Growroom Electricity and Wiring

[Jhhnn]

Go to the meter panel & determine the capacity of the main breaker. Depending on where you live there may not be one w/ work that old. If there's not then power comes directly from the meter to the leads at the top of the bussbars. From the diagram, that means the top half would be hot all the time. In any case, You have a max of 125A available & only 60A available on the lower half of the breakers.

Make a list of the large electrical loads- Electric dryer, baseboard heaters, water heater, stove, refrigerator, freezer, furnace, air conditioner & anything else that might use a lot of power. Measuring the current can be tricky because the load can change thermostatically in some so the best answer is to read it from the nameplates on the devices or from the manuals. Measure the lighting load w/ everything on. Map these devices to the breakers in the panel. Label the panel while you're at it.

240v loads are self balancing on the bussbars while 120v loads are not. Using your map & the bussbar diagram, determine if the 120v loads are relatively balanced on the bussbars. Make it so as well as you reasonably can. Add up the loads on each bussbar, subtract each number from 125. The smaller number of the two is excess capacity at the upper bussbars you can use for your grow circuit.

Once you have that stuff figured out you're in the position to make educated choices.

 

[rives]

To clarify a bit more, the 125a is the maximum that the panel is rated for - we do not know what it is actually fed with until you see what size breaker is feeding it. There should be a main breaker since this panel is remote from the meter, and if it were fed directly (no breaker) the feeder wires would be unprotected other than the transformer fusing. It would also be helpful to know what size wires the panel is being fed with. The size should be printed on the insulation.

Without knowing what your connected loads are, it is impossible to say if the panel will be adequate or not, but from your readings so far it looks pretty iffy. Gas dryer, range, water heater and furnace or electric? The labeling on the breakers is obviously not correct and you need to nail down what you have per Jhhnn's directions above.

 

[plutosmoke]

Hey rives, I've had in the past, twice lost one of my phase and the elec. comp had to come out and fix it. Seemed like they just reset a switch at the green transformer box.

My question is, is it an unbalanced phased that is causing it or could it be a spike of amperes from my usage?

 

[rives]

Hey rives, I've had in the past, twice lost one of my phase and the elec. comp had to come out and fix it. Seemed like they just reset a switch at the green transformer box.

My question is, is it an unbalanced phased that is causing it or could it be a spike of amperes from my usage?

If you just lost one phase and it was on the utility side, you probably blew the fuse on that leg. Fuses will blow on individual phases whereas a breaker should open them all at the same time. Fuses are much more commonly used in utility distribution because they are far cheaper to install.

I would suspect that you, or you in combination with your neighbors if they share the transformer, have a very unbalanced load & then you spiked it. Transformer fusing is usually set pretty damn high since the utilities don't necessarily have to comply with code, and their transformers are also typically loaded much heavier than industry would do. They get away with it because the transformers are in open air and most heavy loads are pretty transient in nature (at least in regard to burning up a transformer).

 

[plutosmoke]

Thanks for the information rives, that clarifies why one of my leg gave up on me twice!
Is there a tolerance percentage difference between the two legs that i should keep an eye on? Does that tolerance increase/decrease as amperes usage goes up or down?

I am running all 240v for lights and ac but I do have a 120v 12kbtu for veg and I'm thinking that is my culprit for the imbalance. I tried to balance it out with other 120v inline fans but I would really like to know the danger levels for the imbalances. Thanks Rives!

 

[rives]

It's really hard to say at what point it can become a problem on a single-phase residential system - the issue is that a heavily-loaded phase creates a voltage drop on that phase, the voltage drop then creates a higher amperage level from trying to maintain a given wattage (Volts x amps = watts), etc. A well-designed 3-phase industrial system tries to stay under 1.3% at the load and 2% at the control center. Code allows up to 5%, but the motor load needs to be de-rated or the life of the motor will be impacted.

As a rule of thumb, the longer-term, substantial loads on 120v should be balanced as well as possible between the two phases. Short term loads are likely to have little effect. I would get a clamp-on ammeter and measure each of the wires coming into/out of the main breaker several times a day when you know that you are loaded up. The other thing that you can do is to shut off the main breaker and measure the incoming voltage with a digital voltmeter. If you have a neighbor that shares the transformer, and he shares our hobby, the problem might be reflected on your service and you could potentially be compounding the issue if you are heavily loaded on the same phase that is coming in low. A voltage imbalance can be magnified 6-10 times when it is reflected in the current imbalance.

