Easy Heat mats

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I have a customer who wanted easy heat mats in his driveway to melt snow. He bought the mats from a local distributer, and had them installed in the concrete driveway before i was there to wire. When i got there i had no wiring diagram, so i looked up the model number he had given me, and the mats were the wrong ones. They are SECCO mats, which are designed and listed for INDOOR heating of flooring, NOT for heating driveways because of the power they use...15 watt per sq. ft. Snow melter mats use 50 watts per sq. ft.

So the customer is angry at distributer because he sold him the wrong stuff. The distributer (a national code inspecter and electrician) came and Reccomended some changes in how i wired the circuits.

I have 6 mats, 2 circuits. The mats were rated 15 wats per sq. ft. = 675 watts per mat.
(18" x 30' long. )

My calculations were 3 amps per mat, so i put 3 mats per circuit. total of 9 amps per ckt
At 240 volts

I have a run of 165 feet to the farthest run. so i ran both circuits in 12 ga. AWG THHN. in 2" conduit.

The distributer wants #8 awg thhn... saying i have a voltage drop issue because 3 mats work and 3 do not. My stipulation is that the farthest from the panel work. I have 242 volts that the end of the last circuit. The mats ohm out to be a complete and not broken. so were down to depth...the concrete finisher doesnt rememebr how deep they installed the mats, maximum depth per specs is 2 inches.

Homeowner wants distributer to pay him for the mats, becuase he sold him the wrong stuff. Distributer is saying i have a voltage drop issue and will not do anything until it was installed to his RECCOMENDATIONS, and concrete guy has no clue.

What can or should i do...I dont want this to go to court...i cant afford the costs
 
Well i forgot to mention...

I work for an electrical contractor, but this customer is a friend of my grandparents who i was working for. I dont want that point to be brought out. I made quite a bit of money and it was all cash.
 

480sparky

Senior Member
Location
Iowegia
Well i forgot to mention...

I work for an electrical contractor, but this customer is a friend of my grandparents who i was working for. I dont want that point to be brought out. I made quite a bit of money and it was all cash.

So, you did some work 'on the side'?.............



No permit.......... no license............ no inspection.......... no taxes...........?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Even using the #12 and a length of 165' to the farthest point your voltage drop is only 2.1%. The distributor sounds like he's just trying to make up for his mistake. The way I see it's really not your problem. If your wiring is correct it should work although the output may not be enough to accomplish what the HO wanted. Sounds like they should have hired an electrician before they installed the stuff. Caveat emptor. :rolleyes:

http://www.electrician2.com/calculators/vd_calculatoradv.htm
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
Do nothing unless they offer to pay you to come change it out...

On the other hand if 480 is right and you could get in trouble for no permit etc... than you might want to take in the rump in order to spare some real trouble.
 

benaround

Senior Member
Location
Arizona
Tell the distributer to supply the #8 and you will put it in, if everything works like it is

suppose to work after that, you'll pay for the wire, if not it's on him. If he is so sure that

it needs #8 he won't blink at it.
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
They are SECCO mats, which are designed and listed for INDOOR heating of flooring...15 watt per sq. ft. Snow melter mats use 50 watts per sq. ft.

You have 242 volts while they are connected and your amp meter shows about 9 amps? If so it is definately Not a voltage problem. Sounds like too deep in concrete.

Either that or he's trying to use these dinky mats (designed to keep your toes warn installed under tile or a wood floor) to melt snow on a drive way....

It will never do a proper job no matter what... The HO is thoroughly [out of luck]!
 
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jrannis

Senior Member
If you have the full voltage when the mats are on, then you do not have a voltage drop problem.
This is the only solution I know of:
Have the slab cut and removed, install the proper mats the proper depth, install the correct size wire and it will work.

Do not let anyone intimidate you for working for or helping out your family, especially grandparents. Just think of how they could be taken advantage of. A good example would be the all knowing mat salesman.
Don't get bullied by this character.
If he was an electrician then he should know enough basic theory to understand voltage drop.
I wouldn't do another thing until he admitted that the mats were the wrong type and he at least agreed to a full refund or would deliver the correct mats.
 
Wow i hate ho

Wow i hate ho

I have fought for the homeowner countless hours to get the right mats installed, and finally got the distributer to break in and supply wire, mats, concrete finishing, and all my labor to fix the problem. HO doesnt want driveway ripped up, it'll affect his yard. So he wants me to run the # 8 and see if the other (wrong) mats will work. Then if they dont then he'll consider letting the distributer rip up the driveway...


ARGH>>>!!!

PS we dont see alot of snow, but his driveway is straight up and down and he drives a PT cruiser...my 4x4 makes the driveway fine, but his spins like crazy...i told him to forget about the mats and buy a 4x4
 

surf more

Senior Member
Location
eastern NC
bummer--everyone will learn from all these mistakes(hope so)
#1)do not engage in electrical work away from your own home without ecl
#2)salesman needs to make himself clear,about what he is providing
#3)ho might need to hire a general contractor next time((to organize))



seems like 95% of ho that try to manage a project,are not on top of the situation!!!
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Tell him to back up the driveway. (Front wheel drive - backing up a hill puts the weight on the front wheels.)

Steve
 
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