is inrush an issue with many HPS fixtures?

[electrofelon]

I am involved with a greenhouse that will be using 356 1000 watt HPS lights. They will be split into two banks that will run at alternate 12 hour cycles, so potentially 178 will come on all at once. I havent received the specs on the ballast yet so I dont even know if they will be magnetic or electronic. I dont have any experience with large contactor controller lighting banks so I was wondering if this could be a potential issue? If so I could use a few time delay relays to split them up if necessary. Are there any standard practices or "rules of thumb" for large banks of HID lighting short of obtaining a unit and directly measuring the inrush? I noticed Siemens has breakers designed for HID lighting. The supply will be 120Y/208. Thanks.

 

[iwire]

HPS?

Maybe MH? Metal halide.

Anyway I know MH draw far more than running current for many seconds while they warm up and we have had to go back to jobs to break the circuits up into smaller loads to over come tripping breakers during start up.

I do not know any rule of thumb.

 

[tom baker]

It depends on the ballast. Some HPS low end ballasts have a high inrush. We use mag reg and they don't have inrush issues.
Need to check the mfg data sheetss.

 

[gadfly56]

HPS?
Maybe MH? Metal halide.

Anyway I know MH draw far more than running current for many seconds while they warm up and we have had to go back to jobs to break the circuits up into smaller loads to over come tripping breakers during start up.

I do not know any rule of thumb.

High Pressure Sodium. Unless you think he's not actually using HPS lamps?

 

[electrofelon]

High Pressure Sodium. Unless you think he's not actually using HPS lamps?

They will be high pressure sodium for sure.

It depends on the ballast. Some HPS low end ballasts have a high inrush. We use mag reg and they don't have inrush issues.
Need to check the mfg data sheets.

Is inrush current information usually provided? I dont think I have ever had to look at ballast specs in close detail before. Ill check once they give me the exact product they will be using. They will be remote ballasts, but that doesnt mean anything. This job is far away - I dont want to have to jump on a plane just to go meter a ballast.

 

[hurk27]

some HPS use a reactor ballast the rest use constant current, but at 1kw I have never seen a reactor ballast used, reactor ballast are in series with the lamp so no inrush, but CC ballast will have some as well as start up current.

Pulse start metal halide uses about half the current when in striking mode, while regular MH or HPS uses double the current in striking mode, I have seen where there was to much VD that many of the fixtures on a run would not fire up and remain in striking mode.

Just a point to ponder, I hope you have a big service even at 178 1kw fixtures you are talking about allot of energy, using a figure of 1kw with a current at 240 volts of about 5.5 amps (with approx ballast current figured in) which is about 1320 watts per fixture, is 234.96kw or about 979 amps@240 v or 565.24 amps if the service is a three phase @ 240v delta or 652.2 amps for a 208/120 WYE

I'm very surprise that they will be using HPS as PSMH are much better for growing light?

 

[iwire]

I'm very surprise that they will be using HPS as PSMH are much better for growing light?

That was why I questioned HPS.

I have not installed HPS in at least ten years.

 

[kwired]

I noticed Siemens has breakers designed for HID lighting. The supply will be 120Y/208. Thanks.

So does everyone else. NEC only requires a HID breaker when the breaker is used as the usual control, so I would assume whatever the difference is has more to do with the contacts being able to withstand the switching more then it has to do with trip characteristics.

 

[mgookin]

I am involved with a greenhouse that will be using 356 1000 watt HPS lights. They will be split into two banks that will run at alternate 12 hour cycles, so potentially 178 will come on all at once. I havent received the specs on the ballast yet so I dont even know if they will be magnetic or electronic. I dont have any experience with large contactor controller lighting banks so I was wondering if this could be a potential issue? If so I could use a few time delay relays to split them up if necessary. Are there any standard practices or "rules of thumb" for large banks of HID lighting short of obtaining a unit and directly measuring the inrush? I noticed Siemens has breakers designed for HID lighting. The supply will be 120Y/208. Thanks.