If you have 12kw of 120v load (that's 100 amps) all on one phase, there is no way in hell that you are going to balance it with your fan load!

 

[Jhhnn]

Rives is spot on as always. One of the big advantages or running the lights or any heavy load at 240v is that the load is always balanced on the two service legs.

You can hook up a min max voltmeter & just leave it there for a day or few to check for voltage fluctuations.

 

[plutosmoke]

thanks Jhhnn and Rives

Also rives, I mean a 12k BTU ac for my veg room running on 120v and I try to balance it by throwing my fans on the other leg. Not sure if the small differences makes any differences. I will definitely have to check my voltages coming in. Thanks A lot!

 

[plutosmoke]

If you downsize the existing 30a breaker to 20a and feed the downstream circuitry with that, yes, it would be safe. This will work if you plan on running your 3kw on 240v, but if they are fed with 120v, the current will be too high. The 80% rule would allow you 16 amps (you are only allowed 80% of the breaker rating for continuous loads, which are defined as anything over 3 hours in duration). You also have to account for the ballast losses, so an estimate of an additional 10% load equals 3300 watts, or 13.75 amps at 240v.

Another option would be to keep the existing 30a breaker, feed the Intermatic with that, and then feed into a small sub-panel downstream of the timer. Small subs are available for under $20, and then you could break out the circuits with individual protection for each receptacle.

Keep in mind that the Intermatics, while bulletproof, are motor-driven and cannot be battery backed (there are some electronic models available, but they aren't nearly as common), and will lose their setting if the power goes off. They also have poor resolution because of the timer flippers, but good repeatability. An option would be to use a 40a power relay and control it with a conventional battery-backed digital timer.

This is the power relay that I normally recommend - http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A

Hey Rives, is there a specific reason you like this contactor?
Is it durable and does it last under heavy load?

I had contactors in the past that worked for some time but the contacts in it ended up getting welded together and caused my lights to not turn off. Of course I bought those danm things on eBay. I believe it was a counterfeit and the medal-gold-color contacts on it wasn't real copper.

I bought the contractors you recommended and see the same copper contacts.

Please tell me you've used those contractors for years without problems as long as you stay under 40amps

 

[Jhhnn]

Hey Rives, is there a specific reason you like this contactor?
Is it durable and does it last under heavy load?

I had contactors in the past that worked for some time but the contacts in it ended up getting welded together and caused my lights to not turn off. Of course I bought those danm things on eBay. I believe it was a counterfeit and the medal-gold-color contacts on it wasn't real copper.

I bought the contractors you recommended and see the same copper contacts.

Please tell me you've used those contractors for years without problems as long as you stay under 40amps

I'm highly experienced with contactors & bought one of those on Rives' advice. It's an old school beast, carrying an industrial rating of 50,000 cycles at full load. I have no doubt that it would do it, either. You might weld the contacts shut with a dead short on a big breaker but that's about it.

The contacts are gold flashed silver/cadmium oxide. From here-

http://www.automationdirect.com/static/specs/pr40powerrelays.pdf

If you were trying to get the full rated life it would be considerably de-rated for inductive or capacitive loads. 50,000 cycles once a day is 137 years so no worries.

 

[plutosmoke]

I'm highly experienced with contactors & bought one of those on Rives' advice. It's an old school beast, carrying an industrial rating of 50,000 cycles at full load. I have no doubt that it would do it, either. You might weld the contacts shut with a dead short on a big breaker but that's about it.

The contacts are gold flashed silver/cadmium oxide. From here-

http://www.automationdirect.com/static/specs/pr40powerrelays.pdf

thanks Jhhnn!

I bought 2 of the one Rives recommended, and will install tomorrow and probably order more!

Thanks for your input!

 

[_tessarecting]

What does it mean if an 8 lighter on a month old 40amp breaker keeps flipping off once a day? Busted? Upgrade to 50?

