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Author Topic: (How) Can I connect my single-phase distro to a three-phase tie in?  (Read 20870 times)

Mac Kerr

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« Reply #20 on: January 22, 2016, 07:58:46 am »

Is there a way to post pictures here, other than include a link to a hosted picture ? I just found pictures of my distro including a shot of the rear panel all wired up internally, would make for a better conversation if I could include the pics here. In the meantime, will find somewhere to upload it.

At the bottom of the posting window is a button called "Attachments and other options". Click that and you will be able to add up to 5 photos to any post as long as the total size does not exceed 512KB.

Mac
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TJ (Tom) Cornish

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #21 on: January 22, 2016, 09:29:04 am »

Hmm, curious again here, and thanks for pointing me to Motion Labs, seems like they do have Main Breakers on their distro designs. When I was shopping around for distros, like mine (suitcase style), I guess the company assumed I had another breakered disconnect, because in their designs, no main breaker on the distro.

When I had to expand my distro, I opened it up to add a 2nd plate of breakers, and noticed the distro company simply wired all of the breakers with single solid copper straight into the CAMs, so basically the CAM nut ties down all the copper going to the breakers.

Now if I was to figure a way to get a main breaker panel in there, I would assume I would have to use some SC cable internally to jump the CAMS to the main breaker, but then from there, how would one tie 16 breakers worth of copper to the main breaker ??

At that point, I would imagine there is a way to safely get some bus bars in there huh. Again, in my case, it is a suitcase style with metal lining, so might be tough to get bus bars in there.

Any ideas how it is done internally when introducing a main breaker?

Thanks guys !!
Neil, it's good practice to have a main breaker on your distro.  This accomplishes several things:

- it allows you to use the short tap rule without an external breaker - i.e. if you had a 100A breaker in your distro and your feeder cable was 10' or shorter, you could legally tie in to the 400A switch
- If something goes wrong, you have one place to shut off your power, rather than needing to flick a bunch of branch breakers (caveat - you don't want to make a habit of switching your main breaker on or off under load, but in an emergency, it's nice to have)
- It provides a nice way to ensure that all downstream power is indeed off, as with a bunch of branch breakers, something might be missed and still be live, which could be problematic for switching the company switch off, etc.

None of these things are life or death and as others have mentioned, the most important function of a main breaker is to protect the feeder cable itself - something that can only be completely done at the beginning of the feeder and therefore not internal to your distro, but safety in electrical distribution is accomplished with multiple layers of insurance, and having a main breaker on your distro is definitely nice to have.

In your situation, I wouldn't go out of your way to modify your distro.  Doing it yourself is likely worse than not having a main breaker from a liability perspective.  As long as you are using the correct cable - SC and not welding cable or SOOW broken out into individual cams, and you are plugging into a feed that is breakered below the maximum capacity of your downstream equipment, you're in pretty good shape.
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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 #22 on: January 22, 2016, 10:12:58 am »

Loving the feedback, so many people willing to share their best practices and guidelines, great forum !!!

Here are a few shots of my distro, when I first received it. This was the initial panel, which has 8 X 15A circuits with mini breakers. Since I needed more circuits, I have since swapped out the 2U blank panel above it with an 8 X 20A SqD panel. I then split the Edison outlets so I could have a total of 16 circuits. Now keep in mind, I am not using all of them to their full capacity, as I realize that I am maxed based on feeder and panel source. I calculate my load according to the feed.

BUT, if one just blindly looked at the number of circuits here, I think one would highly recommend a main breaker, to ensure the total is not surpassed, as there are enough circuits to easily do that. But as you can see, the only way I could squeeze in a main breaker is to get rid of my 2U SqD 8 breaker panel (where the blank panel sits in this shot), replace it with the main one, and then somehow redesign this bigger panel to house a huge row of 16 X SqD breakers with the CAMS.



« Last Edit: January 22, 2016, 10:17:31 am by Neil Sakaitis »
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TJ (Tom) Cornish

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #23 on: January 22, 2016, 10:26:07 am »

Loving the feedback, so many people willing to share their best practices and guidelines, great forum !!!

