# Diesel generator block heater circuit



## gpop (May 14, 2018)

pete25 said:


> Does the NEC require an engine block heater circuit for a generator be GFCI protected?


Does the NEC require an outside receptacle to be GFCI protected. (its a receptacle so it doesn't matter whats plugged into it)

Not sure what would happen if you hard wired the heater.


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## micromind (Aug 11, 2007)

If it does, I've violated it on every gen I've ever installed.........


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## Wirenuting (Sep 12, 2010)

Ever feel when a block heater goes bad?

It will make you wish it had been GFCI protected. 
It HERTZ!!


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## Awg-Dawg (Jan 23, 2007)

Sounds like a good place for an audible trip type.


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## 460 Delta (May 9, 2018)

It would likely be a violation, but with the genset solidly grounded there shouldn't be an issue. On r-mix trucks when a GFCI nuisance trips, well you have a truck that won't start for a few hours, with a genset you don't have that much time. When the power goes out you want it to crank a couple turns, go to 800 RPM for oil pressure then go full song in 10 sec or less. No time for resetting GFCI's and similar foolishness.


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## emtnut (Mar 1, 2015)

OK, i'll bite ... Gen outside ? Resi ? Commercial outside ? Industrial inside ?
*Plugged into an outlet ??????????*
5kW ? 500kW ?

Oh wait ... He's an engineer ... forget the details, we'll fix it once it's installed :biggrin:
I made a living once on extras !


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## Southeast Power (Jan 18, 2009)

We install a duplex GCFI with a bubble cover on every small, 200kw, gas or diesel unit we install to pass inspection. :wink:


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## gpop (May 14, 2018)

emtnut said:


> OK, i'll bite ... Gen outside ? Resi ? Commercial outside ? Industrial inside ?
> *Plugged into an outlet ??????????*
> 5kW ? 500kW ?
> 
> ...


Most diesels generators have a receptacle inside the enclosure that the heater plugs into. In Florida its no big deal if you get a rouge gfci trip but further north i can see forgetting to install one.


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## telsa (May 22, 2015)

For such units, we hard wire them... and bond them... the gen-set... something silly.

During service, the entire unit is cut-out via a safety switch.

The ever common NEMA3R GFCI receptacle is nearby when that happens.

I never use a scheme that requires techs to get their power from the unit they must work on. 

It's totally dead when they work on it.

It's my house philosophy. It's not in the NEC, of course.

I have to provide a nearby GFCI receptacle anyway -- so it's not as if I'm spending big money.


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## emtnut (Mar 1, 2015)

gpop said:


> Most diesels generators have a receptacle inside the enclosure that the heater plugs into. In Florida its no big deal if you get a rouge gfci trip but further north i can see forgetting to install one.


That's why I asked if resi-commercial-Industrial.

All the Industrial ones I've seen were hard-wired in the control panel.


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## gpop (May 14, 2018)

emtnut said:


> That's why I asked if resi-commercial-Industrial.
> 
> All the Industrial ones I've seen were hard-wired in the control panel.


Florida may be different as the heater is a option. The 30 plus industrial units at work all have plug in units (water heaters). All of our control panels are 12vdc or 24vdc so theirs no where to wire in a heater.


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## emtnut (Mar 1, 2015)

gpop said:


> Florida may be different as the heater is a option. The 30 plus industrial units at work all have plug in units (water heaters). All of our control panels are 12vdc or 24vdc so theirs no where to wire in a heater.


Interesting how various plants do things differently.

We always had some form of Scada control, with hand/off/auto switches etc... all were hard wired to 120V in the panel.


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## nrp3 (Jan 24, 2009)

The ten year or so old Eaton (Cat, Olympian, FG Wilson, etc) that I work on has a hardwired block heater that eventually ruined the terminal block it was attached to so I bypassed the block and just wirenutted into the harness. Most of the others I work on have receptacles for block, battery, oil panel warmers, etc.


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## Southeast Power (Jan 18, 2009)

I worked at a facility that has 6 1 meg Cats.
Everyone had a hard-wired jacket heater.
Every one of them had the paper instructions left folded up in the wiring compartment.
The paper dried out, caught fire, and burned every wire in the compartment.


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## nrp3 (Jan 24, 2009)

Southeast Power said:


> I worked at a facility that has 6 1 meg Cats.
> Everyone had a hard-wired jacket heater.
> Every one of them had the paper instructions left folded up in the wiring compartment.
> The paper dried out, caught fire, and burned every wire in the compartment.


Block heaters for those must be pretty massive. Moral of the story, don't leave instructions in with wiring... I guess?


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## Southeast Power (Jan 18, 2009)

nrp3 said:


> Block heaters for those must be pretty massive. Moral of the story, don't leave instructions in with wiring... I guess?


The heaters were the size of a coffee can. I can't remember if a circulating pump was built into them or not. 
It might sound unnecessary but, we like to keep them warm.


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## Kevin (Feb 14, 2017)

Southeast Power said:


> The heaters were the size of a coffee can. I can't remember if a circulating pump was built into them or not.
> 
> It might sound unnecessary but, we like to keep them warm.


Most likely there was a circulating pump for something that big.

Sent from my Samsung using Tapatalk


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## Southeast Power (Jan 18, 2009)

Kevin_Essiambre said:


> Most likely there was a circulating pump for something that big.
> 
> Sent from my Samsung using Tapatalk


I havent noticed a circulator on the heaters we have been plugging in, I just assumed they were mostly convection type. Somehow they manage to keep the engine warm.


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