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Old 05-15-2012, 01:24 PM   #1
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GFEP Protection for Heat-Trace roof cables?


Hi there once again electrical Gurus. So I live in New England>NorthEast region. Our winters are usually real brutal. However, this past winter was mild and we received less than 4" of snow as compared to the winter before of 60". Anyway, The 2010-2011 season, we had massive ice damns as did 80% of the people in our area. I'm installing some Heat-Trace de-icing cables. Here's the breakdown:

13PK08W1-100ft / 120v / 13 watts per ft / 10.8 amps @ 32F
13PK08W1-75ft / 120v / 13 watts per ft / 8.1 amps @ 32F
Total Amperage = 18.9 amps / 120v @ 32F

National Electric Code:
-Total load must only be 80% of breaker capacity (Installing 30 amp single pole 120v breaker)
- Outside Equipment Protection must have a minimum 30ma protection (GFPE)
- 5ma protection (GFCI) might be too sensitive and will trip on the in-rush current during start up.

So I'm planning to install a switched outlet to a 2-pole switch I can control from inside. I'm using a 30A GFPE breaker for my panel which runs about $150. Using size 10-2 wire.

My Question:
If I'm using a GFPE breaker, can I use a standard receptacle? Also, do GFPE's have a neutral? I can't seem to find a GFPE receptacle so I'm hoping a standard will work. I'm not familiar with code on this but want to make sure I meet it. I will say that the receptacle/outlet will be installed under the 2 foot Eve of my house and upside down where water shouldn't penetrate it.

Help me out.
I appreciate it guys and girls.

~S


Last edited by Skelleyman; 05-15-2012 at 01:26 PM.
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Old 05-16-2012, 12:13 PM   #2
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GFEP Protection for Heat-Trace roof cables?


I don't know why a gfci would trip based on inrush current. They are designed to look at differential current from hot to neutral line. They trip if imbalance more than 5mA. By definition inrush current would be matched on both lines except if there was a ground fault. That is the only leakage path that would trip gfci.

I would try a $10 gfci before a $150 "muted" gfci. A simple resistor change in a gfci and they charge 15x the price?!!!!!

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Old 05-16-2012, 01:54 PM   #3
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GFEP Protection for Heat-Trace roof cables?


Using a two pole 250v GFCI breaker for 125v loads may cause the breaker to trip since it senses an impalance of the load.
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Old 05-16-2012, 02:03 PM   #4
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GFEP Protection for Heat-Trace roof cables?


With 12-3 you could run a MWBC and two 20 amp blank front GFCI's then go outside to your receptacles with in use covers to plug in the deicing cable.
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Old 05-16-2012, 05:23 PM   #5
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GFEP Protection for Heat-Trace roof cables?


the gfci doesn't trip from the inrush current. I would imagine it's due to the properties of heat trace cable. As the cable heats up it's resistance would increase resulting in a loss big enough to trip a GFCI.
I would assume and this is mostly guess work the you would be able to use a regular receptacle due to the fact that the breaker is the protection. Following the same rules as a gfci, if the breaker is gfci then the plug may be regular. The grey area is if the inspector will consider it as a non use plug. If he doesn't then by code you need to have gfci protection as it's an outdoor plug and in that case would have to hardwire the heat trace directly to the GFEP circuit.

GFEP breakers do have a neutrals as well.
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Old 05-17-2012, 08:32 AM   #6
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GFEP Protection for Heat-Trace roof cables?


Quote:
Originally Posted by andrew79
the gfci doesn't trip from the inrush current. I would imagine it's due to the properties of heat trace cable. As the cable heats up it's resistance would increase resulting in a loss big enough to trip a GFCI.....

It doesn't trip due to heating properties of cable. Sure the resistance will change some as it warms but that won't trip a ground fault circuit. The only thing to trip this device is a leakage current to ground such that the feed lines are unbalanced. This could be a break in the insulation and a moisture path to ground or some unsealed and wet junction points. All cable has some leakage characteristics and if the run is long enough and in a conductive spot (ie wet) then is can leak to ground and trip GF detector. I am sure this is why some go with GFEP devices to allow some level of leakage but to not trip the safety circuit. That said a GFCI and a well planned install seems a whole lot less expensive.
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Old 05-17-2012, 12:38 PM   #7
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GFEP Protection for Heat-Trace roof cables?


Heating cable tends to trip GFCI's due to capacitive leakage, just like long runs of buried or submersible cable. Even with the insulation perfectly intact, some current will be coupled to the wet conductive surroundings. If the run is not too long the GFCI may hold, but more than 5mA leakage is expected and normal for a fully loaded heating cable circuit. This is why GFPE is widely used for heating cable.
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Old 05-17-2012, 01:50 PM   #8
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GFEP Protection for Heat-Trace roof cables?


So what should I do?

These trace cables come with 36" of slack cord to standard 3 prong 120v that need to plug into something. However, the engineer is telling me the GFCI might be too sensative and to use GFEP. His words exactly "I have had installs with GFCIs, but that is not the most ideal way to install SR cable. "

These are plug in type, so I can't wire them directly to the breaker. He also said a switch in between would be the way to go (a switched outlet). So I can get the Single Pole 30A GFEP breaker, a weatherproof box and a standard receptacle. This doesn't elimate electrocution but protects the equipment. I don't know. I'm confused.
Thanks,
~S
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Old 05-17-2012, 02:09 PM   #9
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GFEP Protection for Heat-Trace roof cables?


Check with the manufacturer to see if the cables could be hardwired. If they can, you can eliminate the GFI protection.
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Old 05-17-2012, 07:03 PM   #10
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GFEP Protection for Heat-Trace roof cables?


Assuming these have normal 15 or 20A plugs, you can't use a 30A breaker on the circuit. You must use 20A, and either reduce the load or use two circuits. Perhaps a 20A multiwire branch circuit would be the way to go, with a 2-pole 20A GFPE breaker.
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Old 05-17-2012, 10:14 PM   #11
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GFEP Protection for Heat-Trace roof cables?


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Old 05-17-2012, 10:30 PM   #12
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GFEP Protection for Heat-Trace roof cables?


These are 120V heaters. You should use a 2 pole 15A breaker and run a 3 wire MWBC to two GFCI outlets under the roof soffit. You don't need to add currents together since each heater cable will be on a different phase in the MWBC. You can decide if you want a GFEP or not. I would try a regular 2 pole breaker and install two gfci plugs in soffit of roof next to where heater runs begin. If you get nuisance tripping replace the gfci plugs with regular duplex and spring for the $150 2 pole 15A GFEP breaker. Since the heaters are on a shingled wood framed roof there isn't a good path to ground so nuisance tripping might be unlikely with GFCIs. You don't need 10 awg wire either, 14-3 should be fine.

Last edited by curiousB; 05-17-2012 at 10:44 PM.
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Old 06-25-2012, 08:13 AM   #13
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GFEP Protection for Heat-Trace roof cables?


Thanks, so would I use this for the 15A 2P to a MWBC?
http://www.amazon.com/Cutler-Hammer-.../dp/B0078FC8OQ

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