Need MI Cable

[mkgrady]

I'm bidding a hospital boiler room retrofit job. The only thing unusual in it for me is a requirement for MI cable.

I need to find a quote for about a 50 foot run of MI cable to go from an existing MDP to a new 45 KVA dry transformer. The run is 3 #4 copper and a #8 ground ( I thought the ground was the jacket). I also need to find a quote for the terminations or have them factory installed. I don't have any experience with MI cable but I have extensive experience in installing MV cable, including hand tape, so I figure I can figure out how to terminate it. I can't seem to find a supplier that sells the cable or the terminations. Anybody have a source for this?

 

[Dennis Alwon]

I am sure your supplier can get it. I also think that Iwire (Bob) has worked with this stuff.

 

[mkgrady]

I am sure your supplier can get it. I also think that Iwire (Bob) has worked with this stuff.

The first two suppliers were no help. The third one I called had a written quote to me in a couple of hours.

 

[kbsparky]

How much did they quote you for that wire (inquiring minds...)?

 

[iwire]

I am sure your supplier can get it. I also think that Iwire (Bob) has worked with this stuff.

I have helped pull some big MI and I have terminated small MI (10/4)

The terminations came as a kit with all the parts and great instructions.

I know for the bigger stuff we had a power tool that would peel off the copper jacket.

I have never had to purchase it or the terminations so I am no help on that part.

 

[iwire]

Here are some pics of MI for those that have not seen it. I took these pictures but it is not my work. This work was done by IBEW 103 guys and it was quite a lot of work installing this in a large existing hospital.

 

[cdslotz]

That looks good. It also looks expensive.
Where in a hospital is MI required?
I've seen it for special industrial installs, and have used it on fire pumps.

 

[Twoskinsoneman]

and a #8 ground ( I thought the ground was the jacket)

I'm really no help but thought I would post this about the EGC...

332.108 Equipment Grounding Conductor. Where the
outer sheath is made of copper, it shall provide an adequate
path to serve as an equipment grounding conductor. Where
the outer sheath is made of steel, a separate equipment
grounding conductor shall be provided.

 

[Fulthrotl]

That looks good. It also looks expensive.
Where in a hospital is MI required?
I've seen it for special industrial installs, and have used it on fire pumps.

that's interesting. i've never worked with it, nor seen an install
in person on the left coast... i've seen references to MI cable installs in the
NEC, and thought it was something grandfathered in...

and yeah, looking at the install, i don't want to think how much of a pain
putting that in and making it look nice would amount to.

 

[John120/240]

What condition makes MI cable necessary ? In Iwire's picture he says it is a hospital.

Inquiring minds want to know.

 

[Fulthrotl]

What condition makes MI cable necessary ? In Iwire's picture he says it is a hospital.

Inquiring minds want to know.

http://en.wikipedia.org/wiki/Mineral-insulated_copper-clad_cable

 

[masterinbama]

Here are some pics of MI for those that have not seen it. I took these pictures but it is not my work. This work was done by IBEW 103 guys and it was quite a lot of work installing this in a large existing hospital.

That looks like single conductor MI cable. Notice the non metallic plate where they enter the panel board.

I have never done a complete install but did relocate some from one equipment room back 50' or so to a new electrical room in a local hospital. Long runs through existing structures has got to be a booger.

 

[iwire]

That looks like single conductor MI cable. Notice the non metallic plate where they enter the panel board.

It is single conductor, each group of four is a feeder.

The plate is brass or bronze, metallic but non-ferrous. The steel enclosure is cut out under the plate.

 

[masterinbama]

It is single conductor, each group of four is a feeder.

The plate is brass or bronze, metallic but non-ferrous. The steel enclosure is cut out under the plate.

Thanks I can see that now. Did some 400HZ with single conductors in cable tray. The terminations came with a phenolic plate for panel entry. I suppose with MI maintaining ground continuity is tantamount.


Come to think of it, I think the plates were part of the motor generator.

 

[mkgrady]

I'm told it is used where it is worth it to not have a fire damage the circuit. I understand it can be in a fire a couple of hours without damage.

The quote is for $22.55 per foot. The terminations are $255 for each end plus the cost of a three hole brass plate.

If I get the job I will be working on figuring out how to terminate the cable.

 

[weressl]

I'm told it is used where it is worth it to not have a fire damage the circuit. I understand it can be in a fire a couple of hours without damage.

In the meantime the panels of the installation on the photo example would be gone. There gotta be a better explanation for that installation.

 

[Cow]

In the meantime the panels of the installation on the photo example would be gone. There gotta be a better explanation for that installation.

Yeah, I don't get it. It's installed right next to EMT conduit too....?

So what's the point of MI?

 

[cdslotz]

That gear could be in a fire rated room and the MI feeders go out of that room to smoke fans or something.

 

[iwire]

In the meantime the panels of the installation on the photo example would be gone. There gotta be a better explanation for that installation.

No, that is the explanation.

The room is fire rated but these cables leave the room and travel through the ceilings of the hospital to other fire rated rooms.

 

[weressl]

No, that is the explanation.

The room is fire rated but these cables leave the room and travel through the ceilings of the hospital to other fire rated rooms.

Do you mean to say the the room - where the pictures are taken - is NOT fire rated but travel through the ceilings of the hospital to other rooms that ARE fire rated? If that is the case it would have been more cost effective to make the conversion AT the fire rating boundary. Just wondering what type of fire rated equipment would supply the panel feeders.