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New Spot! Can Someone Check My Electrical/RO Water Math Please?

Entire house garage will consist of a Veg Room, Flower Room, and separate Drying room! Planning on running 2 mini-split AC units and a portable unit. one for each room unless otherwise suggested.

Planning to run four Gavita 1000 Watts DE in the flower room.. or maybe even just 600 watts.. for four big plants in PPK.. 600 watts HID @ 240 volts = 2.5 amp
They are 240-volt gavitas that means each light will need 4.16 amps. (1000 divided by 240)... So I'd want all four gavitas on a 20-amp breaker right? not a 25- amp?


and if the mini splits get their own 20 amp breakers @ 240 volts does that mean does that mean they use 40 amps total or 20 amps? Trying to figure out if I need a 100-amp subpanel or a 125 amp subpanel?
 
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Leaflet

Active member
The inrush current on a Gavita 1000w DE is 40 amps. I think (check with your electrician) that you could have all of them on a single 40 amp circuit as long as you made sure they turned on at different times.
Your mini-splits will require separate circuits. Don't forget your outside disconnects, either.
 

pyrolysis

New member
The inrush on the Gavita 6/750 Pro is negligible. If you want to ball out you can get the EL1 controller which will give you a “sunrise/sunset” feature. But the ballasts themselves are soft start even without the controller. I’d run a 30a to be safe. With 10 awg wiring. As far as the mini splits go, the manual will tell you the minimum size overload protection. Don’t go less than that. It totally depends on the model of your mini splits though. Look into a split system with one outdoor unit and two indoor heads. Also don’t forget that things like pumps and air pumps and shop vacs etc take up quite a bit of current.
 

rives

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Entire house garage will consist of a Veg Room, Flower Room, and separate Drying room! Planning on running 2 mini-split AC units and a portable unit. one for each room unless otherwise suggested.

Planning to run four Gavita 1000 Watts DE in the flower room.. or maybe even just 600 watts.. for four big plants in PPK.. 600 watts HID @ 240 volts = 2.5 amp
They are 240-volt gavitas that means each light will need 4.16 amps. (1000 divided by 240)... So I'd want all four gavitas on a 20-amp breaker right? not a 25- amp?

and if the mini splits get their own 20 amp breakers @ 240 volts does that mean does that mean they use 40 amps total or 20 amps? Trying to figure out if I need a 100-amp subpanel or a 125 amp subpanel?

You are under-rating your load. The fixtures will have inrush that far exceeds the nameplate wattage, and the ballast itself consumes power that isn't included in the lamp wattage. Usually this will be an additional 8-15%. By code, you are limited to 80% of a circuit breaker's rating for loads that are energized for more than three hours (16a on a 20a breaker).

All of the equipment downstream of a breaker needs to be sized to withstand the full breaker rating, so if you use a 30a breaker, then the cord, plug, receptacle, etc. all has to be rated for 30a. Running 15a breakers with two lights per circuit, using standard cordsets and receptacles would be my choice.

The total for the A/C would be 40 amps. The same 80% rule for the main breaker applies, so the panel main and feed needs to be sized for that. Installations almost always change, give yourself room to grow - it's far cheaper to do it once.
 

pyrolysis

New member
You are under-rating your load. The fixtures will have inrush that far exceeds the nameplate wattage, and the ballast itself consumes power that isn't included in the lamp wattage. Usually this will be an additional 8-15%. By code, you are limited to 80% of a circuit breaker's rating for loads that are energized for more than three hours (16a on a 20a breaker).

All of the equipment downstream of a breaker needs to be sized to withstand the full breaker rating, so if you use a 30a breaker, then the cord, plug, receptacle, etc. all has to be rated for 30a. Running 15a breakers with two lights per circuit, using standard cordsets and receptacles would be my choice.

The total for the A/C would be 40 amps. The same 80% rule for the main breaker applies, so the panel main and feed needs to be sized for that. Installations almost always change, give yourself room to grow - it's far cheaper to do it once.

All really good points. Especially about giving yourself room to grow. In my experience, you always will end up wanting more.
 

MrMMJ

Member
It's important to realize that amp ratings for 240v are PER LEG, not total draw. A light drawing 9 amps at 120v doesn't magically run that same light at half the input. The amp draw is divided between 2 opposite phase legs. ( 4.5 x 2 )


Add the rated current draw of every single device on your planned sub-panel (120v at face value, 240v x 2 ). This amperage should be no more than 80% of the sub-panel size.


AC's need their own dedicated circuits. If the unit calls for a 20a two pole breaker, it's probably drawing around 25+ total amps. ( 10 to 15 per leg ).



More, lightly loaded circuits for lighting are better than a few, heavy loaded circuits. It's possible to put 4 1000w lights on a 20a 240v circuit ( approx 18a per leg ) but 3 is better. Running at near the rated capacity is more dangerous and causes more heat build up in the breaker and the wiring. ( Fun fact : breakers don't read amperage, they operate by reacting to temperature )


Finding the help/advice of a good electrician you can trust is invaluable. A carpenter, roofer, sheetrocker, painter, etc., can do lousy work and probably never hurt anyone. Lousy electrical work can cause death and destruction ! It's a very complicated trade that shouldn't be taken lightly. I did it for 13 years, but my last day in the trade was in '93, so it's been a while....
Good luck !
 

