# Thhw xhhw?



## BBQ (Nov 16, 2010)

m sleem said:


> My question is ((material of the elctrical wires in healthcare facilities better to be 600v THHW or 600/1000v XHHW)) WHAT CODE SAYS?


In general THHN/THWN is fine. 

However for operating room isolated power supplies you will often need XHHW for it. To meet the manufactures specifications and so the current leakage is kept to a minimum.


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## m sleem (May 16, 2012)

BBQ said:


> In general THHN/THWN is fine.
> 
> However for operating room isolated power supplies you will often need XHHW for it. To meet the manufactures specifications and so the current leakage is kept to a minimum.


Actually befor i have designed complete hospital and specified XHHW(PVC/XLPE) for the whole project (offices + medical care units). so my question is (is there recommendation in code for the wire's material? )


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## BBQ (Nov 16, 2010)

m sleem said:


> Actually befor i have designed complete hospital and specified XHHW(PVC/XLPE) for the whole project (offices + medical care units). so my question is (is there recommendation in code for the wire's material? )


There is no NEC rule requiring 1000 volt insulation for circuits below 600 volts.


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## brian john (Mar 11, 2007)

BBQ said:


> In general THHN/THWN is fine.
> 
> However for operating room isolated power supplies you will often need XHHW for it. To meet the manufactures specifications and so the current leakage is kept to a minimum.


Bob, I have never heard this before, is the XHHW insulation suppose superior in regards to leakage?


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## BBQ (Nov 16, 2010)

brian john said:


> Bob, I have never heard this before, is the XHHW insulation suppose superior in regards to leakage?


Yes, it has a higher dielectric rating than THHN, the run lengths still have to be short.


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## Roger. (Dec 18, 2011)

brian john said:


> Bob, I have never heard this before, is the XHHW insulation suppose superior in regards to leakage?


Yes, the XHHW has a better dielectric strength than THWN conductors and as Bob stated, Isolated Power Systems require XHHW, and no wet type pulling compounds, you can use powdered soap stone

Roger


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## Roger. (Dec 18, 2011)

Or what Bob just said. 

Roger


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## BBQ (Nov 16, 2010)

Roger. said:


> Or what Bob just said.
> 
> Roger


I was thinking of the white paper you had posted more years ago than I want to admit. 


BTW, I don't think my supplier has powered soap stone, where would I get that?


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## Roger. (Dec 18, 2011)

BBQ said:


> I was thinking of the white paper you had posted more years ago than I want to admit.


The years have sped by haven't they. 

Roger


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## brian john (Mar 11, 2007)

Roger. said:


> Yes, the XHHW has a better dielectric strength than THWN conductors and as Bob stated, Isolated Power Systems require XHHW, and no wet type pulling compounds, you can use powdered soap stone
> 
> Roger


When setting large lead acid batteries on of the approved methods of lubricating the rails is Talcum, is talc approved for pulling conductors.

WOULD BE A MESS, I have only ever been on one job were Talc was used for setting batteries and cleaning the jars was next to impossible. I would have set the jars myself, in lieu of all the cleaning involved.


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## Roger. (Dec 18, 2011)

brian john said:


> is talc approved for pulling conductors.


Personally I don't see why not but, I have never seen it specifically mentioned in any manufacturers literature. (not saying it's not there) Normally the runs are short so no lubricating is necessary.

Roger


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