# 15A switch on 20A circuit?



## MDShunk (Jan 7, 2007)

Switches are sized to the connected load they serve, and bear no relationship to the overcurrent protective device on the circuit.


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## shocking (Aug 24, 2007)

thank you! what if you dont know what the load will be?


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## MDShunk (Jan 7, 2007)

shocking said:


> thank you! what if you dont know what the load will be?


Then it would seem reasonable to size the swtich full size. Most normally, the load is known. After all, you did size the branch circuit itself by some means.


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## shocking (Aug 24, 2007)

i see. owner wanted 20A circuits for future use but not sure what for. might as well use 20.


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## MDShunk (Jan 7, 2007)

shocking said:


> i see. owner wanted 20A circuits for future use but not sure what for. might as well use 20.


Yeah, it's a no-brainer in that case. It's just a shame is all, since the 20 amp switches are more than twice as expensive, and they might not ever be needed at that capacity. 

It is common to see full size switches spec'd on commercial prints.


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## Speedy Petey (Jan 10, 2007)

shocking said:


> i see. owner wanted 20A circuits for future use but not sure what for. might as well use 20.


That's all well and good, but what are the switches controlling? Obviously not the whole circuit.


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## MDShunk (Jan 7, 2007)

You might talk the owner into letting you put in switch dummies (fillers for a switch cover plate) until such time as they're actually used for something.


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## shocking (Aug 24, 2007)

hes assuming on putting up track lighting, but not sure . some of them draw 20A. just wants the expandability is what he says.


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## MDShunk (Jan 7, 2007)

shocking said:


> hes assuming on putting up track lighting, but not sure . some of them draw 20A. just wants the expandability is what he says.


Give him what he wants, then. Sounds like he's all but begging you to install 20 amp switches.


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## shocking (Aug 24, 2007)

thanks guys! great forum too! before i go, what does the NEC require on this issue?


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## MDShunk (Jan 7, 2007)

shocking said:


> thanks guys! great forum too! before i go, what does the NEC require on this issue?


_*404.14 Rating and Use of Snap Switches. *Snap switches
shall be used within their ratings and as indicated in
404.14(A) through (D).
FPN No. 1: For switches on signs and outline lighting, see
600.6.
FPN No. 2: For switches controlling motors, see 430.83,
430.109, and 430.110.
*(A) Alternating Current General-Use Snap Switch.* A
form of general-use snap switch suitable only for use on ac
circuits for controlling the following:
(1) Resistive and inductive loads, including electricdischarge
lamps, not exceeding the ampere rating of the
switch at the voltage involved
(2) Tungsten-filament lamp loads not exceeding the ampere
rating of the switch at 120 volts
(3) Motor loads not exceeding 80 percent of the ampere
rating of the switch at its rated voltage
*(B) Alternating-Current or Direct-Current General-
Use Snap Switch.* A form of general-use snap switch suitable
for use on either ac or dc circuits for controlling the
following:
(1) Resistive loads not exceeding the ampere rating of the
switch at the voltage applied.
(2) Inductive loads not exceeding 50 percent of the ampere
rating of the switch at the applied voltage. Switches
rated in horsepower are suitable for controlling motor
loads within their rating at the voltage applied.
(3) Tungsten-filament lamp loads not exceeding the ampere
rating of the switch at the applied voltage if
T-rated.
*(C) CO/ALR Snap Switches. *Snap switches rated 20 amperes
or less directly connected to aluminum conductors
shall be listed and marked CO/ALR.
*(D) Alternating-Current Specific-Use Snap Switches
Rated for 347 Volts.* Snap switches rated 347 volts ac shall
be listed and shall be used only for controlling the following.
(1) Noninductive Loads. Noninductive loads other than
tungsten-filament lamps not exceeding the ampere and voltage
ratings of the switch.
(2) Inductive Loads. Inductive loads not exceeding the
ampere and voltage ratings of the switch. Where particular
load characteristics or limitations are specified as a condition
of the listing, those restrictions shall be observed regardless
of the ampere rating of the load.
The ampere rating of the switch shall not be less than
15 amperes at a voltage rating of 347 volts ac. Flush-type
snap switches rated 347 volts ac shall not be readily interchangeable
in box mounting with switches identified in
404.14(A) and (B).
*(E) Dimmer Switches. *General-use dimmer switches shall
be used only to control permanently installed incandescent
luminaires (lighting fixtures) unless listed for the control of
other loads and installed accordingly._


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