Hodding feeder

gafftapegreenia

gafftapegreenia

CBMod
CB Mods
[MOD NOTE: This post was originally a comment to the wiki entry rack jumpers, but was moved here for broader exposure.]

It seems common that conductors are banded together, as I've seen a lot of it in Milwaukee. Good to know it's technically bad, but is banding something that is "field practice" and thus people do it anyway, or what?
 
Last edited by a moderator:
gafftapegreenia said:
MOD NOTE: This post was originally a comment to the wiki entry rack jumpers, but was moved here for broader exposure.

It seems common that conductors are banded together, as I've seen a lot of it in Milwaukee. Good to know it's technically bad, but is banding something that is "field practice" and thus people do it anyway, or what?
Click to expand...

The severity of the "banding infraction" depends on the gauge and its rating vs. common usage.

Gauge/Temp rating--------------------Rating---------------Common usage

#2AWG/90C--------------------------190A-----------------100A
#2/0AWG/90C------------------------300A-----------------200A
#4/0AWG/90C------------------------405A-----------------400A

If these cables were derated to the ampacity of a multiconductor cable with four current-carrying conductors, their ampacity would be:

#2 AWG--------------------152A
#2/0 AWG------------------240A
#4/0 AWG------------------324A

So, you can see that banding #2 or #2/0 still allows the common usage ampacity to stay within the rating, but banding #4/0 does not.

ST
 
How tightly banded are we talking about here? In regards to NEC derating, is the banding issue concerned with single conductors grouped within an outer jacket, or in a conduit, etc.? Since a banded feeder is still generally subject to free air circulation, is the derating really a concern? I wouldn't think a feeder would be banded very tightly or that often over it's length to keep it as manageable as possible. (5) #4/0's are a beast unbanded, much less banded tightly.
 
epimetheus said:
How tightly banded are we talking about here? In regards to NEC derating, is the banding issue concerned with single conductors grouped within an outer jacket, or in a conduit, etc.? Since a banded feeder is still generally subject to free air circulation, is the derating really a concern? I wouldn't think a feeder would be banded very tightly or that often over it's length to keep it as manageable as possible. (5) #4/0's are a beast unbanded, much less banded tightly.
Click to expand...

If the conductors are in contact over any portion of their length, they will inter-heat. Therefore they need to be derated if that is the case. Don't forget that these conductors use their free-air rating, which (especially in the case of 4/0) leaves no margin.

ST
 
Just in the interest of fun while we are discussing hodding....

Say you are pulling 3 400amp company switches with 4/0 to feed dimmer beach and all the feeder is single loose cables. What order should the cables lay on the ground and why?
 
gafftapegreenia, see also the thread 1 Wire vs 5 Wire.

-----

STEVETERRY said:
... So, you can see that banding #2 or #2/0 still allows the common usage ampacity to stay within the rating, but banding #4/0 does not.
Click to expand...

I counter that the hodding of 4/0 cables 10' or less, for the sole purpose of supplying downstream racks, IS an acceptable practice. Production electricians will almost always put the heaviest-loaded rack first in the chain, thus even with de-rating factor, a banded set of 4/0 is within limits.

Now whether it's acceptable to supply the first rack with 400A 4/0, and then use 2/0 rack jumpers (banded or not) to feed additional racks is an entirely different question.

Since I started typing this before any of the above responses...
From ESTA_FeederCableDraft_BSRE1-18-1r13.pdf (did this ever make it to ANSI standard?):
When feeder cables current carrying conductors are bundled, triped, harnessed; triplexed or in a triangular or square configuration; or stacked; or less than one cable diameter from any other adjacent object or cable(s) all of the conductors that are bundled, triped, harnessed; triplexed, or in a triangular or square configuration; or stacked; or less than one cable diameter from any other adjacent object or cable(s) shall be counted in the ampacity calculation of Table 3.4.3.
Click to expand...
STEVETERRY, can you explain why your numbers (presumably taken from NEC 2011 Tables 400.5(A)(2) and 400.5(A)(3), are radically different from Table 3.4.3 [which I will not quote because mine is a draft copy]? The table in the ESTA document seems overly conservative in light of the above.

-----
Footer said:
Just in the interest of fun while we are discussing hodding....