Lyfespan

Active member
with DE fixtures we always plan for 8 amps per fixture on 240v this takes care of SLA and is plenty for RLA easy, only run 2 fixtures on each 20amp 240v. 12ga circuit.
 

pyrolysis

New member
inrush? you guys mean SLA and RLA

Yes. When I went to trade school it was referred to as “inrush” since you could be talking about either SLA or LRA depending on the situation. RLA is just the theoretical max amp draw. LRA being locked rotor amps and SLA being starting load amps.
 

Lyfespan

Active member
Yes. When I went to trade school it was referred to as “inrush” since you could be talking about either SLA or LRA depending on the situation. RLA is just the theoretical max amp draw. LRA being locked rotor amps and SLA being starting load amps.

SLA= starting load amperage
RLA= running load amperage
 
ok so with the 80% of max amp rule... If the main electrical panel has a 100-amp breaker which will be feeding the new subpanel, does that mean the main breaker in the subpanel shouldn't be higher than an 80-amp? or is it okay to have a 100-amp subpanel hooked up to a 100-amp breaker as long as the subpanel's breakers don't exceed 80 amps total?


Going to hire a electrician but would like to plan out the circuitry and parts list myself if possible
 

pyrolysis

New member
ok so with the 80% of max amp rule... If the main electrical panel has a 100-amp breaker which will be feeding the new subpanel, does that mean the main breaker in the subpanel shouldn't be higher than an 80-amp? or is it okay to have a 100-amp subpanel hooked up to a 100-amp breaker as long as the subpanel's breakers don't exceed 80 amps total?


Going to hire a electrician but would like to plan out the circuitry and parts list myself if possible

You can put a 100 amp feed to the sub panel which has a 100 amp breaker. You are only supposed to load the branch circuits of the sub panel to 80% ampacity.
 

rives

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For sure, we are on the same page. All I meant was RLA is a theoretical number, similar to the EPA’s MPG calculation.


Actually, no, I'm not on the same page with this.

"Starting load amperage" is typically the current seen while a load a load stabilizes, as in a motor load being accelerated up to speed. High-inertia motor loads can easily pull from 300-900% current while the load accelerates.

"Running load amperage" is when the current has stabilized after the above.

"Inrush current" is the instantaneous peak seen for a few cycles while the the circuit is energized from a zero-power state. With circuits that are heavily capacitive such as electronic ballasts, or with motor and transformer loads while the windings saturate, this current can approach short-circuit levels.

https://www.sunpower-uk.com/glossary/what-is-inrush-current/
 

Lyfespan

Active member
Actually, no, I'm not on the same page with this.

"Starting load amperage" is typically the current seen while a load a load stabilizes, as in a motor load being accelerated up to speed. High-inertia motor loads can easily pull from 300-900% current while the load accelerates.

"Running load amperage" is when the current has stabilized after the above.

"Inrush current" is the instantaneous peak seen for a few cycles while the the circuit is energized from a zero-power state. With circuits that are heavily capacitive such as electronic ballasts, or with motor and transformer loads while the windings saturate, this current can approach short-circuit levels.

https://www.sunpower-uk.com/glossary/what-is-inrush-current/

:thank you::tiphat: i was trying to point the facts out
 

Lyfespan

Active member
Actually, my point was that you were incorrect here -



SLA, RLA, Locked rotor amps, and inrush all refer to different, very specific load characteristics.

inrush SC SLA

RLA LRA

guess you could say im wrong? was just trying to make the connection between Cannadian units of reference and american :tiphat:

i would never even bring up LRA in a light discussion, and i guess the technical jargon for starting an electronic ballast is SC, but i swear SLA was acceptable too ?
 

rives

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inrush SC SLA

RLA LRA

guess you could say im wrong? was just trying to make the connection between Cannadian units of reference and american :tiphat:

i would never even bring up LRA in a light discussion, and i guess the technical jargon for starting an electronic ballast is SC, but i swear SLA was acceptable too ?


You corrected our usage of "inrush" to starting current or starting load amperage. They are not the same.

Inrush, as I said above, only lasts a few cycles of the sine wave. Starting current lasts until the load is stable and can be limited by the circuitry if it has a "soft start" feature - inrush cannot. It is the transient that takes place when the capacitors charge up and before the circuitry is fully functional. It can raise hell with other electronics on the same feed, including everything that is on the load side of the transformer bank that feeds it. If your lights are causing your neighbor's computer to restart every day at the same time when they turn on, it is due to inrush, not the starting current. This is one of the reasons that I suggested limiting two ballasts to each circuit.

No, locked rotor amps are not relevant to a lighting discussion. I mentioned it because it was brought up in the above discussion.


*edit* From the link that I provided above -

Inrush current is the instantaneous high input current drawn by a power supply or electrical equipment at turn-on. This arises due to the high initial currents required to charge the capacitors and inductors or transformers.
The inrush current is also known as the switch–on surge, or the input surge current.

At turn-on, the discharged capacitors in power supplies offer low impedance that allows high currents to flow into the circuit as they charge from zero to their maximum values. These currents can be as high as 20 times the steady state currents. Even though it only lasts for about 10ms it takes between 30 and 40 cycles for the current to stabilize to the normal operating value. If not limited, the high currents can damage the equipment in addition to producing voltage dips in the supply line and causing malfunctioning of other equipment powered from the same supply.
 
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