Client wants a service redesigned due to gear availability

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92VR4

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Location
Southeast US
Occupation
Electrical Contractor
I've had a potential client approach me with a somewhat unusual request. They have a project that requires a new service. Their original contractor pulled permits, took the deposit, and disappeared. Now they are several months behind, and don't want to/can't wait on the 6-month+ lead time for the spec'd panels. They've asked me to come up with an alternative using readily/quickly available equipment. This is a rural jurisdiction that will accept a one-line, panel schedule, load calcs, etc from a licensed EC, so I don't have to involve an EE unless things get complicated, although I may just for CYA reasons.

The original service was designed to be 600A single-phase with a 600A fusible disconnect feeding two MLO 600A 3R panel boards in series, with the first being feed-thru. (20) 50A circuits feeding power pedestals, (2) 125A circuits and (1) 200A circuit for sub panels, and a handful of 20A convenience receptacle circuits. Obviously the best solution is to wait on the spec'd equipment, and I'm going to push that, but it may not be an option.

My first thought was this:
600A fusible disconnect with parallel 300 MCM Cu fed through a trough. (6) sets of taps with 5-port Polaris connectors, feeding (2) 125A fusible disconnects, (1) 200A fusible disconnect, and (3) 200A main-breaker 3R panel boards. All this is outdoors and built on a rack. Obviously with an appropriately sized trough and tap conductors.

It works on paper, but is it compliant? The feeders don't terminate anywhere except the last set of Polaris connectors, is this a problem? I'm familiar with tap rules, but we're mainly residential and light commercial so we aren't using them often.

Its going to be large, kinda ugly, and probably cost just as much or more than doing it the "right" way by the time it's all said and done. I don't like using all those Polaris connectors like that, but I'm not finding gutter taps that are made for a parallel feed.
 
92VR4 said:
My first thought was this:
600A fusible disconnect with parallel 300 MCM Cu fed through a trough. (6) sets of taps with 5-port Polaris connectors, feeding (2) 125A fusible disconnects, (1) 200A fusible disconnect, and (3) 200A main-breaker 3R panel boards. All this is outdoors and built on a rack. Obviously with an appropriately sized trough and tap conductors.
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It seems like a good design but I would probably opt for a full 600 amps worth of conductors on the load size of the 600 amp disco. What the calculated load? Sounds like a lot of equipment for a 600 amp service.

Welcome to the Forum. :)
 
infinity said:
It seems like a good design but I would probably opt for a full 600 amps worth of conductors on the load size of the 600 amp disco. What the calculated load? Sounds like a lot of equipment for a 600 amp service.

Welcome to the Forum. :)
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It sounds like it to me too, but its calculated at 450A. They are power pedestals for RV sites and it appears the pedestal manufacturer provided the load calcs and service design. I've got to go back over everything and verify it, I already see some issues with voltage drop and conductor sizing (one-line they gave me was using parallel 4/0 Al to feed the panels). I didn't want to invest a lot of time into it until I had a basic plan to present and could get a contract signed, because redesigning/correcting all this is definitely getting billed.

I agree with using the 350MCM also.

Thanks for the welcome. I've used the Forum for a long time as a source of information, looking forward to becoming more involved.
 
What can you get in reasonable time might be the first question?

One manufacturer might not be possible to get what you want, another one might be possible.

Factory assembled meant lead times even when there wasn't supply chain problems. If there are stock items available to build the panel needed that might be the way to go. Most Square D panels I have ordered in the past have come from stock items and needed to be field assembled, was always the quickest way to get what I needed.
 
kwired said:
What can you get in reasonable time might be the first question?

One manufacturer might not be possible to get what you want, another one might be possible.

Factory assembled meant lead times even when there wasn't supply chain problems. If there are stock items available to build the panel needed that might be the way to go. Most Square D panels I have ordered in the past have come from stock items and needed to be field assembled, was always the quickest way to get what I needed.
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I have to see, but we ordered an 800A single-phase 3R panel about a month ago and the ballpark lead times I was given from a couple suppliers were: Square D- 4 Months, Siemens- 6 Months, Eaton- 8-10 Months. And of course, those aren't guaranteed. I've never field-assembled a panel beyond throwing the guts in the tub, but I certainly wouldn't have a problem with it. I'll have to ask about that.

The original plan ( 2 600A panels) is still my preference, and maybe we can get some 400A panels quicker. I just wanted to get my ducks in a row so I can go to them and say, "Let's see what we can get and try and make plan A work. If the timeline doesn't work then here is plan B (400A panels), and if that won't work then here is plan C (what I described above)"
 
92VR4 said:
It sounds like it to me too, but its calculated at 450A. They are power pedestals for RV sites and it appears the pedestal manufacturer provided the load calcs and service design. I've got to go back over everything and verify it, I already see some issues with voltage drop and conductor sizing (one-line they gave me was using parallel 4/0 Al to feed the panels). I didn't want to invest a lot of time into it until I had a basic plan to present and could get a contract signed, because redesigning/correcting all this is definitely getting billed.

