GFPE for Floor Heat Tape - Freezers

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scott thompson

Senior Member
GFPE for Floor Heat Tape - Freezers

Hello all,

It's been a long time since my last post, so let me first say I hope everyone is doing great!!!
:)

I am 100% "In The Office" now, and only see Job sites when doing a job walk, performing Project Management tasks (I know, i am a P.M.... don't make too much fun of me...), client meetings (AKA "Yawning Festivals"... hee hee hee), and the occasional Inspection.
It's taking some getting used to, but my field days are long gone!

Anyway, to the questions at hand:

I have a question regarding the installation of Heat Tape in Concrete Floors of Freezers + Coolers, which will maintain an ambient temperature between 0? C and -30? C; and the need for GFPE devices.
additional locations with the Self regulated Heat Tape will be Man Doors, Lift Doors and Condensation Drain Lines.

Referencing NEC (2002 version) Articles:
* 426: Fixed Outdoor electric De-icing and Snow Melting Equipment,
* 427: Fixed electric Heating Equipment for Pipelines and Vessels.

Basics:
The Floor Heat tape is inserted into PVC conduit, which is installed under the Concrete slab (set prior to pour). The purpose for this Heat Tape is to reduce the issues of Permafrost buildup under the slab, and maintain constant temperature within the slab, so as to reduce chances for cracking the slab.
It is something that needs to be active continuously.

Heat Tape for Doors ("Door Heat"), is to reduce issues with expansion / contraction of doors, which makes them un-openable.

Condensate Drain line Heat Tape - as the name suggests, keeps the condensed water in the Condensate Drain line from freezing up.

Now to the quoted articles:

Some Inspectors are quoting Article 426 with corrections to install "GFCI's", not GFPE.
Others are quoting either / both Article 426 and 427, again referencing the use of "GFCI's", not GFPE.

I mentioned the differences in Ground Fault Protection (plus the fact that the articles do not apply, except for the Drain Heat), only to get shot down with "Protection for Personnel" (not mentioned in the articles).

Problem with using any leakage detection with a trip threshold of upto 6ma, is some of the Heat Tape strips are long, and will eventually drain >6ma into the bonded sheath cover, thereby tripping a 6ma leakage sensing device (GFCI).

GFPE devices with leakage thresholds >/= 30ma, do not trip under normal conditions.
Only problem is sometimes it's difficult to get GFPE breakers for certain Panelboards.

My queries are:

1: Do these situations require GFPE?
2: Do they require GFCI (protection for personnel)?
3: Is there any type of "Stand-Alone" GFPE, for those situations where there are no GFPE breakers made, or readily available?

Looking forward to your comments!

Scott

x-posted with ECN...
 
I do not see the connection between the refrigeration equipment and the GFI protection.

I would look at article 424.44(G). It only requires GFCI protection when cables are installed in bathroom floors and in hydromassage bathtub locations.

I have never seen a factory system for heat in the floor in a bathroom not come with GFCI protection. If the manufacturer does not require it then I don't see the issue as I cannot see where the NEC requires it.
 
I have been involved with large freezers for past 3 years and never seen one gfci.Will be doing my first one with floor heat next week (-20).Not saying an inspector could not find a rule but till he does i wont use them.To me a freezer is simply a room with AC on steriods
 
It is my opinion that the underslab installation is covered by Article 426 based on the scope statement which is a lot more inclusive than the title of the article. That being the case 426.28 applies and GFP is required. I agree that the use of GFCI is not required and would often result in a trip as the normal leakage current often will exceed 5 mA.
On a side note, I would think that a metal raceway would be more effective as far a heat transfer than the PVC raceway. I even worked on one where a glycol solution was put in the metal piping along with the heat tape to increase the heat transfer. That was for some slide gates on a dam project. I have also been told that mineral oil is also used for this purpose.
As far as stand alone protection, Tyco Thermal has a heat trace controller Digitrace 910 that provides GFP and other protections and alarms.
Don
 
Don:
Respectfully, I have to disagree with your opinion. The word "outdoor" is mentioned:
426.28 Equipment Protection
Ground-fault protection of equipment shall be provided for fixed outdoor electric deicing and snow-melting equipment, except for equipment that employs mineral-insulated, metal-sheathed cable embedded in a noncombustible medium.

It is also mentioned:
ARTICLE 426 Fixed Outdoor Electric Deicing and Snow-Melting Equipment

One thing I didn't note in Scott's post was is there any GF mentioned within the job spec, or within the mfg install instructions

John
 
John,
It is my opinion that the wording in 426.28 refects the title of the Article, but the scope of the Article far exceeds the title and the rule in 426.28 applies to all heating devices covered by the scope of the Article.
Don
 
just to make active in my profile..i need some research time as I have never used ground fault protection on under slab heat..Can You tell us the brand of cable you are using? gotta go on call..
 
LOL..I am now really curious this is heating cable under the floor of an indoor structure most likely a commercial or industrial situation..No where do I know off does the heating cable need to be connected to GFPE or GFCI equipement..So correct me if I am wrong..I think the real issue is controlling the temp of the earth so it does not cause damage to the expensive freezer system..I would assume we are talking about either a commercial freezer operation or an industrial freezer system..I guess I would off peak electrical to supplement a hot water under ground system..I would think on this type of system you would want to excavate down about 4 ft and create a controlled system..Yet sounds like it is already finished and the controversy is in the over current devices..
 
Thanks to everyone who replied.

These projects are typically Design / Build, and we provide most specifications.

The brand of Heat Tape we commonly use is from Nelson.

I will post some more later on, as I need to make a visual check for pinholes on the back of my Eyelids...
:)

Thanks once again to everyone!

Scott
 
I am also having a problem with installation of the heat trace cable "Manufactured by Nelson" that requiered to be on GFPE. I did call Hubbell and Leviton to purchase the 30 MA trip device and they both told me they are not manufacturing those devices.
My solution to install 5 ma device but I have a problem with faulse tripping.
Any ideas?
 
scott thompson said:
Problem with using any leakage detection with a trip threshold of upto 6ma, is some of the Heat Tape strips are long, and will eventually drain >6ma into the bonded sheath cover, thereby tripping a 6ma leakage sensing device (GFCI).

GFPE devices with leakage thresholds >/= 30ma, do not trip under normal conditions.
Only problem is sometimes it's difficult to get GFPE breakers for certain Panelboards.

"GFPE devices with leakage thresholds >/= 30ma, do not trip under normal conditions"

I was under the impression that GFPE is variable and must be set according to the requirements of the specific install. . Are some GFPE breakers made with a single unchangeable trip value and others have a variable setting ?

David
 
David,
I have never seen a ground fault protection breaker with an adjustable trip. I am only talking about the type of breaker that you would use for heat trace circuits.
Don
 
don_resqcapt19 said:
David,
I have never seen a ground fault protection breaker with an adjustable trip. I am only talking about the type of breaker that you would use for heat trace circuits.
Don

So the main service GFPE [such as required by 230.95] is adjustable and individual circuit breakers [such as required by 426.28] are a set single value ?
 
I view gfci for freezers heat system as not only not required but could cause damage if they trip and not noticed fast.I did not use any on my last freezer job and it had floor ,drain,door heaters.
 
David,
So the main service GFPE [such as required by 230.95] is adjustable and individual circuit breakers [such as required by 426.28] are a set single value ?
Yes...at least for all that I have ever seen.
 
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