Cable trays in hospitals.
- Thread starter rbb
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: Cable trays in hospitals.
I?ll plead ignorance for the moment. I don?t see enough information in the original question to discern whether there is a violation of either of the two cited articles. 392.3(A) does allow single conductors in a cable tray system, sometimes. 517.30(C)(3) forbids normal and emergency conductors to share a cable tray. But the original question does not make clear that the cable tray under consideration includes both normal and emergency conductors.
What am I missing?
I?ll plead ignorance for the moment. I don?t see enough information in the original question to discern whether there is a violation of either of the two cited articles. 392.3(A) does allow single conductors in a cable tray system, sometimes. 517.30(C)(3) forbids normal and emergency conductors to share a cable tray. But the original question does not make clear that the cable tray under consideration includes both normal and emergency conductors.
What am I missing?
Re: Cable trays in hospitals.
are they single conductors or cable???
392.3 Uses Permitted.
Cable tray shall be permitted to be used as a support system for services, feeders, branch circuits, communications circuits, control circuits, and signaling circuits. Cable tray installations shall not be limited to industrial establishments.
are they single conductors or cable???
392.3 Uses Permitted.
Cable tray shall be permitted to be used as a support system for services, feeders, branch circuits, communications circuits, control circuits, and signaling circuits. Cable tray installations shall not be limited to industrial establishments.
Re: Cable trays in hospitals.
Charlie:
In the 2002 code, 517.30(C)(3) is mechanical protection of the emergency system.
But at any rate, single conductors cannot be installed in a cable tray in a hospital.
Steve
Charlie:
In the 2002 code, 517.30(C)(3) is mechanical protection of the emergency system.
At first I wondered if a solid (non-ventillated) cable tray would satisfy this. Not I am wondering if a ventilated cable tray would also satisfy this. The paragraph doesn't say anything about "totally enclosed".
But at any rate, single conductors cannot be installed in a cable tray in a hospital.
Steve
Re: Cable trays in hospitals.
I agree that 392.3 (B) limits the use of single conductors in Cable Tray to Industrial Locations.
Cable Tray it self may be used any where as I read it.
Is a MI Single Conductor Cable a Single Conductor?? I am having that discussion as we speak else-where.
I'd be interested to see some more responses
Charlie
I agree that 392.3 (B) limits the use of single conductors in Cable Tray to Industrial Locations.
Cable Tray it self may be used any where as I read it.
Is a MI Single Conductor Cable a Single Conductor?? I am having that discussion as we speak else-where.
I'd be interested to see some more responses
Charlie
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Cable trays in hospitals.
In absence of a reference to Art 310, Table 392.3(A) does not permit general use of single conductor cables in Cable Tray unless they are also part of another ?recognized? method in the Table. Section 392.3(B) [via 392.3(B)(1)] only permits single conductors in ?industrial establishment? applications.
Section 517.30(C)(3) only recognizes ?raceways.? In general, cable trays aren?t raceways, at least in the US. Whether ?covered? cable trays are raceways or not we can leave to future debate.
In short, Roger?s short answer was correct.
In absence of a reference to Art 310, Table 392.3(A) does not permit general use of single conductor cables in Cable Tray unless they are also part of another ?recognized? method in the Table. Section 392.3(B) [via 392.3(B)(1)] only permits single conductors in ?industrial establishment? applications.
Section 517.30(C)(3) only recognizes ?raceways.? In general, cable trays aren?t raceways, at least in the US. Whether ?covered? cable trays are raceways or not we can leave to future debate.
In short, Roger?s short answer was correct.
Re: Cable trays in hospitals.
Yes I also agree that 517.30(C)(3) requires EM SYSTEMS in hospitals be mechanically protected.
My concern is towards Type MI Cable. It is recognized under this section as a stand alone wiring method (without the use of a raceway)if one chooses to install it in a Cable Tray (a means of support and Not a wiring method).Table 392.3A recognizes MI in Cable Tray??? I believe it would be ok YES/NO???
Yes I also agree that 517.30(C)(3) requires EM SYSTEMS in hospitals be mechanically protected.
My concern is towards Type MI Cable. It is recognized under this section as a stand alone wiring method (without the use of a raceway)if one chooses to install it in a Cable Tray (a means of support and Not a wiring method).Table 392.3A recognizes MI in Cable Tray??? I believe it would be ok YES/NO???
rick hart
Senior Member
- Location
- Dallas Texas
Re: Cable trays in hospitals.
This is part of the emergency standby system that is normally de-energized, right? We are talking about the run from generator to a switchboard that feeds transfer switches the emergency power? If so, there will not be a way to mix the different systems required to be kept separate because they have not been established at this point. 517.230 C
I don't think that cable trays can be defined as a raceway either. In section 100 a raceway is defined as enclosed. Cable trays allow flexibility and that is not something desired in an emergency supply.
