ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
RV Forums
by BigB - 08/07/22 12:05 PM
NEC- 314.23 (H) (1)
by GWEnergy - 08/07/22 10:40 AM
Wiring method choice
by gfretwell - 08/07/22 01:29 AM
Back From Retirement
by Bill Addiss - 08/05/22 07:39 PM
Load Calcs for EVs and RVs
by renosteinke - 08/04/22 07:34 PM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 31 guests, and 12 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#221709 02/27/22 07:16 PM
Joined: Apr 2008
Posts: 21
N
Member
Anybody have any experience with Heat Trac stair mats? These have me going crazy! Installed 6 tread heaters and 1 mat last winter. They worked great last winter as far as I know. (No complaints that they were not working, but maybe nobody noticed.) This year, nothing but problems! They supply a power cord with an inline GFI module. Constantly tripping, or the GFCI outlet would trip. I had so much trouble, the owner bought all new tread heaters and a new power cord. Still tripping. I played with them again today and found if I only plugged in three, I could get them to stay on.
So I did some testing since I have six to play with. I found that each mat had a 150,000 ohm resistance between hot and ground, and neutral and ground. Doesn't sound like much, but each mat is leaking .8mA to ground. Multiply that by six and you get 4.8mA of current leakage to ground. I believe GFCI receptacles trip between 3 to 5 mA.. I would also bet the resistance gets lower as the mats get saturated, but have to test that theory!
Interestingly. the installation instructions to not call for a GFCI protected circuit, but, being an outside receptacle, it has to be.
Has anybody experienced similar problems and what did you do to cure the issue?
Thanks.
Dave

Joined: Jul 2002
Posts: 8,419
Likes: 3
Member
NHsparky,
Are you required to use such a low earth leakage device on something like this.
What I'm saying is, could you get away with something like a 30mA device in the panel and still ensure personal protection?
Also, is the use of an actual GFCI tester mandated where you are, are you sure that the GFCI isn't merely nuisance tripping.
We do use heat trace cables over here on frosty ground outside buildings and from last memory they were a Tycab thing and had something like a 20-50 Watt/per metre dissipation, but to put a megohm-meter on them, they used to give a reading of about 40-80 GigaOhms to Earth @ 500V.
Which if you use Ohms Law, works out to very little leakage current.


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
waymag
waymag
dallas, texas, USA
Posts: 70
Joined: January 2002
Top Posters(30 Days)
BigB 3
Popular Topics(Views)
294,640 Are you busy
226,406 Re: Forum
211,643 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5