Power for laser room

(mostly copying a PM I had with @Jon )

Pearl and Tarkin are now in the classroom awaiting power, while Blue and Red are not moved but probably will move later. There is a hole ripped in the wall to the bay door alcove where the blowers and outlet vent bezel (“knee wall”) will sit, we’re not doing roof penetrations at this point. Air compressors can go here, but chillers probably cannot.

It is possible to put the chillers on the other side of the wall in “coworking”, but this will be noisy.

There is not currently any doorway left to keep dust out of the (laser) classroom or lounge.

There is ample panel amps capacity in the lounge panel. It is full of breakers but many are unused. There are a couple of unused 100A 3ph breakers. Those are oversized, so one can be replaced with a 30A 3ph breaker for Tarkin (I have one, it is sitting on top of Tarkin). Pearl can use a 20A 3ph (I don’t have), or a single phase but it might need to be 30A. I think we need to be forward-thinking and just make it all 10AWG 3 phase.


The one exception in that Blue (not in the laser room yet) is 120VAC (20a circuit is fine), so it requires a neutral. It might be capable of 208V operation I’d have to check.

In the past we ran power for the blowers through power-bearing wiring through switches near the lasers then off to the blowers in the alcove. That’s not essential, and a significant PITA for a number of reasons. Pearl and Tarkin’s controllers have relay outputs for turning on the blower while running jobs. The relay could switch the power to the blower at the machine and run flex for the blower’s power from there to the alcove, but it may make more sense to run power to the alcove and only low-voltage relay control lines from the machines to switch power with relays inside the alcove.

Looking at the numbers, I’d say another 3ph 30A circuit would be needed, running from the panel to the alcove. However, for this one, a neutral is needed. Armorlite MC flex comes in 10/3 + ground but it needs to be 10/4+g. The neutral will probably have green insulation inside the flex. Is it legit to retask the 10/3’s ground as the neutral and then get ground from another wire not inside the flex? Ground wires aren’t current-bearing and in some scenarios just go to a cold water pipe. I was thinking more of it being wire nutted to a ground from the nearest outlet.

Electrically, this should be fine, it’s a matter of whether code allows it. This does mean we have more than 3 current-bearing conductors in the flex. It might be required to still be in a metal-clad envelope, which might still be easier to run as flex from the nearest box instead of trying to get a whole 10/4+g run which might have to be rigid conduit.

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Just asking a question about the 3 phase plus neutral. It is kind of a European standard. Do we actually need it?

@Jon pointed out the compressors will be replaced by shop air. That’s not there currently. If we move the compressor we use for Red, that is a 120VAC device so a neutral would be needed. Red and Blue’s current blowers are 120VAC. The blowers I have to use on Pearl and Tarkin would run off 208v. There’s one other blower I have that is pretty large, but I’m not certain what its voltage is.

I’m just trying to not rule out 120V stuff there entirely. Perhaps it would make more sense to route 10/3+g there, and then a separate 120V hot/neutral/ground if needed.

Electrically, this should be fine, it’s a matter of whether code allows it.

Logically it works, but I’m pretty sure code won’t allow that. Code generally doesn’t like the paths of wires diverging. It allows one wire to get cut, while not cutting the whole bundle. Half of the point of code is to prevent stupid mistakes from being possible. If there’s a 100a 3p breaker, it’s possibly feeding a subpanel, is the breaker currently on or off?

If you can give me photos of where you want the drops, and what types you need at each location, I can contact a licensed electrician (family) to find out exactly what needs to be done & how to do it cost effectively. It can possibly be run in metal flex (not BX, but similar to it, but less of a pain to deal with pipe bending) and rigid isn’t that hard to work with. At these sizes, you probably won’t find MC or BX that’s large enough. They expect the electrician to run the conduit.

The ground might be allowable to run that way, code has different rules.

MC flex in 10/3+g is readily available for 30A 208v 3ph service with a ground but not a neutral. We do need “something” up ASAP, but we’re not completely sure of the ultimate layout. We might run flex outside the drywall for now so it can be moved later. This might mean if it’s near the panel, leaving some extra slack length above the drop ceiling so it can be further from the panel later without adding a junction box.

