Question about Arktite Plugs and how to split loads..

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jucesanc

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We have a temporary installation that includes three loads: electric heater, 20 hp motor, and some heat tracing.

These will be fed from a common breaker back at some 480V MCC. This 3-phase breaker is 250AT/400AF.

There is a temporary cable that is routed from this breaker out to the field: 4/0 AWG, 4/C, Type W, 90 degrees C, which puts it's ampacity at 260A (NEC 17 Table 310.15(B)(16)).

How do I split the loads from this one cable? Is there some sort of 3-way power cable connector that I can buy? My google search results are not returning anything promising..

We have something onsite with one male arktite plug and two female arkite plugs. It's a 2-way splitter. But I can't find anything like it online.
 
Unless you want to run 4/0 cable to each load, you will need to have branch circuit protection for those smaller circuits. Once you do that, you will have a box that can have separate receptacles for your individual loads.
 
Jraef said:
Unless you want to run 4/0 cable to each load, you will need to have branch circuit protection for those smaller circuits. Once you do that, you will have a box that can have separate receptacles for your individual loads.
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The three branches will have circuit protection. The electric heater and the motor will have OCPDs provided by the manufacturer. For the electric heat trace, we are installing a 480-240/120V xfmr with a fused disconnect.

We're planning to feed these three loads from the one 4/0 cable. I'm just not sure how to go about feeding three 3-phase 480V loads with one 3-phase 480V cable. What equipment do I need to make this happen? Do I route the cable to a box, create a bus, and feed the three loads off of there?
 
jucesanc said:
The three branches will have circuit protection. The electric heater and the motor will have OCPDs provided by the manufacturer. For the electric heat trace, we are installing a 480-240/120V xfmr with a fused disconnect.

We're planning to feed these three loads from the one 4/0 cable. I'm just not sure how to go about feeding three 3-phase 480V loads with one 3-phase 480V cable. What equipment do I need to make this happen? Do I route the cable to a box, create a bus, and feed the three loads off of there?
Click to expand...

Remember that unless you keep the same wire size as the feeder all the way to the downstream OCPDs, you will have to take tap rules into account.
 
GoldDigger said:
Remember that unless you keep the same wire size as the feeder all the way to the downstream OCPDs, you will have to take tap rules into account.
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I was assuming none of the rules applied, mainly because coming out of an MCC, I would assume the distance is more than 25', then using Type W, it is not going to be "suitably protected".

But here is a great compendium of the Tap Rules for you to peruse, jucesanc. See if any of them apply. If not, you are back to what I said. A distribution box with feeder breakers for the smaller loads, or running the 4/0 all the way to each load.
https://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/FeederSecondaryTapRules~20020326.htm
 
Jraef said:
I was assuming none of the rules applied, mainly because coming out of an MCC, I would assume the distance is more than 25', then using Type W, it is not going to be "suitably protected".

But here is a great compendium of the Tap Rules for you to peruse, jucesanc. See if any of them apply. If not, you are back to what I said. A distribution box with feeder breakers for the smaller loads, or running the 4/0 all the way to each load.
https://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/FeederSecondaryTapRules~20020326.htm
Click to expand...


The distance is 1,100 ft.
 
jucesanc said:
We have a temporary installation that includes three loads: electric heater, 20 hp motor, and some heat tracing.

These will be fed from a common breaker back at some 480V MCC. This 3-phase breaker is 250AT/400AF.

There is a temporary cable that is routed from this breaker out to the field: 4/0 AWG, 4/C, Type W, 90 degrees C, which puts it's ampacity at 260A (NEC 17 Table 310.15(B)(16)).

How do I split the loads from this one cable? Is there some sort of 3-way power cable connector that I can buy? My google search results are not returning anything promising..

We have something onsite with one male arktite plug and two female arkite plugs. It's a 2-way splitter. But I can't find anything like it online.
Click to expand...

Couple of items:
Type W ampacities are per Table 400.5.A.2, 75C column. So 4C - 4/0 is 277A. 4C - 3/0 is 243A.

If the cable has not been purchased, consider 3C - 3/0, Type G. Type G has a grounding conductor. So 3C gets you 3 -3/0 and 2 grounding conductors.

Jraef cited "Outside Feeder Tap of Unlimited Length Rule [240.21(B)(5)" - which is good.
And Augie suggested Polaris connectors - which are also good. Get ones that are speced for fine strand conductors (Type W and Type G are fine strand)
At the MCC end, you will also need lugs rated for fine strand.

Consider:
  • Run the 3C-3/0 from the MCC to a location close to the equipment.
  • Terminate in a J-box with Polaris connectors.
  • For output connections, run smaller Type W, or Type G (suitable for each load) from the Polaris connectors to each load. These are the taps. Pick one from 240.21.B.1, 2, or 5. If none of those fit, then as Jraef and Golddigger said, the taps must be full ampacity.
  • Per Table 400.5.A.2, Type G, 3C - 3/0 is 243A. If you haven't bought the cable yet, 3C-3/0 is likely big enough - the load has to calculate less than or equal to 243A.

As for cord and plug - consider:
400A pin and sleeve connectors are freaking huge and expensive. You would need one inlet, and three outlets. Although, the outlets could be significantly smaller, depending on any available tap rules.
If this does not have to be R&R very often, use the Polaris connectors.
 
zbang said:
Or Camloks.
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I thought of them, but I have never used them on multi-conductor cable. Maybe okay, but it would look tacky.

However, single conductor Type W and camlocks for the 1100' run, is an excellent idea.

3C-3/0 is ~3 lbs/ft - 3300 lbs for 1100'. Skid steer, forklifts, chain falls, rigging - :sick:

Type W 3/0 is ~.8 lbs/ft. One could make up sets of color coded jumpers, 100 feet long, 80 lbs each conductor. Still going to want a fork lift and pallets - but single person manageable. Should type wrap the four all together - keeps the Short Circuit impedance down. And since the conductors are touching, still have to use T400.5.A.2, column F - too bad, going to single conductors, not touching, allows column D, 1/0 >> 230A

Yes, the code has a hard time with the single conductors, however, I have never had a AHJ squawk about a temporary installation.

zbang -
Good idea - if the cable is not already purchased
 
If it's really temporary (590-compliant temporary), I'd rent the cable if it wasn't already on hand. Wouldn't even tywrap/band the bundle, just makes it harder to handle, I don't think loose-laying them would have much effect on the impedance. Local conditions apply and all that :D.

Oh, and having assembled arktite (aka russellstoll) connectors, I'll do almost anything to avoid that again.
 
zbang said:
... I don't think loose-laying them would have much effect on the impedance. ....
Click to expand...
My experience is the separation does affect the impedance.
One anecdotal example (about 45 years ago - so I'm a little hazy on the numbers)
And a reference on inductance of parallel conductors - it is nothing I calculate, so I don't have a reference on 3 phase transmission lines.

The issue is not with normal operation voltage drop, but rather effect on short circuit current. The concept is similar to up sizing the EGC for distance to get the CB to trip quicker on Short Circuit.

However, if the cables are not touching, one can use T400.5.A.2, 75C, column D instead of Column F. And that will allow dropping conductor to 1/0.
 
zbang said:
... Oh, and having assembled arktite (aka russellstoll) connectors, I'll do almost anything to avoid that again.
Click to expand...

I have not done any in the 4/0, 400A, pin and sleeve range. But I would still agree.

Biggest I have ever done is C-H, 100A, Pin and sleeve, #4 type G. It was not too bad for a 100' extension cord.

After that, it was power distribution blocks or Polaris connectors in a j-box, or as you suggested, single conductors and cam-loks
 
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