I am wiring a refrigerated storage building. It has heat tape incorporated on one of the drain lines. In order to supply a means of disconnect, I am planning on putting a plug on it and installing a receptacle. The problem is that the heat tape only has two wires ( no equipment ground ) Do I put a two wire plug and an ungrounded receptacle, or a 3 wire plug and 3 wire receptacle, even though it has no equipment ground???? Haven't talked to the inspector yet, and thought I would get some opinions, just in case I didn't catch him before he left his office in the morning.. Also does anyone know a code reference for the installation procedures inside a freezer. Is it considered a wet location?? Looks like it would only be if the compressors failed. I am mounting weatherproof boxes, but what kind of cover do you think you would put on this receptacle I am putting for the heat tape?? An in use cover maybe?? Thanks for the input... Steve
SparkyNC My 2 cents: I would use a 2 wire twistlock plug and receptacle, and a "in-use cover.
My reasoning for the 2 wire twistlock is that it's not a "common" receptacle that someone could use if they removed the plug.
Did you think about "hard wiring" the heat tape, and using a snap switch?? We have PVC FS Boxes with a switch handle cover, that's lockable. A 30 amp, 2 pole spec switch fits without a problem.
As to the wiring methods, the only thing re: freezers in my memory bank is to seal the conduits going from the freezer to the adjacent area to prevent condensation, due to the temperature differentials. I don't mean Exp Proof seals, just duct seal.
sparkync, Most of my work these days is wiring these cold-rooms, so if you need any further advice after I have submitted this, just ask away!, A drain heater, as a rule, should not require an isolator on it, provided that it is supplied from the same circuit as the refrigeration circuit that it protects, remember, this heater, is only rated at 20-40Watts and it must be continuously energised, as if it fails, the drain will block. Everything associated in a Cool-room or freezer, must be waterproof, using Silicone sealant, where it is required, will help, but using IP Rated (NEMA) fittings from the start, is a mandatory thing,with these types of environments, especially where condensation is concerned.
On several cold storage warehouses, we install an single 20 amp outlet near the drain line on the freezer side of the wall seperating the dock and freezer spaces. We terminated the self regulating heat tape with an 20 amp grounded plug. Sealed the conduit passing thru the wall after the wire was pulled in with duct seal. This installation was accepted in nine different jurisdictions. You will need to do this with each seperate heat tape run. Make sure the length of heat tape will not over load the c/b rating (16 amps for a 20Amp circuit). The number of circuits will depend on how much drain line needs to be heated vs. the length recomended by the manufacturer. We found it very helpful to mark the end of line(EOL) for each run. Most of the troubles were with EOL or cord cap terminations becoming loose due to vibration and /or corrosion. Use the tape recomended for the heat tape by the manufacturer. We had problems with other types of tape and tie wraps falling apart or melting. Hope this helps you out.
427.23 Grounded Conductive Covering. Electric heating equipment shall be listed and have a grounded conductive covering in accordance with 427.23(A) or (B). The conductive covering shall provide an effective ground path for equipment protection. (A) Heating Wires or Cables. Heating wires or cables shall have a grounded conductive covering that surrounds the heating element and bus wires, if any, and their electrical insulation. (B) Heating Panels. Heating panels shall have a grounded conductive covering over the heating element and its electrical insulation on the side opposite the side attached to the surface to be heated.
How do you have a heat tape without an EGC? Also 427.22 requires GFP for the heat tape. Don
As someone who does alot of refrgeraiton work, I offer the following.
This is a wet location, even when frozen. The evaporator coil will have regular defrost cycles two to 4 times a day with either an electric heating coil coming on for a few minutes or a valve opening allowing hot refrigerant to flow through the coil for a few minutes. And of course the heat tape keeps the drain line and drain pan pretty wet all the time.
Ice often builds up around the evaporator and fan assembly. sometimes an enormous amount of ice, it will grow into your electrical boxes, thermostats, and anywhere you have electrical connections. This usually indicates too long or too frequent defrost cycles but it happens alot. I've been shocked a couple of times reaching behind one of these units just because the big block of ice was in contact with some wire somewhere. I've had t-stats stuck because they were frozen in this block of ice and the freezer ran continuously.
I don't know what code requires but I wish these things were always designed to be water tight even if run at the bottom of a lake.