The luminaire manufacturer should be able to provide you with an inrush waveform for the fixture. Your ambient temperature will affect it as well. Try reaching out to an applications engineer from the company.

I believe lighting circuits are limited to 50 amps. Or is that just outdoor lighting? Is a greenhouse considered inside? A transparent roof is still a roof!

A major (world's largest) retailer we work with uses motor controlled breakers and plc to offset their inrush. Each of their stores is 220-250k s.f. under roof plus all their parking areas, signs, landscape lighting, etc. They even dim indoor lighting based on outdoor ambient light level.

 

[electrofelon]

some HPS use a reactor ballast the rest use constant current, but at 1kw I have never seen a reactor ballast used, reactor ballast are in series with the lamp so no inrush, but CC ballast will have some as well as start up current.

Pulse start metal halide uses about half the current when in striking mode, while regular MH or HPS uses double the current in striking mode, I have seen where there was to much VD that many of the fixtures on a run would not fire up and remain in striking mode.

Just a point to ponder, I hope you have a big service even at 178 1kw fixtures you are talking about allot of energy, using a figure of 1kw with a current at 240 volts of about 5.5 amps (with approx ballast current figured in) which is about 1320 watts per fixture, is 234.96kw or about 979 amps@240 v or 565.24 amps if the service is a three phase @ 240v delta or 652.2 amps for a 208/120 WYE

I'm very surprise that they will be using HPS as PSMH are much better for growing light?

Yes this place will have a big service. Thinking of going with 240 delta if poco allows. I am not a grow light expert, but I dont think you can make a blanket statement about one type being better than another. I think it depends on the crop and what you are looking to do. This proposed site is marijuana and everyone in this industry seems to prefer HPS for the flowering stages. Of course the lights are their choice, Im just hooking them up.

 

[kwired]

Yes this place will have a big service. Thinking of going with 240 delta if poco allows. I am not a grow light expert, but I dont think you can make a blanket statement about one type being better than another. I think it depends on the crop and what you are looking to do. This proposed site is marijuana and everyone in this industry seems to prefer HPS for the flowering stages. Of course the lights are their choice, Im just hooking them up.

I myself would lean toward 480/277 instead of 240 delta. By use of MWBC's you should save on copper, plus the delta would need straight 240 volt rated breakers and not 120/240 breakers which are more expensive. If it is a high leg delta this would only apply to breakers connected to the high leg, but may be more difficult to keep track of getting the right breaker in the right place when doing the installation.

 

[electrofelon]

I myself would lean toward 480/277 instead of 240 delta. By use of MWBC's you should save on copper, plus the delta would need straight 240 volt rated breakers and not 120/240 breakers which are more expensive. If it is a high leg delta this would only apply to breakers connected to the high leg, but may be more difficult to keep track of getting the right breaker in the right place when doing the installation.

Well that is an interesting question and I have pondered that quite a bit. My thinking so far, and I am still open to suggestions on the most efficient way, is this: 277/480 would certainly decrease the service and feeder quite a bit which would be real nice, but as far as the branch circuits, I dont see much gain. First of all 277 isn't that much of an advantage over 240 or even 208 as far as number of lights per circuit. Sure you can use MWBC's with 277 but then I would have to deal with oversized neutral and neutral as CCC due to the non linear loads. With 208 or 240 I could probably not send a neutral along to most of the panelboards which would be a big savings. Then there is hooking up the lights and I would be looking at hardwiring a zillion ballasts, or buying and making up a zillion expensive 277 cord and plug twistlocks. Now 480 ballast would be nice but I still have the hardwiring issue and there are not many choices in 480 remote ballasts. I like the idea of just providing a 6-15 250v recep and they can plug and play with factory cords. I think to some degree the client likes the flexibility of cord and plug. Not suprisingly, everyone in this business is a little nervous about having to move and It think 240V ballasts are more likely to be reusable, resellable, etc. Good point about the 240 rated breakers, thats worth pricing out. Like I said, still in the design stages so Im not set on anything and they still have to get me final lists of equipment. Its a lot of advantages and disadvantages to think about when designing something like this, but I do enjoy it.