Here are a few shots of my distro, when I first received it. This was the initial panel, which has 8 X 15A circuits with mini breakers. Since I needed more circuits, I have since swapped out the 2U blank panel above it with an 8 X 20A SqD panel. I then split the Edison outlets so I could have a total of 16 circuits. Now keep in mind, I am not using all of them to their full capacity, as I realize that I am maxed based on feeder and panel source. I calculate my load according to the feed.

BUT, if one just blindly looked at the number of circuits here, I think one would highly recommend a main breaker, to ensure the total is not surpassed, as there are enough circuits to easily do that. But as you can see, the only way I could squeeze in a main breaker is to get rid of my 2U SqD 8 breaker panel (where the blank panel sits in this shot), replace it with the main one, and then somehow redesign this bigger panel to house a huge row of 16 X SqD breakers with the CAMS.
Neil, there's a significant problem with the construction of your distro.   The lugs for each cam connector are designed for one wire, but instead, have all of the branch wires jammed in there under one screw.  This isn't acceptable, as the lug wasn't designed to keep tension on multiple small wires.  This will exacerbate the problems due to expansion and contraction from heat.  You will find yourself with loose lugs, high voltage drop, and burnt wires if you keep using your distro this way.

I'm curious - did AmpShop make this for you?  I know they are favored on here due to price, but I've also heard rumors of shoddy construction.  If they made this, that shoe fits.
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Cailen Waddell

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #24 on: January 22, 2016, 10:27:25 am »


Loving the feedback, so many people willing to share their best practices and guidelines, great forum !!!

Here are a few shots of my distro, when I first received it. This was the initial panel, which has 8 X 15A circuits with mini breakers. Since I needed more circuits, I have since swapped out the 2U blank panel above it with an 8 X 20A SqD panel. I then split the Edison outlets so I could have a total of 16 circuits. Now keep in mind, I am not using all of them to their full capacity, as I realize that I am maxed based on feeder and panel source. I calculate my load according to the feed.

BUT, if one just blindly looked at the number of circuits here, I think one would highly recommend a main breaker, to ensure the total is not surpassed, as there are enough circuits to easily do that. But as you can see, the only way I could squeeze in a main breaker is to get rid of my 2U SqD 8 breaker panel (where the blank panel sits in this shot), replace it with the main one, and then somehow redesign this bigger panel to house a huge row of 16 X SqD breakers with the CAMS.

I've never seen wire run from a panel mount cam lock quite like that before.  Someone with more knowledge might jump in here but I would think it would be safer/prudent to use a single piece of large wire to a bus bar then to individual breakers. 

Does the rack have a metal back box on the inside?  I don't see a ground wire coming off to ground the back box...  Surely it isn't just raw wood on the inside.  One loose wire could energize  a rivet or handle...


Sent from my iPhone using Tapatalk
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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 #25 on: January 22, 2016, 10:39:02 am »

Yes the road case is fully lined with a metal liner all around. Honestly, it's been a few years since I ordered this from a company in the US that makes distros, this was a more compact design to be portable. To be honest with you, I was actually impressed with the wiring done under the panel, in terms of connectors and cleanliness, but I hear you on cramming all the wires onto the CAM lugs. Since my roadcase is so small, I cannot imagine how bus bars could be mounted underneath without touching the metal liner of the case. I honestly don't use this panel more than twice a year for a huge home haunt (very high end and technical one). I am now DJ'ing a huge party for my son's school (truss, MACs, QSC, the whole nine) and will need a lot of power, so figured I would bring along my distro to tap into the hall's feed. I have used this panel for close to 8 years now without an issue, no loose lugs, etc...

If I had to do it all over again, I would probably order something new that is more secure and conforms to code better. But I don't plan on tossing this investment in the garbage, so looking for suggestions where I can buy the parts to improve on it.

Keep in mind that to make matters worst, there are 8 more wires on top of the 8 already there tapped onto the CAM lugs, feeding 16 breakers. I definitely like the idea of using bus bars, but would have no idea how to safely mount it within the shallow case.

Worst case, even if it costs some bucks, might send the case to Motion Labs for a rework.

Thanks
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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 #26 on: January 22, 2016, 11:08:29 am »

A couple of thoughts-some really just observations.

You are calling this (I presume because the seller said so), a 100 amp distro.  In reality, there are a maximum of 4 20 amp circuits on a leg-so in reality an 80 amp distro.  Not a safety issue-but perhaps a bit of marketing optimism.

