# Safety Switch / Disconnect for Generator Block Heater



## jar546 (Nov 20, 2018)

If a generator has a block heater fed by a circuit breaker within a panel not within site of the generator, is it required to have a disconnect/safety switch?  If so, what is the NEC code that you would cite?
If no then state so.


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## north star (Nov 21, 2018)

*@ ~ @*

No, not required, but the circuit breaker must be in a
panel capable of being locked when the circuit
breaker is turned off.......If the circuit breaker is not
in a lockable panel, then there must be a disconnect
means capable of being locked in the open position
[ * RE:*  `17 NEC, Article 445.18(A)  ].

*@ ~ @*


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## chris kennedy (Nov 21, 2018)

427.55(A)
Must be readily accessible.


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## ICE (Nov 21, 2018)

north star said:


> *@ ~ @*
> 
> No, not required, but the circuit breaker must be in a
> panel capable of being locked when the circuit
> ...


_445.18 Disconnecting Means Required for Generators. 

Generators shall be equipped with a disconnect(s), lockable in the open position by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator except where the following conditions apply: 
_
I disagree with the code section in that it is about the generator and not a block heater.


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## ICE (Nov 21, 2018)

chris kennedy said:


> 427.55(A)
> Must be readily accessible.



_427.1 Scope. The requirements of this article shall apply to electrically energized heating systems and the installation of these systems used with *pipelines or vessels* or both. 

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 (off) open position.

Pipeline. A length of pipe including pumps, valves, flanges, control devices, strainers, and/or similar equipment for conveying fluids.

Vessel. A container such as a barrel, drum, or tank for holding fluids or other material. 
_
I disagree with the code section in that it is about pipelines and vessels and the topic of the thread is an engine block heater.
_



_


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## ICE (Nov 21, 2018)

The block heaters that I have used are a probe that is stuck into the oil fill tube.  Cord and plug they were.  I assume that Jeff is talking about something more than that.

_422.1 Scope. This article covers electrical appliances used in any occupancy.

422.31 Disconnection of Permanently Connected Appliances.

(A) Rated at Not over 300 Volt-Amperes or 1⁄8 Horsepower. For permanently connected appliances rated at not over 300 volt-amperes or 1⁄8 hp, the branch-circuit overcurrent device shall be permitted to serve as the disconnecting means.

(B) Appliances Rated over 300 Volt-Amperes. For permanently connected appliances rated over 300 volt- amperes, 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 appliance or is lockable in accordance with 110.25._


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## RJJ (Nov 21, 2018)

I agree with 422.31(B). It is very similar to disconnects for signs.


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## chris kennedy (Nov 21, 2018)

Block heaters on the big gennys Jeff is doing are connected by pipes. And wouldn’t a radiator be a vessel?


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## RJJ (Nov 21, 2018)

I would say yes to a radiator being a vessel. Most block heaters are usually an element in one of the freeze plugs.


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## ICE (Nov 21, 2018)

chris kennedy said:


> Block heaters on the big gennys Jeff is doing are connected by pipes. And wouldn’t a radiator be a vessel?


Odds are pretty good that I don't know what I am talking about here.  I didn't envision a radiator heater.  I could see that being a vessel per the definition.  Either way the code will require a disconnect and an appliance it is not.


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## steveray (Nov 21, 2018)

chris kennedy said:


> Block heaters on the big gennys Jeff is doing are connected by pipes. And wouldn’t a radiator be a vessel?



A building is connected by pipes......I'd have to really look into vessel as that is not really a "container" IMO....I'd be more apt to go with appliance 422.31B, but no one posted that definition....


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## chris kennedy (Nov 21, 2018)

I agree 422 can be enforced here also.
I just like to throw around obscure code articles.


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## ICE (Nov 21, 2018)

_Appliance. Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air-conditioning, food mixing, deep frying, and so forth. _

I'm not seeing a block heater as an appliance if it is built into a radiator.


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## jar546 (Nov 21, 2018)

_.....coming online at an engine’s rated RPMs and assuming a full load within the 10-second window specified in NFPA standard 110 and Canadian CSA 282 requires maintaining engine temperature between 100°F to 120°F. Bass also maintains that, in addition to easier starts, block heaters save engine warmup time and help reduce fuel, plus engine wear—90% of which he attributes to low water jacket temperature._


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## jar546 (Nov 21, 2018)

Wow, lots of changes to 445.18 in 2014 and 2017.  Either way the changes in 2014 require disconnects that are lockable in the open position, not just for the generator output but for all associated ungrounded conductors.

Therefore, not only does a block heater require a lockable disconnect but so does the battery charger circuit (most new generators have built in batter chargers and no longer have DC coming in from an outside charging circuit.

The writing is on the wall.


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## RJJ (Nov 23, 2018)

Most block heaters are built into the Block, not the radiator. There is no water circulation when the engine is not running. Also, the majority of these units run on fuel, not gasoline. When the engine temp is below operating temp. the unit consumes larger amount of fuel while the glow plugs start combustion.


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