Double Pole Electric Base Board with Single Pole Thermostat

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I believe 424.19 is the section to look at.

424.19(B) Heating Equipment Without Supplementary Overcurrent
Protection.
(1) Without Motor or with Motor Not over 1∕8 Horsepower.
For fixed electric space-heating equipment without a motor
rated over 1∕8 hp, the branch-circuit switch or circuit breaker
shall be permitted to serve as the disconnecting means where
the switch or circuit breaker is within sight from the heater or
is lockable in accordance with 110.25
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Yup if the stat only breaks one leg it doesn't qualify as the disconnecting means so you'll need one within sight (can be the panel where the circuit originates) or a locking device on the breaker that's not within sight.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
You can also get T-stat that breaks one line for control but opens both lines when set to off. Having an off position is the indicator of a T-stat that does so.
 

MAC702

Senior Member
Location
Clark County, NV
I've only done one line-voltage stat in recent memory. It had an off-position. It only broke one line no matter what it was doing. The other line didn't even pass through it.
 

MAC702

Senior Member
Location
Clark County, NV
I should clarify that it had an "off" position on the temperature dial, but not a separate on/off switch. It was a Honeywell. And it was rated 120/208/240/277.
 

romex jockey

Senior Member
Location
Vermont
Yup if the stat only breaks one leg it doesn't qualify as the disconnecting means so you'll need one within sight (can be the panel where the circuit originates) or a locking device on the breaker that's not within sight.
I'm curious if a locking panel door is compliant?

~RJ~
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Was this always this way? Or a recent change Infinity?

~RJ~
Here's the 2017 section:

110.25 Lockable Disconnecting Means. If a disconnecting
means is required to be lockable open elsewhere in this Code, it
shall be capable of being locked in the open position. The
provisions for locking shall remain in place with or without the
lock installed.
Exception: Locking provisions for a cord-and-plug connection shall not
be required to remain in place without the lock installed.
Here's the 2005 section:

424.19(B) Heating Equipment Without Supplementary Overcurrent Protection
(1) Without Motor or with Motor Not Over 1 / 8 Horsepower For fixed electric space-
heating equipment without a motor rated over 1 / 8 hp, the branch-circuit switch or circuit
breaker shall be permitted to serve as the disconnecting means where the switch or circuit
breaker
is within sight from the heater or is capable of being locked in the open position
 
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