MI Cable for critical branch wiring

[mshields]

I am in the midst of designing an OR which will be fed by a normal and a critical branch panelboard with GFCI breakers. For the first time ever, I am wiring the critical branch panel with regular conduit and wire as opposed to MI cable. This I justify by the 2014 NEC's divorcing of the critical branch from Article 700. I'm comfortable with it because I've long suspected MI cable of being a huge waste of money.

This is however an opinion not supported with empirical evidence. And when one goes to find information on the merits of MI cable, one finds a slew of articles by it's one and only one manufacturer in the US, Pytrotenax. Is anyone familiar with a white paper or other resource which objectively discusses the benefits or lack thereof of MI cable?

Thanks,

Mike

 

[roger]

. I'm comfortable with it because I've long suspected MI cable of being a huge waste of money.


Thanks,

Mike

And you are right. I've been wiring OR's, Triage Rooms, CT"s, Linear Accelerators, PACU's, etc... for 40 years and have never used MI cable in any of them.

Not only is it a huge waste of money, IMO, it's an antiquated wiring method.


Roger

 

[GoldDigger]

And you are right. I've been wiring OR's, Triage Rooms, CT"s, Linear Accelerators, PACU's, etc... for 40 years and have never used MI cable in any of them.

Not only is it a huge waste of money, IMO, it's an antiquated wiring method.


Roger

But if the NEC requires a high degree of fire resistance for the circuit, you may be able to use wire in raceway, but you would then have to encase the raceway in 2" of concrete.
The OP is asserting that fire resistance is not really needed for his application, just protection from physical damage.

 

[roger]

But if the NEC requires a high degree of fire resistance for the circuit, you may be able to use wire in raceway, but you would then have to encase the raceway in 2" of concrete.

Please tell me where this would be required and then tell me you have seen OR wiring encased in concrete up the walls and overhead to power drops?

The OP is asserting that fire resistance is not really needed for his application,

The OP is correct, it is not needed for this application

Just protection from physical damage.

Which is always the case, it is not a new requirement.

The 2014 simply removed the term Emergency System, it didn't really change anything else.

Roger

 

[gadfly56]

But if the NEC requires a high degree of fire resistance for the circuit, you may be able to use wire in raceway, but you would then have to encase the raceway in 2" of concrete.
The OP is asserting that fire resistance is not really needed for his application, just protection from physical damage.

Or use Windy City's 712100LSZH CI riser cable. It's not on their web site, but I have a cut sheet for it. It comes in only one flavor, 14-2. Alternatively there is their CIC cable, listed FPL, part number 728100LSZH-S. It goes in EMT.

 

[GoldDigger]

Please tell me where this would be required and then tell me you have seen OR wiring encased in concrete up the walls and overhead to power drops?

Fire pump wiring comes to mind first.

 

[gadfly56]

Fire pump wiring comes to mind first.

Ding! ding! ding! We have a winner! AFAIK, if you don't run outside the building or put it in 2" brick or concrete, you're looking at MI for a new install.

 

[don_resqcapt19]

Fire pump wiring comes to mind first.

But the question is about the wiring for an operating room.

 

[GoldDigger]

But the question is about the wiring for an operating room.

And I addressed the general use of MI, not just the operating room case. I did not make that clear enough.

 

[Phil Corso]

MI certainly has its positive applications. I once had to install 11,000 feet for a modernization project for a US Gypsum plant!

Another unbeatable application is its use for power and instrument wiring associated on installations on the burner-face of boilers!

Regards, Phil Corso

 

[GoldDigger]

MI certainly has its positive applications. I once had to install 11,000 feet for a modernization project for a US Gypsum plant!

Another unbeatable application is its use for power and instrument wiring associated on installations on the burner-face of boilers!

Regards, Phil Corso

A great reminder that the insulation on conventional wiring goes bad causing shorts long before the copper conductor or sheath melt.

 

[roger]

Fire pump wiring comes to mind first.

And as Don points out, that has nothing to do with the question of branch circuit wiring in an O.R. or the price of peanut butter, IOW's not relevant to the OP's topic.:roll:

Roger

 

[Phil Corso]

Roger, since when did any comment on this forum have to relate to the OP's original query!:happyno:

In a lighter note, I'm not sure of the point you were making, but at the time of the installation I described, a test was performed on several MI cable sizes. Samples were crushed to about 1/4 of their original OD dimension, and never resulted in neither a conductor-to-conductor, or conductor-to-sheath failure!

Phil