Say you are pulling 3 400amp company switches with 4/0 to feed dimmer beach and all the feeder is single loose cables. What order should the cables lay on the ground and why?
Click to expand...
Kyle, asked and answered:
Footer said:
Just to tack onto this... say you are running 4 sets of feeders for "the big rock show", how do you run them? All neutrals together, grounds together, phases together or do you do ABCNG?

And... the final question.... when you run the feeder and have some left over, what should you do with the excess.
Click to expand...
 
Last edited:
derekleffew said:
I counter that the hodding of 4/0 cables 10' or less, for the sole purpose of supplying downstream racks, IS an acceptable practice. Production electricians will almost always put the heaviest-loaded rack first in the chain, thus even with de-rating factor, a banded set of 4/0 is within limits.

Now whether it's acceptable to supply the first rack with 400A 4/0, and then use 2/0 rack jumpers (banded or not) to feed additional racks is an entirely different question.

Since I started typing this before any of the above responses...
From ESTA_FeederCableDraft_BSRE1-18-1r13.pdf (did this ever make it to ANSI standard?):
STEVETERRY, can you explain why your numbers (presumably taken from NEC 2011 Tables 400.5(A)(2) and 400.5(A)(3), are radically different from Table 3.4.3 [which I will not quote because mine is a draft copy]? The table in the ESTA document seems overly conservative in light of the above.
Click to expand...

And you could no doubt make that comment in the next public review. :) FYI, the document will be very different when it comes out for that review.

ST
 
Last edited:
derekleffew said:
Now whether it's acceptable to supply the first rack with 400A 4/0, and then use 2/0 rack jumpers (banded or not) to feed additional racks is an entirely different question.
Click to expand...

Under certain "tap rule" conditions, yes:

1. 20' or less in length, do not penetrate walls or floors, protected from physical damage, supported 7' above floor except at terminations, are not bundled, are in unbroken lengths (NEC 520.53(H)(4).
2. Device being fed from the rack jumps has a single main breaker that limits the current to the ampacity of the 2/0 or lower (NEC 520.53(H)(4) .


While we are at it on this discussion, two important definitions from Article 520:

Bundled. Cables or conductors that are tied, wrapped, taped, or otherwise periodically bound together.

Grouped. Cables or conductors positioned adjacent to one another but not in continuous contact with each other.

ST
 
Last edited by a moderator:
Footer said:
Just in the interest of fun while we are discussing hodding....

Say you are pulling 3 400amp company switches with 4/0 to feed dimmer beach and all the feeder is single loose cables. What order should the cables lay on the ground and why?
Click to expand...

You should lay your cable so that the hot are in the middle with neutral and ground laying on the far outsides (ground, hots, neutrals).

Ok I was going to post this in the QOTD section but two neutrals must be run when you cannot go to the next largest wire awg in a 3 phase circuit running a single phase load. (sorry for the bad explanation, let me clarify). You run your 400 amp feed into your 400a dimmer (400 amps per leg times 3). In a scene you are running all of your lights on just one leg (your neutral is now maxed out at 400a 100% load) next scene you turn on everything on your second leg along with your first leg you are now over loading your neutral (about 130% load) also even if you figured you would be smart and run 2 neutrals but one is shorter than the other you could still overload your cable. This is especially true when doubling your hot legs though not a common practice for temporary power due to using 2 smaller racks over one really big one or a insane power run where you have a large voltage loss. When voltage drops amperage goes up.
 
TimMiller said:
You should lay your cable so that the hot are in the middle with neutral and ground laying on the far outsides (ground, hots, neutrals).

Ok I was going to post this in the QOTD section but two neutrals must be run when you cannot go to the next largest wire awg in a 3 phase circuit running a single phase load. (sorry for the bad explanation, let me clarify). You run your 400 amp feed into your 400a dimmer (400 amps per leg times 3). In a scene you are running all of your lights on just one leg (your neutral is now maxed out at 400a 100% load) next scene you turn on everything on your second leg along with your first leg you are now over loading your neutral (about 130% load) also even if you figured you would be smart and run 2 neutrals but one is shorter than the other you could still overload your cable. This is especially true when doubling your hot legs though not a common practice for temporary power due to using 2 smaller racks over one really big one or a insane power run where you have a large voltage loss. When voltage drops amperage goes up.
Click to expand...

Err....not exactly.

The 130% neutral overcurrent occurs on a three-phase feeder when certain combinations of phase control dimmers are run at less than full. This is due to the chopped waveform and triplen harmonics.