Pretty sure code’s always going to assume worst-case scenario for bonding (grounding) wire size - i.e. a load just small enough to not trip the breaker quickly. They’ll want the ground wire large enough to be effective (i.e. no significant potential to other grounded objects) and to not heat up, meaning the same size as the phase wires. If you attempt to share that wire, they’ll want it appropriately sized for worst-case on all affected circuits.

Water pipes were allowed in the past, as were ground wires of a smaller gauge. The former definitely isn’t allowed now, and I don’t think the latter is either.

If the third thing for Tarkin was the blower, that’s not going to be in the same location as the rest of the stuff anymore. We should run two 220V circuits, one each for the laser and the chiller. Do they both need to be 30A, or just the laser?

For the exhaust closet, we should be able to get by with one 220V 20A circuit with neutral - two 220V outlets (one for each big blower) plus one 120V outlet on each leg would satisfy code requirements for balanced phases.

The blower that’s sitting in the (new) laser room right now I assumed was the one for Tarkin, and it’s labeled 110V 550W (5A). Too big to legally hard-wire four on a 20A circuit, but with plugs and outlets technically OK. I’ll check for nameplates on the other exhaust blowers next time I’m in.

edit: Looking back at the Tarkin spreadsheet, I think the three phases of Tarkin are two laser power supplies and the chiller. So it probably still makes sense to run a 3-phase circuit and wire it to three 220V outlets.

The laser and chiller should be on one 30A 30ph. Separating them only complicates the wiring issues.

The blower can be on another circuit. I thought the black blower was 220v but if you saw 120v on it I’ll believe that.

Both of the blowers we’re using now are ~1hp each IIRC, so over 6 amps 120V each.

If the current blowers for Red and Blue are 1hp, the Tarkin blower seems a little underpowered. At least it’ll be the shortest run

@dannym I spoke with @EricP and I think it was @Jon earlier tonight. We discussed the wiring for the area.

What it tarken’s actual power input? 3x 220 30A connections, or one 3 phase 30A connection? Don’t worry about what you think is easiest to run wires for… What does it actually require on the spec sheet? I don’t have the spec sheet so idk.

We are also planning on running 2x 20A 220V for Pearl and it’s cooler, and a spare 20A 220v if possible between the two for future expansion.

Finally 2x 120v connections to the exhaust closet next to the coworking space.

Pulling grounds from other locations… NEC 300.3(B) says (except in a few really strange edge cases) all conductors of a circuit, including grounds and bonding, must be in the same raceway/cable/cord/etc. So unless someone can say which of the strange exceptions we fall under, I don’t it’s allowed.

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I haven’t seen the laser power supplies yet, but the chiller is a standalone appliance with a 220V single-phase plug on it.

Tarkin has two 11A @ 208V loads, another of about 2A @ 208v guesstimate, and the chiller’s nameplate is “2-9amps”. As it has a R410A compressor it will draw a surge at startup. Earlier I was counting the blower too but not now. If put across just two phases, that’s 33A @ 208V which is pretty high.

Converting unbalanced 3 phase 208v delta loads to wye is complicated, but it’s luckily it’s quite close to a balanced 11A peak when they’re all running. That is 19A as wye across 3 phases which is how breakers and wiring see it. That’s too much loading for a 20A circuit thus the 30A 3ph.

Pearl is two 208V loads, should be a bit over 10A @ 208v for Pearl and maybe 4 or 5 constant for its chiller, which also draws a lot of amps on starting. It might work with one 20A 208v circuit, although there is benefit to distributing the loads on the phases. Once you decide to use two phases of 208V for the pair instead of one large one, that’s using all 3 wires so it’s literally a 3 phase outlet at that point whether the third 208v is used or not.

