Tests & Results

Watch The Width

Recent testing by BD Loops shows the width of the saw-cut critical to preventing defects in the installation of inductance loops. The following chart data shows the importance of using the proper saw-cut width to provide space for epoxy/sealant to completely flow around the loop wires to minimize air spaces between the wires. Air spaces between wires can fill with water, which can freeze and cause the wires to become exposed by pushing them out of the saw-cut groove. Air spaces allow movement of the wires within the groove, this movement can be caused by any form of ground vibrations resulting in a false detection.

Test data shows that even when using the thinnest two-component polyester epoxy sealant on a 1/8” groove, there was not enough space between the wires and the saw-cut wall to allow the epoxy to fill the void. A Polyurethane sealant was also used and its data is listed below. Bondo P-606V epoxy had a viscosity of 4,000 – 7,000 cps (much like the consistency of hot honey). The other, Chemque Q-seal 290S had a viscosity of 9,000 – 30,000 cps (the consistency of thick ketchup).

Clearance Chart:

Saw Blade WidthWidth Of CutWire GageWire SizeClearanceWire Vendor
New 1/8”.12520.118.007**Brand X
Used 1/8”.11118.109.002**Brand Y
New 3/16”.18716*Built in backer rod*BD Loops
Used 3/16”.18316*Built in backer rod*BD Loops

*BD Loops are designed to fit within a 3/16” groove and has an outer jacket with built in backer-rod that completely seals the bottom portion of the groove, so sealant does not need to flow around the wire.
**  Two sheets of 20# copy paper measures .006 in thickness

Epoxy/SealantWidth Of CutWire GageWire VendorAir Pockets Present
Bondo P-606V.12520Brand XYES
Bondo P-606V.12218Brand YYES
Bondo P-606V.11118Brand YYES
Bondo P-606V.18516BD LoopsNO
Bondo P-606V.18016BD LoopsNO
Chemque Q-seal 290S.12520Brand XYES
Chemque Q-seal 290S.12218Brand YYES
Chemque Q-seal 290S.11118Brand YYES
Chemque Q-seal 290S.18516BD LoopsNO
Chemque Q-seal 290S.17816BD LoopsNO

These tests are supported by the following pictures,
which show clear evidence of the air gaps between the wires.


The 1/8″ Groove test (which can be viewed here) proves that a 1/8” saw-cut (as claimed by some vendors) will not provide durability and reliability due to the high possibility of air pockets forming in and around the loops. The tests clearly indicate the wider 3/16” saw-cut and the preformed loops from BD Loops provide the best possible installation to minimize air pockets and potential failures.

BD Loops

The Loop Experts!

BD Loops was founded in 2001. Their preformed loops and accessories are designed with the installer in mind. BD Loops offers a complete loop system solution including preformed direct burial loops, preformed saw-cut loops, loop sealant, blades, testing devices, and installation tools. BD Loops has a reputation for reliability and ease of installation. They pride themselves on the quality of their products and their commitment to providing excellent customer service and support. BD Loops preformed loops are made in the USA at their facility in Placentia, CA.