How to Cut a Prado Outlet Hole in Quartz and Stone Countertops

A Prado unifit outlet is a small round receptacle that sits in the countertop itself, with a cover plate that can finish level with the stone. For the fabricator the job looks simple on the drawing: one 1-3/8" hole and, for a flush finish, a shallow 1-1/2" recess around it. In a finished quartz or granite top, though, that small opening has to be the right size, in the right place and clean at the edge, because the cover plate will sit on it for the life of the kitchen.

This guide collects the cutout numbers from Prado's own installation documents for the unifit single outlet, explains how countertop thickness and the space under the top affect the job, compares the two ways shops cut the opening, and lays out a test-first routine for the core bit method. It does not cover wiring, which belongs to a licensed electrician.

The Cutout Numbers from Prado

Prado publishes the cutout for the unifit single outlet in its installation overview and in its flush-mount countersink guide. Every mounting style starts from the same installation hole, 1-3/8" (35 mm) in diameter. What changes from one style to the next is the recess cut around that hole.

Prado's flush-mount guide describes the recess as a circular step 1/16" (1.5 mm) wide around the entire hole and 1/10" (2.5 mm) deep, which is what lets the cover plate finish level with the countertop. Prado marks both flush-mount options "wood and stone only". Its documents say "stone" without naming engineered quartz, so confirm with Prado that the surface on the job is covered. Prado also reserves the right to change technical details without notice where the change does not affect appearance or function, so download the current cutout template for the model on the drawing before anyone cuts. The numbers in this guide are for the unifit single outlet; other Prado outlets have their own templates.

Check Thickness and the Space Below the Top

Prado lists a material thickness range for the unifit single: 1/4" (6.4 mm) to 1-3/8" (35 mm) for surface mounting, and 11/32" (8.7 mm) to 1-1/2" (38.1 mm) for flush mounting. Standard 2 cm and 3 cm (20 and 30 mm) tops, about 3/4" and 1-3/16", fall inside both ranges. Where the material is thicker than required, Prado says to machine it down to the correct depth; where it is thinner, it says to add a plate, which its drawing shows as wooden, to make up the depth.

The outlet also needs room below the top. Prado gives an outlet depth of 2" (51 mm) for the hardwired version and 2-2/3" (68 mm) for the self-contained version, and an outlet length of 2-1/4" (57 mm) for the corded version. The hardwired version installs with a back box and back box cover plate, while the self-contained version uses its cap and needs no back box. Check the cabinet drawings for drawers, rails and sink bowls under the location before the slab is cut. Our guide to Pop-Up Power Outlets in Stone Countertops: Cutouts and Planning covers who owns each layout decision and how the electrical code affects island receptacles.

Two Ways to Cut the Opening

CNC, as Prado specifies for stone

For hard materials, which Prado lists as stone, tile, metal and glass, the flush-mount guide calls for the hole to be cut by CNC machine, waterjet or laser, and for the countersink to be cut by CNC machine only. On a CNC the shop cuts the 1-3/8" hole and then mills the recess to Prado's diameter and depth. For porcelain and ultra-compact surfaces on a 5-axis CNC, the APEXX Thin-Wall CNC Core Bit comes in a 1-3/8" diameter with a 1/2"-gas reverse thread.

A countersink core bit

Some shops that drill the hole with a core bit use a countersink core bit with the same two diameters. The APEXX countersink core bit, item 22229-07006, has a 1-3/8" core and a 1-1/2" tapered diamond rim on a 5/8"-11 female thread. The core cuts the installation hole, and the tapered rim cuts a countersink at the surface as the bit goes in.

Two differences from Prado's drawing matter. First, a tapered rim leaves a sloped countersink, not the flat-bottomed step Prado shows, so check how the cover plate seats in it. Second, Prado's guide calls for a CNC to cut countersinks in stone. Treat the core bit route as a shop method you prove on an offcut before cutting the countertop. Also pick the right size: the 1-3/8" x 2" rim bit in the same family (22229-07005) is wider than Prado's 1-1/2" recess, and none of the sizes in this countersink line has a 1-3/4" rim for the trim-ring recess, which stays a CNC job.

A Test-First Routine for the Core Bit Method

1. Confirm the outlet model, the mounting style and the current Prado template against the drawing, and confirm the location with the electrician.
2. Cut a test hole in an offcut of the same material and thickness. Prado recommends testing the process on a sample of the material before the final installation.
3. Seat the cover plate in the test hole. If it does not sit flush and centered, change the method or move the countersink to the CNC before going near the countertop.
4. Mark the center on the finished top from the drawing.
5. Mount the bit on the drill with the correct adapter for its 5/8"-11 thread. Start at low RPM to establish the hole, apply steady, even pressure without forcing the bit, and use water when wet drilling to cool the bit and extend its life.
6. Go in until the countersink at the surface matches the test piece at the full 1-1/2" diameter. Measure the countersink depth too: a tapered rim does not cut the same flat 1/10" (2.5 mm) step as Prado's drawing.
7. Clean and dry the opening and test-fit the cover plate before the top leaves the shop.

Always wear appropriate PPE. For the general technique of stepped holes in stone, see Countersinking and Counterboring Stone for Flush Fasteners, and for core drilling practice see Diamond Core Drilling: Faucet and Fixture Holes in Stone.

Leave the Wiring to the Electrician

Prado states that installation must be carried out by a qualified professional and that it is not liable for incorrect hole drilling. The fabricator's scope ends at a clean, correctly sized opening in the right place. Connections, circuit protection and code compliance belong to a licensed electrician working with the authority having jurisdiction.

Prado and unifit are trademarks of their owner. The bits named here are not made or endorsed by Prado. Dimensions are taken from Prado's published installation documents at the time of writing; always cut to the current template for the model being installed.