That’s the math and rationale for one 30A 3ph and one 20A (or 30A) 3ph. The only real liability is taking up three breaker slots on each instead of two. The panel seems to have ample room at this time. There’s 8 slots labeled “dead” (unwired), one unlabeled single is off. There’s a dual that is on but unlabeled, and another single labeled “?”. So, even with adding more circuits for 3D printers and exhausts, we have an excess.

Also, the lighting may have been split into more breakers than it needs right now, because we’ve mostly switched from fluorescent to LEDs.

But they ARE separate loads, physically. The chiller will have its own 208v single phase plug that will probably need to go through the laser to make sure it’s sharing on the intended phase pair, rather than combining with one of the phases already carrying a >11A load. I think that’s best instead of trying to use multiple wall outlets, although that is an option. But, how that terminates as a plug is a lesser issue IMHO, just getting power where it needs to go is the first priority.

I do have a blower we might want to use that is a 208V. It’s only maybe 3-4amps but it’s a 208v load BTW.

Okay, we spent some time researching the actual machines, along with @EricP Here’s the updates/new plans.

The power for tarken (just the servos) is marked as 110v. We’ll plug tarken into the wall directly behind it for that. The power supply for the laser is marked 220V, 20A. The Chiller is marked as 220 as well (something below 20A). Given that it produces heat, we were thinking of putting the chiller in the closet. If we need access to the chiller, we can open the bay door from outside to get really good access to the closet & chillers.

The power for Pearl is 208v 20A for the machine, and 208v 20A for the chiller. Since it doesn’t have remote starting, we’ll put a plug in the middle of the wall for now, so you can manually start pearl’s cooler. We’ll install a 208 plug in the closet for it as well, so we can power it in the closet once we get the ability to remote start that chiller.

Because of all the blowers in the closet, we’ll have a dedicated 110v run for powering the blowers.

We’ve checked, and there’s plenty of space in the panel box for the breakers in the above configuration. Once we move Pearl’s chiller into the closet, we’ll have a free 20A plug in the laser room if we want to move red or blue in there at a future point (or another machine). We can do most of this with the existing materials we have around the space. I’ll provide a list of the items we don’t have to @EricP so he can order them from amazon/homedepot/whatever.

@dannym Since you’ve worked with tarkin the most, any reason you see why this plan won’t work? It’s pretty simple to execute with the supplies we have on hand. Even with the spike from the chillers starting, 20A should meet our needs. I only see one power supply for Tarkin’s Lasers?

@Jon Can we run the chillers in the closet, or do we want to run them in the laser room instead? Eric said he wanted your thoughts on this. Also are you happy with the over all plan? Once I have your approval, I’ll start pulling wires within a few days.

Please use the figures I am providing.

Tarkin’s motor drive supply can run off 120V, I’ve been using the supply that way to set it up, but it is unnecessarily complicated to run a separate circuit for it when it can run just fine off the same 208V the laser’s power supply uses. That’s the one I estimated at 2A @208v.

The power supplies for Tarkin’s laser are two 11A @ 208V, I have them here. The supplies’ nameplates are 20A in, but the loads are fixed and cannot exceed 11A per supply. The chiller’s nameplate is “AC 208v-230V, 2A-9A”. For 208V, expect the higher part of the range.
Pearl’s actual draw is also fixed by its laser source to a bit over 10A @ 208V. Pearl’s chiller actual draw I have not measured. Based on its cooling capacity, I am estimating 4amps-5amps running.

Chillers do pump out heat, that’s the point. They do need good ventilation and cannot recirculate air in a closed area. The “closet” (I call it “alcove”) is not entirely closed off, but it is intended to get hot and intended to insulate off that area and minimize airflow. The metal door is uninsulated, the drywall has fiberglass to insulate the room from the heat in the alcove, and the builders tried to limit how much air can be exchanged through the ceiling. It is acceptable to put blowers there, but not chillers. They will rapidly overheat the any enclosed or semi-enclosed area and result in equipment failure.

Tarkin’s chiller does have a big round exhaust vent on top- it is possible to use a duct to vent the warm exhaust air above the drop ceiling to keep the room cooler. That’s a workable config because the chiller is taking in cool room air.

