Line of sight rule for heaters?

[Twophase]

I've heard over the years that the NEC requires a disconnecting means to be in line of sight of the powered equipment. I'm confused as to how this applies to heaters.

Does the line of sight rule also apply to heaters? For example, a tank heater (does the fluid type make a difference?) or pipe heat tracing in an industrial setting (the disconnecting means is lockable, or a breaker, but not in line of sight of the heating elements). How about space heaters (resistance type by with a fan = motor load?)

I've read the relevant NEC sections and am inclined to think that it isn't required, but I'm confused since many people mention the "line of sight rule"

Any guidance is appreciated.

 

[Dennis Alwon]

For baseboard type heaters you can use a controller to disconnect the heat. So, if you have a 240v heater and a DP wall t-stat that is suitable as a disconnect.

424.19 Disconnecting Means. Means shall be provided to
simultaneously disconnect the heater, motor controller(s), and
supplementary overcurrent protective device(s) of all fixed
electric space-heating equipment from all ungrounded conductors.
Where heating equipment is supplied by more than one
source, feeder, or branch circuit, the disconnecting means shall
be grouped and identified as having multiple disconnecting
means. Each disconnecting means shall simultaneously disconnect
all ungrounded conductors that it controls. The disconnecting
means specified in 424.19(A) and (B) shall have an
ampere rating not less than 125 percent of the total load of the
motors and the heaters and shall be lockable in accordance
with 110.25.

424.20 Thermostatically Controlled Switching Devices.
(A) Serving as Both Controllers and Disconnecting Means.
Thermostatically controlled switching devices and combination
thermostats and manually controlled switches shall be permitted
to serve as both controllers and disconnecting means,
provided they meet all of the following conditions:
(1) Provided with a marked “off” position
(2) Directly open all ungrounded conductors when manually
placed in the “off” position
(3) Designed so that the circuit cannot be energized automatically
after the device has been manually placed in the
“off” position
(4) Located as specified in 424.19
(B) Thermostats That Do Not Directly Interrupt All Ungrounded
Conductors. Thermostats that do not directly interrupt all
ungrounded conductors and thermostats that operate remotecontrol
circuits shall not be required to meet the requirements
of 424.20(A). These devices shall not be permitted as the
disconnecting means.

 

[Dennis Alwon]

Here is Pipeline.. This allows a breaker lock in lieu of a disconnect in sight.

427.55 Disconnecting Means.
(A) Switch or Circuit Breaker. Means shall be provided to
simultaneously disconnect all fixed electric pipeline or vessel
heating equipment from all ungrounded conductors. The
branch-circuit switch or circuit breaker, where readily accessible
to the user of the equipment, shall be permitted to serve as
the disconnecting means. The disconnecting means shall be of
the indicating type and shall be capable of being locked in the
open (off) position. The disconnecting means shall be installed
in accordance with 110.25.

 

[Twophase]

Here is Pipeline.. This allows a breaker lock in lieu of a disconnect in sight.

Thanks. I read this earlier and was thinking the same thing, but then the question was raised - does the breaker (the panelboard, or enclosure) need to be in sight of the disconnect?

Also, what if there is an intermediate device (controller, thermostat, etc) between the breaker and vessel heater/pipe heat tracing (breaker to controller/thermostat to vessel heater/heat trace). Can I treat the heating element and the controller /thermostat as a "group"?

 

[tom baker]

Thanks. I read this earlier and was thinking the same thing, but then the question was raised - does the breaker (the panelboard, or enclosure) need to be in sight of the disconnect?

Also, what if there is an intermediate device (controller, thermostat, etc) between the breaker and vessel heater/pipe heat tracing (breaker to controller/thermostat to vessel heater/heat trace). Can I treat the heating element and the controller /thermostat as a "group"?

Several of the code sections cited list "The disconnecting means shall be installed in accordance with 110.25".
Definitions are always a good place to start...

 

[Twophase]

Several of the code sections cited list "The disconnecting means shall be installed in accordance with 110.25".
Definitions are always a good place to start...

110.25 refers to lockable disconnecting means (must be able to be locked in the open position)

Is there something I'm missing? Is a lockable disconnecting means an exception to the line of sight rule? Sorry, a bit new to these parts of the NEC

 

[augie47]

Generally speaking, "in sight from" requirement for a disconnecting means occurs when motors are part of the equipment.
You actually need to check each relevant section but "in sight from" will be specified where required.

 

[GoldDigger]

But generally when not "in sight" the disconnecting means must be lockable instead, and the two options are both mentioned in code section.

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