How Many Lightbulbs on a Circuit? USE OHM'S LAW!!!

[@larrybland007]

Bro I learned more from you Channel in a month than I have at work for a calendar year!

[@mikesmoth-v4w]

you have a talent for this. Great teacher .

[@kl8295]

Really appreciate the following here man: (1) Video is under 5 mins; (2) drawn example; (3) kept it simple (4) added an asterisk to explain the "real world" code scenario. Incredibly helpful! I encourage you to do more of these short videos connecting the install to the design.

[@scrublet2017]

Learned this during my electrical course a while back. This was a great refresher. I also liked how you added the code rule

[@njphil1279]

This applies for any basic resistive loads but heating elements (old school light bulbs, toaster ovens, etc..)change resistance as they age and heat up. Naturally if the resistance changes, the wattage follows. Guess that's why you use the 80% rule. Another good thing to mention is the new LED bulbs can't simply follow your rule because the power supply consumption, either discrete or within the bulb itself, needed to drop the volts to run the LED isn't included in the bulb rating. Although negligible, a 4W LED might consume 12W of actual power. Good stuff here. I'm a EE, mostly digital, and grew up on this stuff. My kid would be just like you had he follow my profession and not gotten into software. Nice how you teach the noobs on how to do shit the right way. To many hackers out there that don't know what they are doing

[@KevinCoop1]

The reason for 80% is that circuit breakers are rated at 100% for non-continuous and 80% for continuous loads. Lights are considered in NEC as a continuous load. 3 hours usage is the amount of time considered. One should always use published running amperes on luminaries when doing calculations. Not the wattage of the lamps as you said. That is unless you are using incandescent lamps. No ballast, driver, or power factor to consider.

[@kaminoshi713]

I subscribed off of an earlier video, I’m already appreciating the choice and the content.

[@jacobwalkup4592]

Can you do a video on digital multimeters vs clamp meters? And which you need for what you do.

[@ReggaeRedeemer]

This one is super crucial for someone that is starting to do small side work jobs

[@luismatias2910]

Good info. Man thanks for share you Kwnologed

[@slaugh77ify]

You are a very good teacher. Thank you

[@MrAcacio]

Thank you. I will remember to do that before install a lamps. Couple months ago, I was asking this question and I try to research on the web, but you are the Man. The best and simple explanation. Thank you brother.

[@MiddaJoice]

Great video, i feel like i learned more in 2:59 then i did all day in apprentice school.

[@TechWizard312]

Short and informative. I like it. Adding to favorites.

[@MagneticPerturbation]

Good catch on the 80% continuous load requirement in NFPA 70. I started to type up a comment of reminder just as that ad hoc text block came up. Understanding basic algebra and going through the longer training (including math theory) are necessary a priori to the shortcut methods imho but the shortcuts definitely have their place. Like in depth code classes are important before you can default to Ugly's for brevity. Keep up the good work and never stop learning. Liking the channel.

[@TheLoboindio]

You had me going there for a second I thought you were going to drop the ball. But then right at the end. U drop the 80% rule. Good vid!!

[@ceasarcastaneda1653]

Can you make more videos like this to help out those starting to work with electricity. This was helpful.

[@TheOGize]

Would you find how many lights on a circuit by the bulb your installing or the maximum allowed wattage bulb for that fixture. For example recessed can lights accept 60 watt bulbs but you can also install a 12 watt LED Trim.

[@Kon6ience]

BIG THUMBS UP, LOVE THE CONTENT/ EDUCATION. I appreciate you as much as my teacher, respect 🫡🦾

[@nafizkhan7748]

Thanks for the video. Another thing to note is the inrush current which could cause nuisance tripping..

[@getwrxed6218]

That was an amazing video dude, short simple and straightforward

[@sa31489]

That was so helpful. Thank you.

