How can you cut a 2sq foot access hole in a posttention slab? I want to add a shower drain.

How can you cut a 2sq foot access hole in a posttention slab? I want to add a shower drain.
You locate the cables by X-ray or a set of builders plans before you make a cut. CAUTION! Those cables are under tension.
Post tension slabs are an everyday reality in our area. X-rays are the best way to locate cables, but if the changes are near the edge of the slab (as they usually are) you can usually go outside and see the small anchor plates where the tension cables end. They have usually been covered over with some type of patch, but you can still locate them. From the plates the cables goe straight through the slab at right angles to the beam. When you've located the cables in the affected area,instead of cutting a trench and destroying cables and their surrounding concrete mass, you punch through a series of small holes from which you can tunnel under for pipes and whatever.
Although the information that has been supplied is valid there are very important issues that are beig overlooked. First and foremost when planning to cut into a PT slab the cables in the cut area need to be detensioned. This a must safety precaution. Next have the cables located In other words , proceed with caution. Radar and x ray are excellent choices. If cables get broken during the jack hammering there are manufacturers of couplers and jacking plates to make needed repairs. When the work is done retension the cables and patch the anchors. I see no mention of a vent. You are planning to vent your shower aren't you? Regards, Tom