The chillers can be placed on the coworking side with no physical issue, except it’s moving the fan noise over to that area. Just not the alcove-closet area.

With two 11A @208V loads and say 2A @ 208v, if we wire over only two of the building’s phases, that would require 30A wiring at least. More to the point, that’s a 100A service and, for the sake of the facility, this manages our capacity significantly better if that load is split across phases. That’s my preference, anyways. It was more necessary when I was budgeting with the chiller on the same run.

Building phases- the “hots”- are typically labeled W, X, and Y. So wiring from W to X- two hots- is 208v, but both phases are loaded with ~24A which isn’t good management if you don’t have to do to this. Instead we should just include a third wire and Tarkin can distribute the load so W-X has one supply and X-Y has the other. The 2A for the motor drive is not a big deal but I have it down for spanning Y-W.

If the chiller does not go on the Y-W leg at the machine’s outlet, that’s ok, but Tarkin should still have 3 phase. In that case, maybe a 20A 3phase would suffice, but I don’t see why we don’t play it safe and run as a 30A. 10/3+g flex is readily available, and I put a 30A 3ph breaker sitting on top of Tarkin for this, plus outlet and plug, so let’s just do that.

Pearl and its chiller can “probably” run on a single 20A 208v circuit (two hot phases, one circuit we typically still call “single phase”).

If the chillers are grouped together with different power, that’s a valid thing to do too. In that case Pearl needs only the its single phase 208v, but Tarkin’s power is still best managed by using 3 phase to distribute the load across phases, even if it’s not well balanced.

In all this, be mindful of which phases are being utilized with large loads like this. If we split up Tarkin and the chiller on two different wiring runs, then Tarkin would load W-X and Y-Z. In that case we should have the 208v for its chiller utilize Z-W phases.

We do have the single-phase 208v outlets that Pearl used still installed on wiring where it used to sit. One is 20A, the other 30A IIRC. Those can be reused, but outlets are cheap and work where they are, so I’d say leave them there, applications will come up needing them.

For now, let’s keep this simple and keep the chillers in the same room. It’s noisy, I don’t like that, but we can work on that later, right now I want to get this stuff running and available as soon as possible. 30A 10/3 is cheap, and we have 30A hardware, so I’d say run the 30A 3 ph over there. Pearl can run off a single 20A for sure if the chiller is not on the same circuit, and 20A would probably be enough capacity for both Pearl and its chiller too. You outline two 20A 208V circuits, which is fine too, better in some ways.

But, it is basically valid to put Tarkin on single-phase 208V without the blower or chiller on that circuit, in which case it will need a 30A circuit and it’s going to actually use most of that.

I’ll be by later to survey the situation, but I saw the pictures of placement yesterday, they’re fine.

Sorry, man- I just looked at this after posting… big wall-o-text, wasn’t it? Well I was working through these scenarios of moving chillers to different runs in my head.

I’m aware of the load balancing concerns, put all of that aside for now. I’ve had an electrician review this, so I understand the situation better, and I’m aware of what’s easy/hard to run. I’m also taking into account what supplies we already have on hand.

For Tarkin, I was shown a 220V, 20A power supply, that outputs 48V, 50’ish amps. Is that the right power supply for Tarkin? Does it have multiple of those power supplies? Somewhere we’re not synced up on the input for Tarkin.

For the Chillers, we were thinking that the ones in the “closet” would be vented outside, because you’re correct, they’d generate a bunch of heat. Venting them outside is the best way to get rid of the heat from the building.

For Tarkin’s motors, we can plug it into the wall right behind Tarkin. There’s already a plug there. 4A @ 110v isn’t much load for that circut.

Also: I’m aware of how 3 phase works. I’m trying to ensure any new wiring is up to code, and is properly wired. There’s stuff that we’ve already identified that’s not to code.

Edit #2: Perl’s outlets are the ones that are miswired.

I’m not sure what you were looking at, but Tarkin is two 11A @ 208V supplies. They can be arranged spanning different phases, or loading up one phase.