[@gamingx6599]

Nice really short and simple! Thanks

[@zanelewis1370]

Love the content brother! This may be petty but i think these explanation type vids might benefit even more without the background music. Thanks again for all that you do

[@JoseRodriguez-ck2gi]

how did you get started in the trade?

[@sambromley7394]

Awesome video. Id like to see something on bending. I have some trouble with back to back 90’s. Or perhaps some tips on how to keep bends aligned when doing air bends?

[@MontyRL]

I always use the variable V instead of E. Not only was I taught this way. But it's much easier. Thanks for the video tho. Cleared up some confusion

[@realSamAndrew]

Me too. But I always wondered why they can't use A or C instead of I?

[@anonymousperson4363]

More letters to remember. PCV does not sound easy to remember. Maybe PAV and VAR isn't too bad.

[@RE-ee3ud]

Thanks very helpful!

[@charlespatt]

I learned the charts when I was 12, never forgot them for the next 54 years. Also, I found could always remember the order of the letters because, well, PIE spells pie. And EIR happens to be in alphabetical order. It was helpful for a 12 yr old kid who just got his ham license.

[@dylangarrant3027]

Another good video

[@franciscoc2524]

First year apprentice that’s just learned ohms law… thanks for giving me an in-field example

[@richlebarron8957]

Amazing, I can use all the help I can get with tricks like this.. this is the type of stuff You learn in school or from people twice your age...

[@johnboyd1167]

Short sweet and to the point

[@GorillaStunter]

Hey homie was wondering if you could do a video on motors? I’m about to test for journeyman and would like some deets on motors thank dude love the channel…… you going to sell those electricianU coffee mugs

[@Clyde1996]

I woke myself up this morning thinking about a home reno and the microwave/range hood combo that the customer is having installed, I grabbed my phone and did quick Ohm's law math to make sure I had the right breaker and wire installed. I did, woke myself up for nothing but it's always good to double check.

[@RobinSmithSongs]

Great that you represent Ohm's law with E=IR instead of V=IR but, P=Power which is measured in Watts. When I was in college there was no such word as 'Wattage' !

[@lex52110]

Awesome video

[@fisforfriendship6093]

the way i did it was 400w divided by voltage 120 and i got 3.33 amps per light divide my 20 amp breaker by 3.33 and i got 6 lights i can put on that circuit. like justice said 80 percent of of 20 amps is 16 amps or 80 percent of my answer 6 is 4.8 or 4 lights?

[@TheBoyGoku]

and im actually doing the site lightning rn this came in an amazing timeeee

[@goinbananers]

code book has all the formulas for lightning BUT its so confusing

[@KevinCoop1]

When doing lighting branch circuits or load calc. that has a ballast or a driver(anything other than incandescent) use the luminaire running amps, not just the lamp watts. In the example shown, a 400w MH @120v is 4 amps. 4x130=480. Use 480. This accounts for ballast loss and any power factor.

[@betocastillo2681]

Good video bro.

[@jabarijones2171]

Thanks Man your awesome

[@Macula223]

What happens if in your main electrical box of your home, the ground wire is temporarily disconnected, and is it feasible to disconnect it temporarily to make an adjustment.

[@wizard3z868]

it is or should be ok to disconnect the ground wire as it really should never carry a load but a lot of times it dose you can chk it but if i where to disconnect it from main panel it shouldnt matter provided the neutral connection is solid as why we bond both at first disconnect.( i discovered loose neutrals before by reading high current flow thru the ground yikes) if its a sub all other grounds cld potentially be live and after main feed ground is disconnected they should be treated as such

[@TomCee53]

Probably ok, but why take a chance. I know it can be a bit of bother to rest microwave clocks,etc. A bigger bother would be a visit from an EMT.

[@MrRogsmart]

Nicely done. A good simple explanation of something that mystifies the hell out of a lot of people.

[@MikeMeierJapan]

Even thou this was a shot one, I just needed this formula today and was surprised to see your video on this. Coincidence?

