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Author Topic: (How) Can I connect my single-phase distro to a three-phase tie in?  (Read 21328 times)

Neil Sakaitis

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #30 on: January 22, 2016, 01:36:16 pm »

Thanks for the reply Mark !! Yes I am aware that if I hook up to a 3-phase 100A, and only use 2 legs, each leg will have 100A capacity totaling 200A. Since I am thinking of adding a main breaker to my distro (if space permits), I need to figure out what size main breaker to go with, based on feeder size and 16 installed breakers. So to help clarify my area of focus where I am looking for feedback:

1) Feeder is a #2 SC, Distro has Series 16 Cams, with 8 X 15A and 8 X 20A breakers. What size main breaker does one install. Assuming correct temperature for feeder, rating says 190A. A double 100A main would be too small, as I have more capacity on the feeder (assuming temp ok). A double 200A would bypass the rating of the cable by 10A, and odds are not recommended. So what is the in-between breaker size to go with for distro mains (I wish they sold a double 190A) ??

2) I currently have 8 X 15A and 8 X 20A breakers and outlets on the distro. If I maxed (which I usually don't) each circuit, that would total 280A across both legs on single phase (140A per leg if balanced). My feeder can handle that, so want to make sure my main breaker is sized properly so I can take advantage of all 16 circuits presently installed. Perhaps if my max is 140A on breakers per leg, a double 150A for main breaker might be appropriate here.

3) Chassis ground. Some have suggested that my ground in my distro right now is only between outlet and chassis. If I am to run a better ground connection between CAM lug and chassis, what size wire should I use internally (#2 SC ?), and is it simply a matter of tapping that wire onto the metal lining of the inside case ?

Thank you for your time !!

Neil

Neil,

Are you perhaps overlooking the fact that each of the feeder cables and cams is individually rated?  With a 100 amp single-phase (a/k/a split-phase) service, both of your hot leg #2 feeder cables will carry 100 amps safely. At the distro (where there typically would be a double pole 100 amp OCPD), you have available 200 amps of 120 volt AC power.  (Two legs of 100 amp service.)  From some of your comments, you appear to be doubling the needed ampacity of the feeder.
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Mark Cadwallader

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #31 on: January 22, 2016, 02:11:14 pm »

Neil, if I am reading your posts correctly, you have 16 individual #12 (or #14) AWG conductors stuffed into each of the lugs on the cam connectors. (Eight from the original construction, and eight more that you added.)  If so, and with all due respect, I would not personnally want to use your distro. I recognize that you have not had any problems to date, but there is a lot of energy present inside there. The lugs are not designed for that use. Bus bars are designed for attaching individual wires.

I respectfully suggest that rather than trying to retrofit your distro you should get a well-designed, UL or ETA listed distro of appropriate size for your needs.  If you don't use it very often, rental might be a more cost-effective solution than buying a distro. If you decide to keep using your distro, you should review your insurance coverages (liability, home, and life insurance) with your agent.
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Neil Sakaitis

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #32 on: January 22, 2016, 02:31:57 pm »

Yup, agreed, and already a step ahead of you, based on recommendations here, I will be ordered three Square D 264108 double pole 8 branch connecting blocks. The 8 branch blocks will allow me to feed the 2 legs to each group of 8 breakers, and the 2 remaining double pole 8 branch will allow me to feed up to 16 neutral and ground connections to the outlets. Great idea, this takes care of the branch wiring. Sad that a professional distro company was selling this stuff like this, there are probably dozens of guys out there with the same setup as me.

So that takes care of that. Now for the ground. Assuming I have a block in place, can I simply use a #12 or #14 off the block and tapped onto the case chassis, or do I need to have a #2 SC coming off the CAM lug to the chassis ?

With those things out of the way, I just have to hunt down someone who sells a 1U panel with a cutout for a main breaker. Most main breaker panels I see from the likes of Motion are 3U and does not fit in my setup.

On a side note, if you take a look at the distros coming from PSS (ampshop), at least the distros they show on their site, there is no main breaker, only the individual circuits are breakered. So no surprise that there is none on mine when I ordered it way back when.

Thanks for all your help (and honesty), much appreciated !!

Neil
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Neil Sakaitis

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #33 on: January 22, 2016, 02:34:51 pm »

And just to be sure, is it ok to use a couple pieces of #2 SC from the CAM lugs to the distro blocks, or do I need to go get some short length of #2 solid copper for the jumps (which will probably be harder to work with in such a tight space).

Thanks
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Tim McCulloch

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #34 on: January 22, 2016, 02:41:31 pm »

And just to be sure, is it ok to use a couple pieces of #2 SC from the CAM lugs to the distro blocks, or do I need to go get some short length of #2 solid copper for the jumps (which will probably be harder to work with in such a tight space).

