Wiring Options: Patient Care Areas
Patient care areas of health care facilities are surrounded by metal equipment, liquids and various electronic equipment. This type of environment yields big potential for stray currents that can be detrimental to patients. Because of these issues, both normal and emergency branch circuit wiring in these areas must have redundant forms of grounding.
Section 517.13 of the National Electric Code® (NEC®) requires that any branch circuit wiring that feeds patient care areas must have two things: (1) the metal conduit or metal sheath of a cable must qualify as a grounding conductor, and (2) a green insulated grounding conductor must be installed and connected.
There are additional requirements for emergency power. NEC Section 517.30(C)(3) requires the emergency system wiring to be mechanically protected. Additionally, if the wiring is installed in patient care areas it must comply with 517.13(A) and (B).
In the past, designers and installers of health care facilities had only two choices when selecting their branch circuit wiring: pipe and wire or Health Care Facility (HCF) Type AC cable.
1. Pipe and Wire
This wiring method requires more planning, has more components, and requires more time to install than Type HCF AC cable. The pipe or conduit is available in a variety of diameters and comes in 10-foot lengths with Electrical Metallic Tubing (EMT) being the most common product used. The pipe is rigid and must be bent in the field as needed to achieve the desired routing. Couplings are required to join the10-foot sections. Once the conduit is installed, the electrician must come back and manually pull the wire through. It’s a lengthy and tedious process. Per section 517.13 of the NEC, the metal conduit qualifies as a grounding conductor and the addition of a green ground provides the redundant ground requirement. While the conduit ground path can be very good, the connection or ground path integrity is only as reliable as the couplings that connect the conduit.
2. HCF AC Cable
Type HCF AC cable is commonly selected for its advantages over pipe and wire branch circuits. HCF AC cable has wires preinstalled, which means there is no need to pull the wire. It is flexible and continuous which eliminates the need for field bending and couplings. With HCF AC cable, the multistage installation process of pipe and wire is gone, resulting in both speed and cost advantages. Per Section 517.13 of the NEC, the armor qualifies as a grounding conductor and the addition of a green ground provides the redundant ground. The armor ground path is reliable because it does not have couplings that can loosen over time, however the ground path performance is not as good as a copper grounding conductor.
Now there is a better choice, a new form of healthcare cable that is a MC cable product for healthcare facilities, HCF MCAP® cable. HCF MCAP cable, offers improvements in grounding performance and reliability, installation productivity, and installed cost over both pipe and wire and Type HCF AC cable.
3. HCF MCAP Cable
All HCF cables are not equal. HCF MCAP cable replaces Type AC cable and with it brings a significantly better armor ground path performance – over 350 percent on 12 AWG cable - and vastly improved installation performance. What does that mean for you? Improved grounding performance and reliability.
12 AWG HCF Cable
Additionally, HCF MCAP cable is a Type MC cable, not a Type AC cable, making it easier to install and allowing for more conductors in the cable. Unlike HCF Type AC cable, which is limited to four current carrying conductors, there are no limits on the number of conductors allowed in a cable. That means you can use multiple neutrals and home run cables where HCF MCAP cable is used. All this adds up to better grounding, increased installation productivity, and faster completion.
|HCF MCAP cable with multi-neutral and multi-conductor for home|
Emergency Wiring in Health Care Facilities
There are different wiring methods permitted per NEC Section 517.30(C)(3). The most common item method is item (1) however item (3) is permitted as prescribed below:
(1) Nonflexible metal raceways (such as EMT, IMC and RMC), Type MI cable, or schedule 80 PVC conduit. Nonmetallic raceways shall not be used for branch circuits that supply patient care areas.
NOTE: There is no restriction on the use of nonflexible metal raceways. Nonmetallic nonflexible raceways are not permitted in patient care areas.
(3) Listed flexible metal raceways and listed metal sheathed cable assemblies (such as HCF Type AC cable and HCF MCAP cable which do comply with 517.13(A) and (B) for patient care areas) in any one of the following:
a. Where used in listed prefabricated medical headwalls
b. In listed office furnishings
c. Where fished into existing walls or ceilings, not otherwise accessible and not subject to physical damage
d. Where necessary for flexible connection to equipment
Note: If any of these conditions are not present, then default to item (1).