[@sparkymyrl]

You also need to get the idea. A 400 watt metal halide lamp with the ballast Pf, eff, the input wattage will be 455 watt average running current and higher with the cold start, starting current. When designing high discharge lighting circuits, you need to take this into consideration.

[@googleevil9553]

Always a wise guy

[@williambrandondavis6897]

That's completely variable based on ballast and bulb design. Some use less and some more. Its common for growers to test different combinations to find the highest output they can.

[@sparkymyrl]

@@googleevil9553 Thank you.

[@ArizonaArmwrestlers]

You should also mention that this pie wheel does not work for 3-phase circuits

[@ikerivers1795]

They do but you have to add the square root of 3

[@ArizonaArmwrestlers]

@@ikerivers1795 you do not add the square root of 3. You multiple your line to line voltage by the square root of three. Then you also must take into account power factor. After you account for that, the you must account for the NEC depending on application, for most instances another 1.25

[@ikerivers1795]

@@ArizonaArmwrestlers apologize for the verbiage. Didn’t mean add in the mathematical sense. But you are correct with Power Factor. Forgot that. I was grilling some steaks. Come to think about it you are also right about the pie wheel itself NOT working for 3 phase. I just use the equations. Shit!!! You are correct the whole way through and I am wrong. Thanks for the correction. Blessings to you and yours!

[@unoreversecard3302]

My journeyman couldn’t answer this question for me so thank you

[@fcoc2203]

some people never learn the technical part,,, but they are good pipe benders for 25 years

[@DieselWeasle]

I am learning new things. Damn maybe I should look into electrician school.

[@PacRimElectric]

120v though must be a home owner association. If we did at 277 you can 13 lamps....well because of the ballast more like 10

[@illestofdemall13]

Not all parking lot lights are 277. Some are 120 some are 240 as well.

[@PacRimElectric]

@@illestofdemall13 that is very true or our 480

[@KevinCoop1]

@@PacRimElectric You need to clarify what your circuit size is before telling how many can go on a circuit.

[@PacRimElectric]

@@KevinCoop1 very true

[@goinbananers]

Incandescent watts or LED watts? And where is Holmes in this equation?

[@edward4919]

Solid!

[@jburnes41]

the key was 80% of the load of the breaker

[@MrMaxyield]

If you call yourself an electrician you should have ohms law memorized...!! 💯💯💯✅

[@pajarovago2283]

Nice

[@mikefromflorida8357]

Thank you for using E for voltage and not the layman’s V.

[@brianbranson2306]

most people dont think about this when it comes to chandeliers. they want to up the bright, so they start screwing in 60W bulbs in a unit designed for 40W and cant figure out why there dimmer switch is melting.

[@user-nh3gu1ge3d]

So get a 100 watt equivalent LED bulb that uses 8 watts. Anyone who uses incandescent light bulbs in a first world country is an ignoramus.

[@brianbranson2306]

@@user-nh3gu1ge3d show me a an led that l.ooks like a candle.

[@user-nh3gu1ge3d]

@@brianbranson2306 I don't know if you consider those "candle-like" but they look like the incandescent bulb version to me, are chandelier bulbs, and use 4 watts. So, yeah. They look like a candle as much as the others I guess. I assume whatever form factor you desire in incandescent they also make in LED. Also not sure why anyone would want to use a 400 watt light fixture when they could get the same light for a 90% power reduction.

[@MrYuske1985]

Everyone loves a quickie

[@gabewhisen3446]

So a 15a circuit should only be loaded to say 13a looks like -2% is that the formula

[@rodolfovesga979]

Cool video lol

[@justcommenting4981]

Wow. They idiot proofed the formulas. The practical work of trades does a lot to making subject matter more teachable and understandable. Beard look is solid thicc and tight here too, so good work there. All around great channel.