 

[rives]

What does it mean if an 8 lighter on a month old 40amp breaker keeps flipping off once a day? Busted? Upgrade to 50?

Any other loads on the circuit besides the lights?

If you add in ballast losses at 10%, which is just a ballpark - yours could be substantially more or less, you are at +/-37 amps. Code for continuous loads (anything over 3 hours in duration) calls for de-rating the breaker to 80%. This puts you at 32 amps maximum on your 40a circuit. It looks like you just demonstrated why: manufacturing tolerances, ambient conditions, line condition at sustained high loading, etc can all combine to give you nuisance tripping.

Assuming that you are at around 37a, you can either look around and find a specially-listed breaker that has been tested to run at full load continuously (they are available, but difficult to source), or upgrade the circuit.

Be aware, though, that there is more involved than changing the breaker out if the circuit was designed for 40 amps.

 

[_tessarecting]

Just lights (1000w @ 220v) on the 40a breaker (100a panel) and not much else on in the house. Goes off very randomly lately... the breaker feels kinda weak to the touch, as in the lever doesnt have a lot of snap to it, its mostly slide, unlike most ive used in the past. I wonder if the rain has anything to do with it.

 

[Dislexus]

Just lights (1000w @ 220v) on the 40a breaker (100a panel) and not much else on in the house. Goes off very randomly lately... the breaker feels kinda weak to the touch, as in the lever doesnt have a lot of snap to it, its mostly slide, unlike most ive used in the past. I wonder if the rain has anything to do with it.

Like rives said, too much juice.. DO NOT just slap a 50amp breaker on there, the wire may be too small to handle that juice and START A FIRE. (the caps+bold+underline are in case you're skim-reading because its important, don't want you to get hurt or busted because of a fire)

As to your weakened breaker question, breakers do wear out. Supposedly you're to change them out if they even flip once but fuck that. See, that current flowing through your breaker&wire is generating a magnetic field, when the current increases so does the strength of the field, which creates enough force pull the breaker open thus breaking the circuit, therefore the wire doesn't get hot from that excessive current and start a fire. So there can be mechanical wear on breakers that could make them flip at lower current draws when a lesser force from the magnetic field is applied.

But the root problem is your 8 lights are drawing too much current to begin with, causing the breaker to trip over and over, wearing it out.

 

[EastCoast710]

if hes running at 220v.. shouldn't he only be puling half that in lights?

 

[mowood3479]

8x 1000w @ 120=66.6666 amps
8x 1000w@ 240=33.333amps

 

[Jhhnn]

Like rives said, too much juice.. DO NOT just slap a 50amp breaker on there, the wire may be too small to handle that juice and START A FIRE. (the caps+bold+underline are in case you're skim-reading because its important, don't want you to get hurt or busted because of a fire)

As to your weakened breaker question, breakers do wear out. Supposedly you're to change them out if they even flip once but fuck that. See, that current flowing through your breaker&wire is generating a magnetic field, when the current increases so does the strength of the field, which creates enough force pull the breaker open thus breaking the circuit, therefore the wire doesn't get hot from that excessive current and start a fire. So there can be mechanical wear on breakers that could make them flip at lower current draws when a lesser force from the magnetic field is applied.

But the root problem is your 8 lights are drawing too much current to begin with, causing the breaker to trip over and over, wearing it out.

Just a minor quibble. Most household breakers are thermal-magnetic having two tripping mechanisms. The magnetic part trips with a short circuit while the thermal part trips if the load over time is too great, hence the 80% rule Rives mentions.

https://en.wikipedia.org/wiki/Circuit_breaker#Thermal_magnetic_circuit_breakers

 

[Jhhnn]

8x 1000w @ 120=66.6666 amps
8x 1000w@ 240=33.333amps

It's really more than that because of electrical inefficiency in the ballasts. Both of the 1000w mag ballasts I own draw 1140w at the receptacle. For 8 units, that's 38A @ 240V. Electronic ballasts are slightly more efficient but it's still likely over 36A.

Seven 1140w ballasts would draw over 33A, slightly above the recommended 32A.

 

[Dislexus]

One Wire Size Up Means Big Savings:

http://www.copper.org/environment/s...y-efficiency/education/archive/onesizeup.html