Apparently they are relying on the duplex receptacles being connect to the panel for a ground.  Practically, might be OK-certainly not best practice.  Far better to have a bonding wire to a lug.

From the pics, it appears that there should be plenty of room in the bottom of the box for bus bars, or purpose built terminal blocks.
Something like this would work very nicely:

http://www.cooperindustries.com/content/public/en/bussmann/electrical/products/power_distributionblocksterminalblocks/pdb_series_.html

Just run large wires down to blocks and then #12's back to receptacles-use stranded wire to make it easier to work with and open and close case.
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Steve Swaffer

Neil Sakaitis

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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #27 on: January 22, 2016, 11:27:10 am »

Stephen,

Not following you on the 80A 4 circuit comment. Essentially, according to my theory only, I could have as many circuits as I wanted to, based on the capacity of both the CAM as well as feeder cable. Hence why I expanded my 8 circuit design to a 16 circuit design.

From a pure breaker point of view, I have 8 X 20A plus 8 X 15A, total 280A, well under the 400A rating of the CAMS. Now, if I start to factor in the feeder (SC #2), then that 280A breaker availability falls down to 190A. So if I wanted to do things right, I would probably have to remove some breakers and outlets to ensure the max total does not pass the feeder capacity of 190A, so maybe 6 X 15A and 5 X 20A, and of course balance the load across both legs.

I like the distro block idea in your link, easy for me to incorporate, to install between CAMs and breakers. The model in your link breaks out the leg to 4 smaller connections, but what if I needed 6 or 8 ?? Do they carry blocks with more outputs ??

I guess I would have to rivet these blocks somehow to the inside of the case huh...

Thanks

A couple of thoughts-some really just observations.

You are calling this (I presume because the seller said so), a 100 amp distro.  In reality, there are a maximum of 4 20 amp circuits on a leg-so in reality an 80 amp distro.  Not a safety issue-but perhaps a bit of marketing optimism.

Apparently they are relying on the duplex receptacles being connect to the panel for a ground.  Practically, might be OK-certainly not best practice.  Far better to have a bonding wire to a lug.

From the pics, it appears that there should be plenty of room in the bottom of the box for bus bars, or purpose built terminal blocks.
Something like this would work very nicely:

http://www.cooperindustries.com/content/public/en/bussmann/electrical/products/power_distributionblocksterminalblocks/pdb_series_.html

Just run large wires down to blocks and then #12's back to receptacles-use stranded wire to make it easier to work with and open and close case.
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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 #28 on: January 22, 2016, 11:34:06 am »

Stephen,

Never mind on the question of a bigger bus/distro block design, I clicked on the link for model details and found that they also make a 6 and 12 output design. I guess I would most definitely need the 12 connection model for the neutral, although I would have to drop the number of circuits down from 16, which I probably should do anyways to line up nicely with feeder and main breaker capacity.

http://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/product-literature/bus-ele-pp-3134-pdb


Stephen,

Not following you on the 80A 4 circuit comment. Essentially, according to my theory only, I could have as many circuits as I wanted to, based on the capacity of both the CAM as well as feeder cable. Hence why I expanded my 8 circuit design to a 16 circuit design.

From a pure breaker point of view, I have 8 X 20A plus 8 X 15A, total 280A, well under the 400A rating of the CAMS. Now, if I start to factor in the feeder (SC #2), then that 280A breaker availability falls down to 190A. So if I wanted to do things right, I would probably have to remove some breakers and outlets to ensure the max total does not pass the feeder capacity of 190A, so maybe 6 X 15A and 5 X 20A, and of course balance the load across both legs.

I like the distro block idea in your link, easy for me to incorporate, to install between CAMs and breakers. The model in your link breaks out the leg to 4 smaller connections, but what if I needed 6 or 8 ?? Do they carry blocks with more outputs ??

I guess I would have to rivet these blocks somehow to the inside of the case huh...

Thanks
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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 #29 on: January 22, 2016, 12:32:03 pm »

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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Re: (How) Can I connect my single-phase distro to a three-phase tie in?
« Reply #29 on: January 22, 2016, 12:32:03 pm »


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