[@garbo8962]

While wiring up machine shops tool& die shops & injection molding shops never went over 12 amps on a 20 amp lightning circuit due to they always added luminares around machinery amd over work benches. Now that every luminare should be LED"S you can have a lot more luminares on a circuit. Gets bad with 277 volts where clowns install all of the say25 luminares in a room on only 1 circuit breaker. Have a short have no lighting. These 2 pie charts and KVA formula for transformers are used 99% of the time ny electricians.

[@devinmalison]

Does math get more complex than this? (I’m not saying this is complex)

[@artomix7]

Only a little bit more with some very simple trig but thats about it for the electrician side of things

[@elena6516]

math in general or electrical math? 3-phase math involves trigonometry and frequency in very slightly more complex equations. Not difficult if you're good at math.

[@tedlahm5740]

Try adding four (4) resistances that are in parallel. Need this because all 120 volt duplex receptacles are in parallel.

[@juliansanchez2536]

Cool

[@richardcranium5839]

laws were made to be broken. i'm so old these were not wheels they were triangles.

[@MagneticPerturbation]

I heavily relate to this comment but I have one caveat. I'd say rules are made to be broken but laws tend to be immutable.

[@ikerivers1795]

Only the left one is Ohm’s Law. The right side power wheel is Joule’s Law.

[@tedlahm5740]

Yes, my understanding. Perhaps another source of information needed?

[@altuber99_athlete]

Two corrections: • Ohm’s law is not P = V I. • Ohm’s law is V = I R when R is constant, but not when R is variable.

[@jonmolina948]

The beard came back quick.

[@KameraShy]

B = T x R

[@richardcranium5839]

how many light bulbs can go on a circuit??? how many elechickens are there to screw them in?

[@loucinci3922]

Twinkle twinkle little star, power = I^2 R

[@tedlahm5740]

voltage squared divided by resistance. exactly

[@danjackman5100]

I may be wrong but seems to me 5 lights would still be at 80% of 2400

[@travisbuildsthis8673]

It equates to 4.8…. Must round down to four

[@TomCee53]

Yeah, 5 lights would be 83 1/3 %.

[@oldskoolwayy]

What I dont understand is he still ended up using numbers to figure it out and not the letters..

[@realSamAndrew]

Is that a joke?

[@johnstancliff7328]

and what happens when they go from metal halide to LED? boy do they have more power....

[@goinbananers]

I want some PIE

[@user-nh3gu1ge3d]

The more practical answer for your home in today's age is: basically as many as you want*. (*provided you are using what you should be using, LED, CFL, etc). These bulbs draw so little power, typically in the 8 watt range, that this question is largely irrelevant. The smallest home circuit is typically 15 amps, at 120 volts (in the US) which equals 1800 watts. Even with the 80% rule, that's 1440 watts divided by 8 watts per bulb is.... 180 lights. Of course, it's not a bad thing to know but still. Just some perspective of actual power draw with modern bulbs. Anyone who uses 100 watt incandescent bulbs today is a fool.

[@chrissean6099]

1st

[@vbottoni]

hey this is all you need to be an electrical engineer ;)

[@BeerkegGarage]

Beard, gotta keep the beard bro you have more power with it! You look 10x more blue collar and everything you say sounds better with the beard

[@Bradley-tx6ed]

I never used the charts just give me the equations and ill flip them around myself

[@elena6516]

Look at the big brain on Brad! Jokes man, I do the same. Understanding is better than memorization.

[@charlespatt]

I learned the charts when I was a kid of 12, never forgot them (I'm 66 now). The thing is, I've mainly only been a hobbyist and not worked with the formulas that often, so when I need them, the charts help confirm what I may have been thinking.

[@Inferior_Machines]

Volts don’t equal watts man. This is seriously misleading people. Force doesn’t equal energy. You should be ashamed of yourselves at this point! This is not how ohms law works electricity. Come on! When did KZbinrs change the definition of volts in electrical engineering.

[@Doc-jw4iy]

He didn't finish the math 2,400x.80=1920 1920 divided by 400 =4.8 Total lights 4 not 6