Splicing MI Cable

[mstrlucky74]

How is it spliced?

 

[iwire]

How is it spliced?

I have never seen it spliced as the splice and enclosure would have to be just as fire resistant as the cable.

 

[GoldDigger]

How is it spliced?

Very carefully using a manufacturer's spllce kit and with great difficulty.

It is easier to terminate both ends in a box than to do a butt splice.
But it can be done. A very general overview can be seen in this description which applies specifically to MI heat trace cable.

You strip the cable, insert a specifically designed, usually ceramic, bead to maintain spacing and butt splice the conductors, then braze a tube around the conductor splice area to join the sheath together.
All the while keeping moisture and flux from getting at the insulating powder.

 

[mstrlucky74]

Very carefully using a manufacturer's spllce kit and with great difficulty.

It is easier to terminate both ends in a box than to do a butt splice.
But it can be done. A very general overview can be seen in this description which applies specifically to MI heat trace cable.

You strip the cable, insert a specifically designed, usually ceramic, bead to maintain spacing and butt splice the conductors, then braze a tube around the conductor splice area to join the sheath together.
All the while keeping moisture and flux from getting at the insulating powder.

Yes but what if you have a 900' run? Your gonna have to splice if your reels are 500'

 

[infinity]

We have spliced MI cable by setting a box and using standard MI cable terminations.

 

[augie47]

We have spliced MI cable by setting a box and using standard MI cable terminations.

That's the only way I would even attempt it.
I can't imagine the headache in trying to butt splice it.

 

[GoldDigger]

That's the only way I would even attempt it.
I can't imagine the headache in trying to butt splice it.

One estimate I saw was that for an inexperienced person, but with all of the right equipment including a special vise to hold both ends in the correct position, a butt splice could take 2-3 hours.

 

[Fulthrotl]

One estimate I saw was that for an inexperienced person, but with all of the right equipment including a special vise to hold both ends in the correct position, a butt splice could take 2-3 hours.

i would think so, especially after you screw it up the first time......
i wouldn't even think you could splice it. i've never ran across it
in my work, but they used tons of it on warships. i think the mineral
filler was asbestos back then.

 

[mstrlucky74]

We have spliced MI cable by setting a box and using standard MI cable terminations.

Trying to picture what you are saying but what you describe seems like you are terminating only not splicing?

 

[GoldDigger]

Trying to picture what you are saying but what you describe seems like you are terminating only not splicing?

Add a box in the middle of your 900' run, terminate a 400' and a 500' section to the box and join the inner conductors inside the box.
You would have to have a box which maintained whatever rating caused you to need a 900' pull of MI in the first place, of course.
A pure splice would not have that worry, as long as the splicing method and materials are approved by the manufacturer (and the quality of the field work is up to par.)

 

[mstrlucky74]

Add a box in the middle of your 900' run, terminate a 400' and a 500' section to the box and join the inner conductors inside the box.
You would have to have a box which maintained whatever rating caused you to need a 900' pull of MI in the first place, of course.
A pure splice would not have that worry, as long as the splicing method and materials are approved by the manufacturer (and the quality of the field work is up to par.)

Completely got it....sounds just like a regular feeder splice so far. But what would you use to splice the cable inside the box...same stuff as you would use for feeders? Regular Ilsco type splices? Thanks.

 

[GoldDigger]

Completely got it....sounds just like a regular feeder splice so far. But what would you use to splice the cable inside the box...same stuff as you would use for feeders? Regular Ilsco type splices? Thanks.

You would not splice the cable, you would splice the individual inner conductors after terminating the cable to whatever is appropriate. That may end up being terminal blocks, Polaris (TM) connectors or whatever, depending on how the termination kit leaves the inner conductor available and what that inner conductor is.

 

[mstrlucky74]

You would not splice the cable, you would splice the individual inner conductors after terminating the cable to whatever is appropriate. That may end up being terminal blocks, Polaris (TM) connectors or whatever, depending on how the termination kit leaves the inner conductor available and what that inner conductor is.

Yes, I thought so....thanks a lot.

 

[mstrlucky74]

Actually just spoke to n engineer about splicing mi cable for long vertical riser runs and I mentioned the pull box eith termination and then splicing there. He said no they won't use pullboxes...they will do In-Line splices. Does this make sense? Thanks.

 

[GoldDigger]

Actually just spoke to n engineer about splicing mi cable for long vertical riser runs and I mentioned the pull box eith termination and then splicing there. He said no they won't use pullboxes...they will do In-Line splices. Does this make sense? Thanks.

It makes sense if they are experienced in doing such splices, I guess. It will give better mechanical continuity of the outer sheath and may be preferable for that reason. Or it may just cost less. How do you support the weight of MI in a long vertical run anyway??

Like any other splice, I would expect it would have to be located in an accessible part of the vertical run, although maybe not in a box. Hmmm?

 

[mstrlucky74]

It makes sense if they are experienced in doing such splices, I guess. It will give better mechanical continuity of the outer sheath and may be preferable for that reason. Or it may just cost less. How do you support the weight of MI in a long vertical run anyway??

Like any other splice, I would expect it would have to be located in an accessible part of the vertical run, although maybe not in a box. Hmmm?

Support it with strut and strut clamps.

how long would you say it takes to do a 4/0 splice in a riser? One like in the link below. What I don't get is the fire protection kit? Does that go over the splice kit?

http://pentairthermal.com/Images/EN-PyrotenaxMIfactoryfieldsplices-DS-H58429_tcm432-26195.pdf

 

[GoldDigger]

Support it with strut and strut clamps.

how long would you say it takes to do a 4/0 splice in a riser? One like in the link below. What I don't get is the fire protection kit? Does that go over the splice kit?

http://pentairthermal.com/Images/EN-PyrotenaxMIfactoryfieldsplices-DS-H58429_tcm432-26195.pdf

Since the outside structure of the splice apparently does not have exactly the same mechanical and thermal properties as the original uninterrupted sheath, then if you need to maintain the full fire resistance rating of the MI cable, you have to put additional protection (insulation and/or intumescent protective material) around the splice when you are done. Yes.

No idea how long it takes. I would ask the manufacturer's tech reps about that and then see what other input I could get.

 

[mstrlucky74]

Since the outside structure of the splice apparently does not have exactly the same mechanical and thermal properties as the original uninterrupted sheath, then if you need to maintain the full fire resistance rating of the MI cable, you have to put additional protection (insulation and/or intumescent protective material) around the splice when you are done. Yes.

No idea how long it takes. I would ask the manufacturer's tech reps about that and then see what other input I could get.

Thanks

 

[iwire]

Do the job specs that you are estimating allow the splicing of MI cables?

 

[jmellc]

Yes but what if you have a 900' run? Your gonna have to splice if your reels are 500'

As far as I know, most wire or cable can be ordered in 1,000 ft rolls as well as 500 ft. If you have time and know you have 900 ft runs, the 1,000 foot spools would be a much better idea. I think some wire can even be ordered in 2,500 ft lengths but I'm not totally sure of this.