Also, when voltage drops, so does current. Lamps have a wattage for a rated voltage. Less voltage, less power, less current.

If this were not the case, how could you dim a load?


ST
 
TimMiller said:
You should lay your cable so that the hot are in the middle with neutral and ground laying on the far outsides (ground, hots, neutrals).
Click to expand...

So question then, why does it come out of my company switch G-N-N-1-2-3? I dont really work tons with this kind of distribution so Im just wondering, if it is correct to run them G-1-2-3-N, why not have it come out of the switch like that? (Maybe more of a switch design question than a power question)
 
shiben said:
So question then, why does it come out of my company switch G-N-N-1-2-3? I dont really work tons with this kind of distribution so Im just wondering, if it is correct to run them G-1-2-3-N, why not have it come out of the switch like that? (Maybe more of a switch design question than a power question)
Click to expand...

It has to do with the way you connect your feeder. While running cable in that orientation is important, it is MUCH more important to connect your feeder in the proper order - G-N, then your hots. I don't know if there's a code requirement for them to be laid out like this on racks, but even an inexperienced electrician who didn't know this would be more likely to connect feeder from left to right.
 
The concept of having ground and neutral on the outside of the cable lay is that they are the most likely to get cut into by accident. Never had it happen, but if you end up with exposed wire it's better that it is a low potential. Not sure how many actually do that. Back in the days, we had a cart with a big wire wheel to store the feeder. You would grab the male cams and head toward the switch. Although the conductors were not bound, they would spool off together. At the end of the night, you would grab a couple of people to help and you would spool them back on. I will admit, I did not pay much attention as to which was which on the lay, as they all were black.

Now, as for moving that cart.... :angryoldman: well, it was a long time ago!
 
In Hollywood, we always lay cable in the order of either:
G-N-H-H-(H)
H-H-(H)-N-G
One or the other, due to different distro boxes in rental shops. We always take care-neatness counts- to keep them correctly laid. This makes trouble shooting/following a line easier.
When doing the tie in, we always connect:
G-N-H's
Disconnect:
H's-N-G.
Under ALL circumstances: "Play it Hot!", meaning treat them as if they have been energized.
We also use a non code (fire marshals don't recognize it, so we do tape as well) rope knot identifier system using the cable tie as the 'lines':
G: 2 knots using two lines
N: 1 knot using two lines
H Red: 1 knot using one line
H Black: 2 knots using one line
H Blue: zero knots on either line.
This makes checking them in the dark much easier.
Also, back then, we used to have tractor genie rigs with spools.
 
Last edited:
Gern said:
...We also use a non code (fire marshals don't recognize it, so we do tape as well) rope knot identifier system using the cable tie as the 'lines':
G: 2 knots using two lines
N: 1 knot using two lines
H Red: 1 knot using one line
H Black: 2 knots using one line
H Blue: zero knots on either line.
This makes checking them in the dark much easier.
Also, back then, we used to have tractor genie rigs with spools.
Click to expand...
Gee Gern, where were you during this thread: http://www.controlbooth.com/forums/lighting-electrics/25180-knots-feeder-cable.html ?:)
 
So, If I am reading this correctly, (and if I have been taught correctly).
If I have bundled 5 wire feeder cable, (Say 2/0 or 4/0) I believe I am required to De-rate said cable assembly by 20%, per 400.5 (A)(3)?
Is that how the "code wizards" here agree?

Also, if this is true, wouldn't it technically require a de-rating if the feeder cables were to touch each other along their entire length, like in all those pretty dimmer beach photos that keep showing up on Facebook?

Got in a discussion on Facebook, and wanted to make sure I wasn't wrong, or making it up.
Thanks,
 
You must log in or register to reply here.

Similar threads

L
The Remarkable Journey of DyLOS
Replies
0
Views
587
Larry Beck
L
R
Is this cable suitable for???
Replies
3
Views
2K
TimMc
TimMc
CHAUVET Professional
Working Washes
Replies
0
Views
2K
CHAUVET Professional
CHAUVET Professional
CHAUVET Professional
Michael Stiller: Interactive Light
Replies
0
Views
2K
CHAUVET Professional
CHAUVET Professional
derekleffew
rack jumpers
Replies
0
Views
1K
derekleffew
derekleffew

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)
Back