Hospital wiring code question

[sangkim0707]

hey all,

i have been working on hospital jobs for years and something new came up by inspector today

i understand general rules of using hospital grade material wires, outlet etc

but i never used hospital grade for the X-ray machine that is 100A

the reason was i always used shunt trip breaker and Emergency shut off switch for the machine and i never knew if i had to use hospital grade wire for 100A feed..

can you guys give idea how to dispute this objection?

this inspector is first one to point out this to me ,,,

Thank you have a nice day!

 

[mwm1752]

unless your x ray machine plugs into a receptacle in a location requiring hospital grade recepts i can't figure -- ask for a code section -- I did notice that when the code refers to receptacles it does not designate an amperage rating in the normal locations

 

[texie]

What is "hospital grade wire"?

 

[hbiss]

HCF MC cable. Thing is I have never seen HCF larger than #10 so how would you even do 100A? As far as I know it's only required for exam/procedure room receptacle circuits. That would include the x-ray room receptacles. Maybe that's what he talking about?

Yeah, ask for a Code section.

-Hal

 

[mbrooke]

I'm thinking EMT.

 

[texie]

HCF MC cable. Thing is I have never seen HCF larger than #10 so how would you even do 100A? As far as I know it's only required for exam/procedure room receptacle circuits. That would include the x-ray room receptacles. Maybe that's what he talking about?

Yeah, ask for a Code section.

-Hal

I didn't occur to me that the OP was possibly referring to HCF. I assumed he was talking about single conductors as in pipe and wire.

 

[roger]

No fear, feeders (we are talking about branch circuits) do not have to comply with 517.13, which is talking about branch circuits. Another part of this is that an xray is on the secondary of a transformer of some sort.

Roger

 

[hbiss]

But is it a feeder? Seems to me the OP is describing a branch circuit from the panel (shunt trip breaker) directly to the machine. It's irrelevant what's in the machine. But none of that matters anyway.

517.13 Grounding of Receptacles and Fixed Electrical Equipment in Patient Care Areas

Wiring in patient care areas shall comply with 517.13(A) and (B).

(A) Wiring Methods. All branch circuits serving patient care areas shall be provided with an effective ground-fault current path by installation in a metal raceway system, or a cable having a metallic armor or sheath assembly. The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding conductor in accordance with 250.118.

(B) Goes on to specify a redundant ground (HCF cable) for receptacles only.

So it would seem that regular MC or EMT is allowable for this application.

-Hal

 

[hbiss]

Another question comes to mind- does a shunt trip breaker and EMO switch qualify as the required disconnect? Can it be LOTO as required? I think you are OK but...

517.72 Disconnecting Means

(A) Capacity. A disconnecting means of adequate capacity for at least 50 percent of the input required for the momentary rating or 100 percent of the input required for the long-time rating of the X-ray equipment, whichever is greater, shall be provided in the supply circuit.

(B) Location. The disconnecting means shall be operable from a location readily accessible from the X-ray control.

-Hal

 

[roger]

Another question comes to mind- does a shunt trip breaker and EMO switch qualify as the required disconnect? Can it be LOTO as required? I think you are OK but...

517.72 Disconnecting Means

(A) Capacity. A disconnecting means of adequate capacity for at least 50 percent of the input required for the momentary rating or 100 percent of the input required for the long-time rating of the X-ray equipment, whichever is greater, shall be provided in the supply circuit.

(B) Location. The disconnecting means shall be operable from a location readily accessible from the X-ray control.

-Hal

In most xray rooms you will have a local breaker (the disconnect in question) ahead of the transformer which makes the topic of this thread a feeder, the EPO is normally located in the control booth in case there is a need to immediately kill power but it is not the the disconnecting means. If the disconnect is located in the control booth there is no need for an EPO.

In some rooms there may be a door switch that will kill the machine if it is opened during a procedure.

Roger

 

[hbiss]

In most xray rooms you will have a local breaker (the disconnect in question) ahead of the transformer which makes the topic of this thread a feeder, the EPO is normally located in the control booth in case there is a need to immediately kill power but it is not the the disconnecting means. If the disconnect is located in the control booth there is no need for an EPO.

In some rooms there may be a door switch that will kill the machine if it is opened during a procedure.

Roger

I will agree that if there is a breaker located with the machine as a disconnect you would have a feeder supplying it. But that's not the case here and most times a disconnect switch is used, not a breaker.

Again, I disagree with your seemingly saying that there is a separate transformer. In the old days there was a big oil filled box that did contain a transformer- along with full wave rectification (usually mercury-vapor rectifier tubes) and other transformers and control components to supply the "head" with 125kV along with voltage for the motor that spins the anode and the variable filament voltage. So that box is really the "machine", not something separate from the machine.

Today, most modern x-ray machines use inverters that produce high frequency AC that in turn is rectified. Yes, there would be at least one transformer but that can't be considered not part of the machine.

-Hal

 

[roger]

Again, I disagree with your seemingly saying that there is a separate transformer. In the old days there was a big oil filled box that did contain a transformer- along with full wave rectification (usually mercury-vapor rectifier tubes) and other transformers and control components to supply the "head" with 125kV along with voltage for the motor that spins the anode and the variable filament voltage. So that box is really the "machine", not something separate from the machine.

Today, most modern x-ray machines use inverters that produce high frequency AC that in turn is rectified. Yes, there would be at least one transformer but that can't be considered not part of the machine.

-Hal

I am using the term transformer to describe a PDU regardless of what it actually is. After we feed the disconnect all the equipment downstream is part of a machine and is not field wiring anyways. The manufacturer would install the PDU, other equipment, and cabling. The machine cabling and wiring is not branch circuit or feeders under the NEC.

When I commissioned the field wiring for these type rooms I would test for the >.01 ohm equipotential at the receptacles, gantry, table, chest board, etc... as required by NFPA 99 because it was "fixed equipment" in the room.

Roger