DITRA-Heat Testing & Why an alert device is not sufficient.

Schluter requires 3 tests for a 10 year warranty, and a 4th test for an additional 5 years.  We push 3 sets of tests at 3 different times during a wire installation.  We do this because a resistance alert device will only tell you one thing - has a wire been completely cut.  There is further damage that can happen to a wire that will affect its performance and life without an alert device ever ‘screaming’ at you.

ANATOMY OF A WIRE

Every wire will have two conductors on the cold lead end, which plug into the LOAD side of the thermostat.  Every wire will have a black conductor, regardless of 120 or 240 volt.  A 120 volt wire will have a black with a white or yellow, and every 240 volt wire will have a black with a red.  Visually I can tell what voltage the wire is just by the color of the insulation around the conductors.  

Ground braid is wrapped around the two conductors from one end of the wire to the other.

Cold Lead is referring to the black part of the cable. This is the part of the wire that runs up the conduit in the wall to the thermostat.  This is the only section of wire that CAN be cut - or it can be extended.  If the cold lead is cut short, PLEASE MAKE SURE TO REATTACH THE SILVER TAG with one of the replacements we provided in the heat cable box.  This contains important information we need to diagnose the floor if there ever was an issue.  It will void a warranty if removed.  More on the silver tag below.

Cold Splice is referring to the knuckle junction - or splice - where the cold leads meets the heating conductors, or the gray part of the cable.  This MUST be embedded under the tile in thinset mortar as it does heat up from this point to the end of the wire.

End Splice is simply the end of the cable.  This does not return to the thermostat, but terminates in the field.

SILVER TAG

Hopefully we never have to see you at a job site to diagnose a floor that is not heating.  If we do come to the job, we will need this information.  Without it we are legally and technical bound from assisting with any repairs on the wire.

Critical information includes serial number, voltage, SF size of wire, amp draw and resistance rating for that wire.

TEST 1 | RESISTANCE TEST

Is the wire broken?  Is the wire cut?  This is what the resistance alert device will tell you, but only if the wire is completely cut.

The resistance reading should be within 10% of the resistance reading on the silver tag.  You can see the resistance number of the tag in this picture and the reading that I have on the device.  This tells me there is NO break in the wire.  I have resistance that matches the factory measurement.  

HOW TO DO THIS TEST: Look for the ohms symbol on your device. This is the ‘upside-down horseshoe’ symbol.  Ω Connect one clamp/probe to each heat wire lead - there is no polarity - color does not matter. We are simply verifying that there is resistance between the two leads. You should get a reading writhing 10% of the resistance printed on the silver tag. This means there is no break in the wire.

TEST 2 | CONTINUITY TEST

Is the ground braid touching the conductors at any point from one end of the wire to the other?  

With this test we DO NOT WANT RESISTANCE.  Resistance would mean contact; we don’t want contact with the ground braid.  We are looking for readings of OL (open loop), or some devices will read 22 or 1. Test each lead to the ground and record each result.

HOW TO DO THIS TEST: This is the same setting as test one.  Ω Connect one clamp/probe to a heat wire lead, and the other clamp/probe to the ground braid - color does not matter. We are verifying that there is no resistance between the ground braid and each lead. You should get an OL reading. This means there is contact with each lead to the ground braid.

TEST 3 | INSULATION TEST (OPTIONAL)

This will test the integrity of the insulation around the conductors to see if there is cracks that could lead to a fault with the ground braid that is wrapped around them.  This test is optional, but we do recommend it.  This will give you an additional 5 years on the 10 year warranty.  It will require use of a Megger/Megohmmeter (with my luck I’m spelling that wrong).  We do sell those at cost to contractors; we offer the AEMC model.  This device can do all three tests.

As with test 2, we want a reading of OL.  This means there is no bleeding to the ground braid through the insulation.  Some devices may read 2200. Test each lead to the ground and record results.

HOW TO DO THIS TEST: You will need a megohmmeter. You can buy those direct from Schluter or through 3rd party sources (Amazon). They range from $150 to $400. This test is not required, but strongly recommended. It will give an additional 5 years to the warranty. If there is a nick in the insulation that could lead to a ground fault, this device will detect it. Megger setting will be 1000V - you will connect one probe/clip to the lead and the other to the ground for this test. You are looking for an OL or 2200 reading (depending on device).

These three tests should be done at three intervals:

1 | While the wire is still on the spool.

2 | After the wire as been snapped into the membrane.

3 | After the tile has been set, but before you grout.