"Maximum Cables Per Phase"

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infinity

infinity

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Can anyone explain this notation in a distribution board? The lug has 4 barrels and can accept 4 conductors.

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defies logic does it not ? only possible thing I can think of would be addressing 312.6(A) or(B)
 
augie47 said:
defies logic does it not ? only possible thing I can think of would be addressing 312.6(A) or(B)
Click to expand...

Why would a piece of equipment come with factory quad lugs, if it isn't meant for more than 3 cables per phase?

I could understand if the ampacity is limited to the equivalent of (3) 500 kcmil per phase, i.e. 1140A. But I can't see a reason why you should be forbidden from using (4) 300 kcmil per phase to achieve the same ampacity, other than "the sticker says so". In fact, at least in concept, that would help the situation, because the heat distribution would be closer to uniform, and the total connected cable weight would be less. But "the sticker says so" is a compelling reason to avoid this practice.

Another situation you might have, is if you needed to use more than 3 wires per phase in order to curtail voltage drop. The ampacity would still be limited to 1140A, but you are desiring to increase the conductor size not to get more amps, but to decrease your circuit ohms. Other than "the sticker says so", the only reason I can see why you wouldn't be able to do this, is if the assembly is listed to withstand a maximum weight of the cables connected.

It might be something you should discuss with the manufacturer, to understand the intent of this rule. That is, if you do get in a situation as one that I described above.
 
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Carultch said:
Why would a piece of equipment come with factory quad lugs, if it isn't meant for more than 3 cables per phase?
Click to expand...


I am guessing that the way the holes for the wires are generally stacked, a 3 hole block is less common and thus more expensive than 4 hole blocks.

-Jon
 
Carultch said:
Why would a piece of equipment come with factory quad lugs, if it isn't meant for more than 3 cables per phase?
Click to expand...

Note that it states (3) 350s which if you were using 312.9(A) would require 10" of bending space where as (4) 350s would require 12". On the other hand (4) 250s would only require the 10".

I'm just throwing it our as one logically possibility. If we knew the dimensions referenced that may or may not make sense.
 
augie47 said:
Note that it states (3) 350s which if you were using 312.9(A) would require 10" of bending space where as (4) 350s would require 12". On the other hand (4) 250s would only require the 10".

I'm just throwing it our as one logically possibility. If we knew the dimensions referenced that may or may not make sense.
Click to expand...


Is bending space a function of the number of cables per phase? If so, how? I thought bending radius was just a function of the cable's OD.
 
winnie said:
I am guessing that the way the holes for the wires are generally stacked, a 3 hole block is less common and thus more expensive than 4 hole blocks.

-Jon
Click to expand...

That's a good point too. I can see that being a reason for the hardware existing this way, but I still don't see the underlying reason why the sticker is overriding the lug capacity.
 
Nothing shows up for me using FF. With Chrome there is an icon showing an attached image but the image will not load.
 
ggunn said:
In Safari I just see a negative sign inscribed in a circle.
Click to expand...
That be what I see, using Chrome.

Images have been working on other threads so guessing it is a problem with the image source more so then my browser/machine.

Maybe an issue with a image hosting site?


Add: I tried to open the image in a new tab, got a page with same negative sign on it.

URL of that page was:

https://lh4.googleusercontent.com/5...-NanDRllKg8yQ5YR9xRsjNz-c=s1627-w1627-h920-no

try again I wanted it to display how long that link was but it cut quite a bit of it off:
https://lh4.googleusercontent.com/5...-NanDRllKg8yQ5YR9xRsjNz-c=s1627-w1627-h920-no

Still didn't work, that link was 4 line long on my screen
 
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