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Post by Deleted on Feb 10, 2017 8:14:21 GMT -6
426.28 states ground fault protection of equipment shall be provided for fixed outdoor electric deicing and snow melting equipment.
1) Why is there even different levels of GFI protection (personnel protection at 5ma and equipment protection at 30ma) is that a significant difference? (may be podcast idea) I find it hard to find a scenario where a ground fault between 5ma and 30ma would hold there, so why not just make 1 GFI trip level at the 5ma level to take care of all (I'm all about the KISS principle , Keep it simple stupid)
2) With the code being all based on safety why would it allow for GFI equipment protection on heat tape that runs through a gutter and down spout that is outdoors and is generally a conductive material (aluminum I'm thinking about) at a height that folks can contact easily?
3) Based on the principle that the code is a minimum standard I believe using a personnel protection GFI device on a gutter heat tape would be ok as it trips at a lesser level.
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Post by Electrical Code Academy Staff on Feb 10, 2017 9:55:44 GMT -6
Greetings Alpelec,
You have provided some great questions for the GFCI development industry. I can only offer my opinions to the questions in hopes that it sheds some light on my opinion to the situation. Keeping in mind they are only my opinions and others may agree to disagree with both of us my friend.
1) Why is there even different levels of GFI protection (personnel protection at 5ma and equipment protection at 30ma) is that a significant difference? (may be podcast idea) I find it hard to find a scenario where a ground fault between 5ma and 30ma would hold there, so why not just make 1 GFI trip level at the 5ma level to take care of all (I'm all about the KISS principle , Keep it simple stupid)
My Response : The level of potential threshold points with GFCI devices are to follow established mA levels shown to be harmful.. For example, it has been proven that anything less than 4 mA is not harmful while 6 mA and over is potentially harmful. The safe level of a nominal 5 mA was provided by tested from the product manufacturers and supplied data showing the levels of safe human exposure. The use of a 30 mA GFP protection , as referenced in section 426.28 is to protect the equipment itself in many cases and to not necessarily protect human life but to limit the exposure while still protecting the equipment. If the 5 mA is used on heating tape for example, the level of acceptable current leakage would activate the device falsely and due to its location increase a possible hazard. However, you can most certainly use a 5 mA device on this application if the customer desires as the NEC is just saying you don't have to in terms of human protection...only equipment protection.....Now you notice is says "ground-fault protection of equipment" in section 426.28. The nature of the rule has nothing to do with saving a life....it is about the equipment itself so we have two different desires here from the NEC.
2) With the code being all based on safety why would it allow for GFI equipment protection on heat tape that runs through a gutter and down spout that is outdoors and is generally a conductive material (aluminum I'm thinking about) at a height that folks can contact easily?
My Response: Remember this rule in 426.28 is not human protection...only equipment protection. We still have to use common sense in how we install systems to avoid causing a safety issue.
3) Based on the principle that the code is a minimum standard I believe using a personnel protection GFI device on a gutter heat tape would be ok as it trips at a lesser level.
My Response: And I would agree as long as the GFCI provides the protection of the equipment. The protection of human life in this case is a bonus. However, it could result in nuisance tripping based on the acceptable current leakage values established by the "heat tape" folks...which could cause a potential hazard in itself by someone eventually removing the device protecting the heat strip as to then providing no REAL protection at all.
Just some of my thoughts on the subject my friend....GREAT POST !
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Post by Deleted on Feb 11, 2017 7:40:09 GMT -6
Thank you for your response. I hope some others will chime in also. Common sense to me on #2 would be that personnel protection should be used to prevent a down spout from getting energized to a level that can harm a human and where it can be readily encountered. I'd bet you don't have much of a need for this in TX. BTW I have used personnel GFI protection breakers on gutter heat tape many times over the years without nuisance tripping. Then there's the bottom line. EPD's are harder to come by (not in stock as much) and they cost way more and are less protective, a triple wammy.
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