Putting the power supply for Tarkin’s motors on a separate 120V circuit would function, but there is no benefit to doing so, they can run off the 208V and are not enough current to put anything over a limit in any config I worked out. I was using 208V in setting it up but that was just because it was convenient at the time. In the end picture it just seems to be an extra, unnecessary cord.

Venting the chillers outside was a situation I considered first. It came down to considerable problems, and was not actually helping- they do push out heat, but chillers are high CFM, and every cubic foot blown out must be brought in elsewhere as fresh air, which will often be hot and have a high moisture load. We do not have provisions for this much make-up air, and for the difficulties, it’s not going to gain anything I can see, as the make-up air is as much or more of a cooling load than the chillers’ exhaust. Due to the large intake areas, I could see no practical way to avoid recirculation, and/or taking in some of the laser’s exhaust since the blowers are there too. And these chillers aren’t designed for outdoor use, they may be unable to run when taking in hot outside air on the hottest of days, and it could cut the life of the equipment drastically shorter.

I would say, as much as I like to do elaborate plans, let’s just do the normal, simple thing here- keep the chillers inside. For now, at least.

I’ve had a neat idea I talked with @Jon about- converting a mini-split into a central chiller by turning the inside unit- the evaporator- into a liquid heat exchanger. That one WOULD be placed entirely outside. It’s got a lot of sound logic and maybe a good end goal, but not something to deal with today.

Sorry if I was pedantic on 3-ph, I see you’re versed. What was wrong with Pearl’s outlet BTW? I didn’t wire that one. That started as a 3 phase + neutral run ending in an L21-20, then got split into 3x 208v outlets in a delta to supply Red, Pearl, and Pearl’s chiller. They were supposed to all be L6 20A NEMA, but someone found a 30A on hand and put that in there, even though it shouldn’t be.

Okay, so I was shown the wrong power supply. That’s where my confusion came from. Okay. We’ll plan 5 drops on that wall. 3 for Tarkin (2 for the laser and 1 the cooler), 2 for pearl (1 for each). If we have enough wire left over, I’ll run a spare. We have the slots, I just don’t know if we have enough wire for it. 1 Drop in the closet for the blowers.

The 120V is just for simplicity. If you want to wire it to one of the 220’s or plug it into the wall, that’s fine, but we shouldn’t beef anything up just for that line. So I’m going to ignore it. Worst case it gets plugged into the wall.

Re the chillers: Okay, if you’ve crunched the math on it, they’ll go in next to the machines.

From a practical point of view, running 220 circuits is much easier then running 3 phase. We already have a roll of 12/3 AC, it’s easier to bend, and just overall takes less effort to run. 10/2 and 10/3 start getting expensive, annoying to run, and we don’t have any on hand. Places charge a huge premium for anything related to 3 phase because it’s really only used by large businesses.

One of the plugs for Pearl is a 110 plug, not a 220 plug. And if there was a cable that was splitting a 3 phase into 3x 220’s, that’s possibly unsafe. It starts getting complex when you start looking at all the possible failure modes.

I understand 3 phase well enough to know it needs to be treated with respect, caution and understanding. It has a lot of edge cases, not just basic balancing like you were talking about. And when you’re adding large appliances (like huge lasers or air conditioners) to it is when you need a professional.

Regarding chillers in the closet - I think what they’re saying is the closet would intake ambient outside air and exhaust heated outside air back outside. It didn’t occur to me when we were talking about split-chillers, but it’s even simpler to just put the whole chiller outside (thermodynamically, at least) and just route the chilled water to the laser. The only question would be ensuring sufficient outside air circulation in the closet/alcove.

Danny has a point though. If we cycle outdoor air through the chillers, if they aren’t rated for cycling outdoor air through them, they’ll get clogged up.

yeah let’s get them working now in the laser room, and think about optimization after the kinks are worked out.

I wouldn’t object to just putting them in coworking (it’s always cold in there) but the people who sit there day-to-day might have other ideas :slight_smile: