Radiation treatment facility

[jafsparky]

We are building a radiation/oncology clinic. Conduits for the radiation equipment will run under the concrete slab to a pit directly below the equipment. Power conductors will run free air from the pit up into the equipment. Does the radiation treatment room fall under the definition of "patient care area"? Do the conduits under the slab need to be compliant to 517.13? And if so, 358.10(b) allows EMT to be ran under the slab. Has anyone had experience with this? Does EMT hold up in the earth?

 

[al hildenbrand]

The 2005 NEC Handbook, in 358.10 has this explanatory note:

According to the 2004 UL General Information for Electrical Equipment Directory (White Book), category FJMX, galvanized steel electrical metallic tubing (EMT) installed in concrete, on grade or above, generally requires no supplementary corrosion protection. Galvanized steel EMT in concrete slab below grade level may require supplementary corrosion protection. In general, galvanized steel EMT in contact with soil requires supplementary corrosion protection. Where galvanized steel EMT without supplementary corrosion protection extends directly from concrete encasement to soil burial, severe corrosive effects are likely to occur on the metal in contact with the soil.

 

[Bill W]

I've had several recent jobs at radiation treatment centers. Yes this is a patient care area. In one case I was involved with, the feeders terminated onto a shunt-trip before supplying the equipment, so pvc was suitable. In another case, that sounds similar to yours, emt was slabbed. The emt should be supported so as to be encased in the slab, not sandwiched between it and the Earth. The code reads, "shall be permitted to be installed in concrete,...in direct contact with the earth,...or in areas subject to severe corrosive influences...

 

[infinity]

I'm with Bill. The EMT should be within the concrete not below it.