load" # for a dryer ??

GE dryer i lookup simply says "25A", thus all CCC's that has 25A min ampacity after all adjustments, which puts it back to #10.[/FONT][/COLOR]
Click to expand...



My understanding is the NEC lets you do load calcs without the nameplate known, but I am still unsure how the neutral factors into that.


I think the reason why we might be having a hard time with this is because the code actually lets you run a smaller circuit then the receptacle rating when its a single dedicated receptacle. Ie, its not uncommon to find a NEMA 14-50 range outlet fed by a 40amp circuit.
 
Status
Not open for further replies.
Top