Having said that, an engineer that puts his stamp on a design can do something like this if there are circumstances that would prohibit conduit or wireway. He assumes the liability for installation "under engineering supervision".
This is part of the emergency standby system that is normally de-energized, right? We are talking about the run from generator to a switchboard that feeds transfer switches the emergency power? If so, there will not be a way to mix the different systems required to be kept separate because they have not been established at this point. 517.230 C
I don't think that cable trays can be defined as a raceway either. In section 100 a raceway is defined as enclosed. Cable trays allow flexibility and that is not something desired in an emergency supply.
Having said that, an engineer that puts his stamp on a design can do something like this if there are circumstances that would prohibit conduit or wireway. He assumes the liability for installation "under engineering supervision".
Re: Cable trays in hospitals.
I see that now Roger
And the definition lists just about everything except cable trays.
cpal:
I also think type MI cable in a duct would be OK. But I think the pharse "single conductors" refers to wires normally installed in a raceway, like THHN/THWN.
Steve
I see that now Roger
And the definition lists just about everything except cable trays.
cpal:
I also think type MI cable in a duct would be OK. But I think the pharse "single conductors" refers to wires normally installed in a raceway, like THHN/THWN.
Steve
Re: Cable trays in hospitals.
517.30 does not prohibit MI Cable .392.3 (A) does not prohibit MI Cable.
392.3(B) implies that single conductors may only be installed in Cable Tray when the conductors and tray are installed in industrial locations.
I just want to clarify that my question regards installing type MI in a hospital with that wiring method supported by Cable Tray.
But I am getting a clearer picture of the entire discussion thanks everyone!!
Charlie
517.30 does not prohibit MI Cable .392.3 (A) does not prohibit MI Cable.
392.3(B) implies that single conductors may only be installed in Cable Tray when the conductors and tray are installed in industrial locations.
I just want to clarify that my question regards installing type MI in a hospital with that wiring method supported by Cable Tray.
But I am getting a clearer picture of the entire discussion thanks everyone!!
Charlie
rick hart
Senior Member
- Location
- Dallas Texas
Re: Cable trays in hospitals.
MI cable in a tray is not a problem; I'm really not sure MI would be a problem without any raceway, wireway, what have you.
I thought we were talking 75C building wire conductors when speaking of single conductors. With the MI you have a practically bullet proof installation. I have seen that stuff run directly to a fire pump transfer switch from a pad mounted 600KVA transformer output- just bundled together, hanging from one hole straps under a hospital. Engineering drawing stamped by P.E. and everything.
I'm anxious to see what that comment stirs up. It's true.
MI cable in a tray is not a problem; I'm really not sure MI would be a problem without any raceway, wireway, what have you.
I thought we were talking 75C building wire conductors when speaking of single conductors. With the MI you have a practically bullet proof installation. I have seen that stuff run directly to a fire pump transfer switch from a pad mounted 600KVA transformer output- just bundled together, hanging from one hole straps under a hospital. Engineering drawing stamped by P.E. and everything.
I'm anxious to see what that comment stirs up. It's true.
Re: Cable trays in hospitals.
I agree, if we are using MI cable, raceways or trays would only be an added luxury and not necessary, in otherwords a moot point.
Rbb, IMO the Emergency System starts at the Alternate Source, pretty much as shown within the brackets of the "emergency system" in FPN Figures 517.30 No.1 and No.2.
Roger
I agree, if we are using MI cable, raceways or trays would only be an added luxury and not necessary, in otherwords a moot point.
Rbb, IMO the Emergency System starts at the Alternate Source, pretty much as shown within the brackets of the "emergency system" in FPN Figures 517.30 No.1 and No.2.
Roger
Re: Cable trays in hospitals.
Rick:
That fire pump sounds like a good application of MI cable. You can get MI cable with a 2 hour fire rating. See 695.6(B) of the 2002 NEC.
Also see:
MI cable info
Steve
Rick:
That fire pump sounds like a good application of MI cable. You can get MI cable with a 2 hour fire rating. See 695.6(B) of the 2002 NEC.
Also see:
MI cable info
Steve
Re: Cable trays in hospitals.
Roger:
I'll be the first to admit I'm not sure about this, but I am starting to think the emergency system starts at the transfer switch. Notice that the diagrams only show vertical brackets around the generator for the "essential electrical system". The "emergency system" only has a horizontal bracket on the load side of the transfer switch.
I'm also thinking that everything on the line side of the xfer switch is backed up (there is normal and emergency power).
I'm not saying I disagree, but I wish there was something that made it a little clearer.
Steve
Roger:
I'll be the first to admit I'm not sure about this, but I am starting to think the emergency system starts at the transfer switch. Notice that the diagrams only show vertical brackets around the generator for the "essential electrical system". The "emergency system" only has a horizontal bracket on the load side of the transfer switch.
I'm also thinking that everything on the line side of the xfer switch is backed up (there is normal and emergency power).
I'm not saying I disagree, but I wish there was something that made it a little clearer.
Steve
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