Thanks

#2 THNN or similar.  Type SC is rated only for portable use.
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Stephen Swaffer

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #35 on: January 22, 2016, 03:24:21 pm »

The distro blocks I mentioned are a UL listed method for connecting many small wire to a larger source-easier to make sure it is right than a bus bar-they usually have an ampacity marked on them so no "engineering" involved.

As for the ground, you could use either another distro block, or change out the lug to one that has 2 holes or is designed for multiple condctors.  The size of the ground conductors depends on the breaker protecting the distro-so I would size it according to the ampacity of your feeders and always use a proper breaker ahead of it.  So, if you are using 100 amps, #8 is sufficient, if you are using 200 amps I would use #4.

FWIW, the actual allowable conductors for those is impossible to tell from your pictures.  They should be stamped on the side with the allowable conductors.  So, for instance, they might say #10-250mcm and any conductor in that range is fine.  IF, they say something like 2-#6-4/0 then you could actually put two conductors of the same material (2 copper or 2 al-but NOT one AL and one Cu) in one-then you could use one to bond the chassis and one to go to your ground distro block.
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Mark Cadwallader

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #36 on: January 22, 2016, 03:49:59 pm »


(Snip)

When I use my distro at home, I know the limits of my cable, and end up cabling it directly (temporarily) to a SqD breaker within my home panel, for 1 specific event that takes a lot of juice. Assuming that my breaker is sized correctly to the feeder cable, I think I should be fine there without needing an expensive breakered disconnect, as the main (sized) breaker in my panel becomes that disconnect for me.

(Snip)

Neil

The above statement makes me ask: How do you tie in at home?  Do you have an unused dual pole breaker (OCPD) that you tie to?  What is the ampere rating on that breaker?  Are you using the #2 SC feeder cable for the tie-in?
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Neil Sakaitis

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #37 on: January 22, 2016, 04:33:24 pm »

Mark, I see where you are going with this question, and can anticipate the answer :-) In all honesty, since it is up temporarily for Halloween in my closed basement, yes, I tie the SC feeder straight into the home panel in an unused 100A dual pole breaker.

My guess, the proper way to do this would be to use solid copper in a conduit from the main home panel/breaker to a dedicated CAM box, with the 100A disconnect breaker in the home panel to control the CAM box, and then my SC would tie into the CAM box. But since this is a home, I thought it would be overkill to have a CAM box screwed onto my basement/cinema room wall for a whole 2 days (Halloween) worth of use.

But I hear you on the whole code, liability, insurance thing. 10 years running, and always cross check my wiring. Please don't scold me :-)

Already have my distro apart after this conversation, and figuring out where I will be mounting my distro blocks. Ordered 3 double pole 1 X 8 SqD, one double pole for both legs, 8 feeds to 8 breakers each, and then 1 double pole each for 16 feeds of neutral and ground to the outlets.

Hoping it is ok to screw thru the case and metal lining to be able to mount the blocks solidly.

For the ground, can I purchase a replacement lug only for the ground CAM, without replacing the entire CAM panel mount, giving me a 2 wire connection, one for the distro block and one for the chassis ground ??

The other option I have to look into, is getting a 2 X 8 distro block for the ground, that allows 2 connections on the feeder side. This way I can go from CAM to distro block and back out to chassis for the ground.

Thanks

The above statement makes me ask: How do you tie in at home?  Do you have an unused dual pole breaker (OCPD) that you tie to?  What is the ampere rating on that breaker?  Are you using the #2 SC feeder cable for the tie-in?
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Neil Sakaitis

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #38 on: January 22, 2016, 05:49:47 pm »

OK,

All distro blocks ordered, and figured it all out. I ordered 1 double pole 1-In x 8-Out which covers me for the 2 legs, each pole feeding 8 breakers with a mix of 15A and 20A plugs (16 total). Then I ordered 1 double pole 2-In X 8-Out, which allows me to jump both poles for the Neutral and Ground to give me 16 outs (for my 16 outlets), and a remaining jump to chassis ground. All done with SqD 9080 blocks.

Thanks guys for this discussion, really cleared things up, and now my CAM and internal wiring will be much better and a better ground to boot.

I am of course still stuck for where to put that main breaker. Assuming that my power blocks won't come up too high, I have approx. 1.5U worth of blank space in my rack to house a main breaker. Sadly a 2U won't fit and a 1U will probably be too short for a main double breaker.

Do you guys know if Motion or PSS sells main breaker panels that small ?? If not I will have to go with an external breakered disconnect, no choice.

Thanks
« Last Edit: January 22, 2016, 05:52:49 pm by Neil Sakaitis »
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Mark Cadwallader

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #39 on: January 22, 2016, 05:59:53 pm »

Sounds like a heckuva Holloween party/haunted house.  And I can well imagine that somewhere out there folks are doing similar things with much scarier home-built contraptions ....
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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #39 on: January 22, 2016, 05:59:53 pm »


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