500MCM or 600MCM?

[hugop973]

Hi, I have a question about handling 500MCM and 600MCM cable, CU.
Can you tell me which one is easier and/or preferred by contractors.

Thanks

 

[dpc]

Is this a trick question? Smaller is always cheaper and easier to handle, so 500 kcmil would be preferred, assuming it is large enough, of course. It will also be more widely available in most cases. 600 kcmil is a less common size.

Of course they'd rather use aluminum instead of copper.

David Castor

http://www.cvoes.com

 

[magoo2]

600 is not a standard size although the cable manufacturers can supply it. 500 is a common size and would be an off the shelf item.

As dpc says, aluminum is preferred because of weight and cost. Bump it up to 750 or 1000 if you need the higher ampacity.

 

[hugop973]

I was told by a rep of Okonite that 600MCM is easier to handle because it has more strands.
If you see table 8 of NEC, For 500MCM the number of strands is 37 and the overall diameter 0.813 inches.
For 600MCM the number of strands is 61 strands and the overall diameter is 0.893.
I'm not concerned about the price, I know that 500MCM cable is cheaper.

 

[dpc]

So it was a trick question....

If you don't need the ampacity of the 600 kcmil, I would buy 500 kcmil and let the electricians complain. They will complain no matter what you buy.

The increased stranding could make it easier to handle, but it will still be heavier and increase the conduit fill. You didn't give us the voltage, but if it is 15 kV cable, the increased stranding of the conductor won't make as much difference in flexibility as you might think - until it is stripped anyway.

If it is 15 kV, they will probably also complain about how much harder it is to strip Okonite compared to other brands.


David Castor

http://www.cvoes.com

 

[waross]

I've finally stopped laughing but I'm still having attacks of sudden uncontrolled laughter.
I would be laughing as I walked away from that salesman.
I had another attack of sudden mirth when I thought of the probable reaction of a cable crew when it was explained to them that they would be installing 600MCM because it was so much easier than 500 MCM.
Bt the way, do you have an internet reference to Okonite 600 MCM cable. I just spent 1/2 hour and I can't find a listing for any 600 MCM Okonite cable at any voltage.
But, if more strands equates to easier installations and price is no object, consider Diesel Electric Locomotive cable, DEL or locomotive cable. At 1325 strands and 535.3 MCM it may be just what you want.
I'm being bad here. I have installed both 535 DEL and 500 MCM building cables and I wouldn't choose DEL unless I had to. I didn't find 535 MCM DEL particularly easier than 37 strand 500 MCM. It has its own particular challenges.
grin

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Careful, there are a lot of things you cannot use DLO cable for...

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[alehman]

I tend to use a fair amount of 600 for low voltage because for common circuit sizes such as 1200 or 1600A I can use one fewer sets. Electricians don't like it, but it seems to be readily available.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[EricAXEWC]

jraef - can you explain further what it can't be used for? Most of the DLO I've seen is UL listed 2kV RHH/RHW-2, I always thought of it as pretty "flexible" in terms of allowed usage.

 

[resqcapt19]

Eric,
As long as it is the dual listed product there is no issues using DLO/RHH/RHW in NEC applications. There is a lot of DLO available that does not have the RHH/RHW listing and those products cannot be used in NEC applications. The same is true of welding cable, most is listed only as welding cable and cannot be used for NEC applications, but like the DLO some is dual listed as RHH/RHW.

 

[Beardude]

In LV situations where we needed 600 MCM we'd usually "double-up" #4/0 instead since it was always readily available locally. Usually the same sized conduit could be used or we'd have to go up one trade size of conduit depending on insulation type, etc.

 

[jraef]

There are no set-screw type mechanical lugs I know of that are rated for DLO. I've heard there are / was a saddle clamp type of lug that was listed, but it may have been pulled from the market. You should therefore ONLY use compression lugs and they must be specifically listed for DLO and used with a die that impresses a code saying it was the right kind of die. So you cannot use DLO in applications where the terminations can only be done with mechanical lugs, such as circuit breakers or contactors that have built-in mechanical lugs that cannot be removed for compression lug terminations.

Sizes under 1/0 are not CT (cable tray) rated.

Although it's technically OK to pull properly listed DLO in conduit, there is no amount of lube in the world that makes that easy. The jacket sticks to everything and you can't get the lube to follow it for very long. I've had to do it, I don't want to ever again.

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[dpc]

Regarding DLO terminations - there is a change in 2011 NEC requiring that connectors and terminals used for conductors more finely stranded than Class B and Class C must now be specifically marked for the specific conductor class. See Article 110.14.

Just fyi.



David Castor

http://www.cvoes.com

 

[waross]

Hi hugop973;
I was responding to the salesman's statement:
"I was told by a rep of Okonite that 600MCM is easier to handle because it has more strands."
Try selling that to a cable crew.
My point was that the extra strands in 600 MCM vs. 500 MCM do not really make 600 easier to work with. A lot of the work with cable that size is done with pullers of some type. However there is often a lot of bull work involved and the extra weight of the 600 MCM is, well, extra weight to handle. Even though there are more strands, there is still 20% greater cross sectional area to bend.
DLO is very flexible and in both my experience and jraef's the extra flexibility is not the only consideration when it comes to pulling ease.


Bill
--------------------
"Why not the best?"
Jimmy Carter