 

[kwired]

Well that is an interesting question and I have pondered that quite a bit. My thinking so far, and I am still open to suggestions on the most efficient way, is this: 277/480 would certainly decrease the service and feeder quite a bit which would be real nice, but as far as the branch circuits, I dont see much gain. First of all 277 isn't that much of an advantage over 240 or even 208 as far as number of lights per circuit. Sure you can use MWBC's with 277 but then I would have to deal with oversized neutral and neutral as CCC due to the non linear loads. With 208 or 240 I could probably not send a neutral along to most of the panelboards which would be a big savings. Then there is hooking up the lights and I would be looking at hardwiring a zillion ballasts, or buying and making up a zillion expensive 277 cord and plug twistlocks. Now 480 ballast would be nice but I still have the hardwiring issue and there are not many choices in 480 remote ballasts. I like the idea of just providing a 6-15 250v recep and they can plug and play with factory cords. I think to some degree the client likes the flexibility of cord and plug. Not suprisingly, everyone in this business is a little nervous about having to move and It think 240V ballasts are more likely to be reusable, resellable, etc. Good point about the 240 rated breakers, thats worth pricing out. Like I said, still in the design stages so Im not set on anything and they still have to get me final lists of equipment. Its a lot of advantages and disadvantages to think about when designing something like this, but I do enjoy it.

If they are electronic ballast you will have harmonics to consider if they are magnetic ballast they should be a linear load. I won't say electronic ballasts don't exist for HID but I can't ever recall seeing one either, and I think magnetic ballasts are still somewhat king of HID's. So neutral size is probably not too much concern, even if it is you will still use less copper with the 480/277 system then with the 240 delta.

True luminaire voltage and current are going to be fairly similar, but amount of copper needed for the MWBC's will be less then for the 240 volt delta. Every three circuits @480/277 uses 4 conductors. Every three circuits @ 240 uses 6 conductors, and at a little higher amps and as a result possibly larger conductors as well. Voltage drop becomes a issue more quickly at the lower voltage so there may be increased copper use for that reason as well.

Cords? I would try to order luminaires with cords already installed - they generally can do it cheaper at a factory then you can in the field.

Reuse or reselling? Get ballasts with multi voltage taps, then they are usable from 120 to 277 or maybe even 480 in some instances.

I did have a guy purchase some used HID's one time only to find out they were 277 volt only (he was putting them in a building supplied by 120/240 single phase). Since he opted for cheap on the luminaires, I opted for cheap and found a buck boost transformer on E-Bay and we made them work.

 

[electrofelon]

If they are electronic ballast you will have harmonics to consider if they are magnetic ballast they should be a linear load. I won't say electronic ballasts don't exist for HID but I can't ever recall seeing one either, and I think magnetic ballasts are still somewhat king of HID's. So neutral size is probably not too much concern, even if it is you will still use less copper with the 480/277 system then with the 240 delta.

True luminaire voltage and current are going to be fairly similar, but amount of copper needed for the MWBC's will be less then for the 240 volt delta. Every three circuits @480/277 uses 4 conductors. Every three circuits @ 240 uses 6 conductors, and at a little higher amps and as a result possibly larger conductors as well. Voltage drop becomes a issue more quickly at the lower voltage so there may be increased copper use for that reason as well.

Cords? I would try to order luminaires with cords already installed - they generally can do it cheaper at a factory then you can in the field.

Reuse or reselling? Get ballasts with multi voltage taps, then they are usable from 120 to 277 or maybe even 480 in some instances.

I did have a guy purchase some used HID's one time only to find out they were 277 volt only (he was putting them in a building supplied by 120/240 single phase). Since he opted for cheap on the luminaires, I opted for cheap and found a buck boost transformer on E-Bay and we made them work.

Definitely some good points. The 480 gear would be more expensive, but maybe not so much with factory ordered equipment and could be offset and then some with wire and raceway savings. Definitely worth another look.