I agree with using the 350MCM also.

Thanks for the welcome. I've used the Forum for a long time as a source of information, looking forward to becoming more involved.
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Does that design meet or exceed the requirements of 551.73?
 
don_resqcapt19 said:
Does that design meet or exceed the requirements of 551.73?
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This would be my concern also. It's going to be tricky as the demand factor for multiple pedestals on a 600 amp (feeder) is going to be different from the demand factors on separate 200 amp panels.
 
don_resqcapt19 said:
Does that design meet or exceed the requirements of 551.73?
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Looking closer, yes and no. It meets the requirements for only the pedestals. They haven't factored in any of the other loads at the facility, and I don't have schedules for any of the sub-panels, so those loads going to have to be figured out. I'd say I don't know how that design was approved, but I'm not surprised in this neck of the woods.

augie47 said:
This would be my concern also. It's going to be tricky as the demand factor for multiple pedestals on a 600 amp (feeder) is going to be different from the demand factors on separate 200 amp panels.
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I didn't even think about it changing the demand factors with the smaller separate panels, I was just looking at the service as a whole. 3 200A panels with 7/7/6 pedestals isn't going to work, that's 192.6A on the 7-pedestal panels and I could easily see the big tricked-out RVs drawing a fairly steady 30-35A on a hot day, which we have plenty of here.

It looks like 4 225A panels with 5 pedestals each would do the trick with some wiggle room for the convenience receptacle circuits. Calculated load there is 162.5A per panel.
 
I’m having kind of opposite problem, our locality require engineered blueprints for commercial and industrial, but not residential. I already know what I need to build, and will probably have most of it built before I get the engineered blueprints! Been waiting since last November for the prints. New building and new 1600 amp service. The new equipment arrives in March, so I need to have the service hot before then, but can’t order the gear before the engineer draws it up. I may have to do the same thing you’re doing due to supply restraints.
 
92VR4 said:
Looking closer, yes and no. It meets the requirements for only the pedestals. They haven't factored in any of the other loads at the facility, and I don't have schedules for any of the sub-panels, so those loads going to have to be figured out. I'd say I don't know how that design was approved, but I'm not surprised in this neck of the woods.



I didn't even think about it changing the demand factors with the smaller separate panels, I was just looking at the service as a whole. 3 200A panels with 7/7/6 pedestals isn't going to work, that's 192.6A on the 7-pedestal panels and I could easily see the big tricked-out RVs drawing a fairly steady 30-35A on a hot day, which we have plenty of here.

It looks like 4 225A panels with 5 pedestals each would do the trick with some wiggle room for the convenience receptacle circuits. Calculated load there is 162.5A per panel.
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Why not 4 200-amp panels? Are 225 easier to get?
 
92VR4 said:
I have to see, but we ordered an 800A single-phase 3R panel about a month ago and the ballpark lead times I was given from a couple suppliers were: Square D- 4 Months, Siemens- 6 Months, Eaton- 8-10 Months. And of course, those aren't guaranteed. I've never field-assembled a panel beyond throwing the guts in the tub, but I certainly wouldn't have a problem with it. I'll have to ask about that.

The original plan ( 2 600A panels) is still my preference, and maybe we can get some 400A panels quicker. I just wanted to get my ducks in a row so I can go to them and say, "Let's see what we can get and try and make plan A work. If the timeline doesn't work then here is plan B (400A panels), and if that won't work then here is plan C (what I described above)"
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Which series panels (Square D anyway) were you looking at? From recollection I don't think you can get NQ or NF series with over a 600 amp bus. Over that would about need to go with their I-line panels. I-Line doesn't come in a single phase version, you can still use on single phase though, just don't use one the buses and only order breakers that connect either or both of the two buses you are using.
 
kwired said:
Which series panels (Square D anyway) were you looking at? From recollection I don't think you can get NQ or NF series with over a 600 amp bus. Over that would about need to go with their I-line panels. I-Line doesn't come in a single phase version, you can still use on single phase though, just don't use one the buses and only order breakers that connect either or both of the two buses you are using.
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They may custom make a 600 amp single phase iLine, my old boss put one in his new house about 6 years ago. I imagine it was pretty penny!
 
Is this a $$$ project? Trystar has UL to make custom switchboards they could probably make you something but I would expect it to cost some $.
 
You could always look at used panel boards, probably something on eBay that would work that's in decent shape. It seems like if they can't wait your choices are going to be used equipment or use 200 amp load centers. If you go the load center route, might want to look at something like a bussed gutter, would probably be more convenient and cheaper to make all those taps to the load centers.
 
hillbilly1 said:
They may custom make a 600 amp single phase iLine, my old boss put one in his new house about 6 years ago. I imagine it was pretty penny!
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I'm sure they can. Not sure it would really cost much less than a stock item unless maybe you had a lot of other items on the order with it.

And that is before the supply chain issues of the past couple years.
 
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