WarmlyYours Snow Melting & Slab Heating - Manual (Page 8)

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5.4 INSTALLATION UNDER CONCRETE
1. Ensure that the concrete contractor has installed a solid base of 4” to 8” (102 mm
to 203mm) of crushed rock aggregate base and that it is tamped down and ready
for the concrete pour.
2 . It is extremely important that the concrete installer does NOT use any heavy
equipment, machinery, or vehicles over the exposed Heating Cable. During
concrete pours, it is recommended that care be taken to avoid stepping on the
transition portion of cable, where the hot section (green) meets the cold section
(black). This is the location of the factory splice. During this process of installing
the heating product and pouring concrete, it is the responsibility of the electrician
to use a 500 VDC megohmmeter and a multi-meter to keep checking on the
Heating Cables that are currently being worked on top of, to ensure they have not
been damaged, and will be ready for action once the concrete slab has cured.
3. For installations in stairs and ramps that will include hand rails, it is strongly
recommended that the concrete installer pre-sleeve for the posts to avoid any
and all drilling of the concrete. The Heating Cable must be routed around these
sleeves or posts to avoid any direct contact with them. Heating Cables or Mats
must not be allowed to pass thru expansion joint locations. It is recommended
that lines are spray painted on the finished concrete surface by the electrician to
mark off exactly where expansion joints may be located. It is the responsibility of
the electrician and the concrete installer to coordinate their efforts so they avoid
saw-cutting or drilling thru Heating Cables that are no longer visible beneath the
concrete. Following the proposed installation plan from WarmlyYours will help to
ensure this process goes smoothly.
4a. For Two-Pour Installations: The concrete installer pours the first 2” to 3” (51mm
to 76mm) of concrete. While this first pour is still wet, rebar or wire-mesh should
be placed on top of the first pour. The Snow Melting Mats / Cables should be
attached to the rebar / mesh with plastic zip ties, using 3” to 4” (76mm to 102mm)
spacing for free-form type cable. At this time, the electrician must route the cold
lead(s) thru rigid metal conduit(s) to get back to an accessible weatherproof
junction box(es). Care must be taken by the electrician so that none of the
heated section enters any conduit. If a slab-mounted snow sensor will be used,
this is the best time for placement. It should be located in an open area away
from trees or bushes so that snow will easily fall directly on it. Separate conduit
should be used to protect the low voltage sensor wire and must NOT be shared
with any high voltage cold lead from the Heating Cables / Mats. Once conduits
& sensor(s) are placed, the topping pour of concrete can be finished. Again, the
concrete installer(s) must take care not to walk on the hot-cold splice point, and
to avoid damaging the Heating Cables with shovels and rakes. Taping up the
shovel blades helps make them less sharp. Like with asphalt, it’s recommended
that Mats be placed so the mesh faces up, keeping the wire-side-down to help
protect it from the shovels.
4b. For Single-Pour Installations: The wire mesh or rebar is first placed by the
concrete installer or electrician. The electrician then must attach the Heating
Cable to the rebar / mesh with plastic zip ties using 3” to 4” (51mm to 76mm)
spacing for free-form type cable. Then the rebar / mesh must be propped
up with concrete rubble, wire chairs, or brick pavers to the appropriate depth
so that Heating Cable / Mat ends up 2” to 3” (51mm to 76mm) from finished
surface and no deeper. Once rebar / mesh / Heating Cable is all propped up, the
electrician must route the cold leads(s) thru rigid metal conduit(s) to get back to
an accessible weatherproof junction box (es). Care must be taken so that none
of heated section enters any conduit. If a slab-mounted snow sensor will be
used, this is the best time for placement. It should be located in an open area,
away from trees or bushes, so that snow will easily fall directly on it. Separate
conduit should be used to protect the low voltage sensor wire and must NOT be
shared with any high voltage cold lead from the Heating Cables / Mats. Once
conduits & sensor(s) are placed, the pour of the concrete can be finished in one
step. The concrete installer(s) must take care not to walk on the hot-cold splice
and to avoid damaging the Heating Cables with shovels and rakes. Mats should
be placed mesh facing up, keeping the wire-side-down, to help protect it from
the shovels and rakes.
5. The electrician needs to complete final testing of all the Heating Cables / Mats
with a multi-meter and a megohmmeter to verify and record that each Heating
Cable has survived the pour of concrete and is ready for action once the concrete
is cured. These values must be recorded on the warranty card on page 22.