 

[jrannis]

I am involved with a greenhouse that will be using 356 1000 watt HPS lights. They will be split into two banks that will run at alternate 12 hour cycles, so potentially 178 will come on all at once. I havent received the specs on the ballast yet so I dont even know if they will be magnetic or electronic. I dont have any experience with large contactor controller lighting banks so I was wondering if this could be a potential issue? If so I could use a few time delay relays to split them up if necessary. Are there any standard practices or "rules of thumb" for large banks of HID lighting short of obtaining a unit and directly measuring the inrush? I noticed Siemens has breakers designed for HID lighting. The supply will be 120Y/208. Thanks.

You are going to end up with several circuits, you may as well take advantage of that and control them with contractors and some TD relays.

 

[kwired]

Definitely some good points. The 480 gear would be more expensive, but maybe not so much with factory ordered equipment and could be offset and then some with wire and raceway savings. Definitely worth another look.

You will also have either less controls because you can get more on one circuit or will have smaller amp rated controls to save on costs.

I am usually wanting to go with 480 volts for motor applications, but this is not really much different other then you likely have a neutral conductor with the circuit(s).

Sure 480 volt gear is sort of higher priced, but you are not exactly comparing apples to apples in most cases. How much does a 200 amp 480 volt panel cost compared to a 240 volt panel that has to be 400 amps in order to be able to serve the same total load? Many will give you better pricing if you order a panel, breakers, and other needed gear from same manufacturer as compared to ordering single items.

 

[electrofelon]

You are going to end up with several circuits, you may as well take advantage of that and control them with contractors and some TD relays.

Right. If the supply is 208 or 240, I can buy premade lighting contactors that have receps mounted on them and do 8 lights for $225. Space them evenly throughout the room and feed them with #6 or maybe #4 Al mc. That would be real quick. I would need 52 of them. I am going through the numbers of making up my own - more labor but quite a bit less material cost and it would have to be this way if 277/480. Since the rooms alternate in 12/12 cycles, I thought about using double throw relays. I could incorporate some TD relays so maybe 1/4 of the light come on at once.

Sure 480 volt gear is sort of higher priced, but you are not exactly comparing apples to apples in most cases. How much does a 200 amp 480 volt panel cost compared to a 240 volt panel that has to be 400 amps in order to be able to serve the same total load

And that could be a big consideration for the service. With 208 I am looking at 1200 amps, maybe 1600 depending on final details so I am into the switchboard category. 600 amp at 480 would do it.

 

[jrannis]

Right. If the supply is 208 or 240, I can buy premade lighting contactors that have receps mounted on them and do 8 lights for $225. Space them evenly throughout the room and feed them with #6 or maybe #4 Al mc. That would be real quick. I would need 52 of them. I am going through the numbers of making up my own - more labor but quite a bit less material cost and it would have to be this way if 277/480. Since the rooms alternate in 12/12 cycles, I thought about using double throw relays. I could incorporate some TD relays so maybe 1/4 of the light come on at once.



And that could be a big consideration for the service. With 208 I am looking at 1200 amps, maybe 1600 depending on final details so I am into the switchboard category. 600 amp at 480 would do it.

I was just assuming that it was one large area and that you could just ramp up the lighting by using time delay relays controlling a few contractors.
I think I understand that you have some zones or separate areas.
The 1000 watts is what's creating the challenge. Could you use LED or high bay T5s for this application?

 

[GoldDigger]

...Could you use LED or high bay T5s for this application?

The conventional wisdom is that HPS is the ideally balanced spectrum for particular types of plant growth, and that no amount of higher illumination with a different spectral mix would do as well.
I have not seen Ag Extension papers on the subject though.

 

[jrannis]

The conventional wisdom is that HPS is the ideally balanced spectrum for particular types of plant growth, and that no amount of higher illumination with a different spectral mix would do as well.
I have not seen Ag Extension papers on the subject though.

I saw in a grow forum that they would use the same fixtures for MH and HPS and install a switch to bypass the igniter when using the MH lamps.
Point being that they used two different color lights.
Maybe the OP is using half of the lights 12 per day, full lights the other 12. Maybe the guys on the grow forum were using MH as the daytime mode:huh: