Practical Volt/Amp/Lighting Help

[slondon]

Commercial buildings should have 20A circuits. If the outlets have a horizontal slit along with the usual vertical one for the neutral conductor the circuit is almost surely 20A. The only way to be sure though is to identify the breaker for the circuit and verify its capacity for yourself.

If you want to get chapter and verse from the National Electrical code Google NEC branch circuits 20A and OCPD (over current protection device). You still have to look though.

 

[Homunculus]

No way to tell really. There are no devices that can tell you the maximum current of an outlet either. You might just have to ask the management or custodial department what breaker size they are using for that area. I doubt they put anything more than 15A in though. Also beware that they might have only one circuit for each room too..

what the hell... you serious? why would that be?

 

[Homunculus]

Commercial buildings should have 20A circuits. If the outlets have a horizontal slit along with the usual vertical one for the neutral conductor the circuit is almost surely 20A. The only way to be sure though is to identify the breaker for the circuit and verify its capacity for yourself.

If you want to get chapter and verse from the National Electrical code Google NEC branch circuits 20A and OCPD (over current protection device). You still have to look though.

hmm you say almost certainly 20a other guy says almost certainly no higher than 15a ...whom to believe? lol

 

[slondon]

hmm you say almost certainly 20a other guy says almost certainly no higher than 15a ...whom to believe? lol

You did notice the distinctive duplex outlet, right? What I mean is that those outlets are designated by the code for 20A circuits. Now, nothing stops some doofus from installing one on a 15A circuit but if it's a commercial building it probably was wired by a professional electrician and an electrician wouldn't install that outlet on a 15A circuit.

The only way to be absolutely certain is to identify the circuit back at the panel and see for yourself. If for some reason you can't get to the panel you could pull an outlet and see if it is #12AWG. Once again, that doesn't prove the breaker is 20A but it is good evidence. It is certainly true that 14 gauge wire will not handle a load above 15A, so if that's what you find forget the big light.

One thing in your favor is that your 2000W incandescent's load is purely resistive and has no reactive component.

BTW, I'm a gaffer not a licensed electrician. I wouldn't pretend to give anything other than suggestions and you should take them as such. Identify the branch circuit at the service panel and see for yourself.

 

[Homunculus]

slondon thanks. can you please elaborate on what is resistive and reactive? What the difference is?
by the way any idea where circuit breaker panel would be in a class room type setting are those panels usually HAVE to be in the same room? Or are they in some master control room that only janitors and such have access to elsewhere in a maintenance section of the building?

thanks

 

[maplecap]

slondon thanks. can you please elaborate on what is resistive and reactive? What the difference is?

I suspect that he is referencing reactive ballasts, like a non-Power Factor Corrected ballast for HMI or fluorescent fixtures.

Some basics:
http://en.wikipedia.org/wiki/Power_factor
http://en.wikipedia.org/wiki/Electrical_ballast

by the way any idea where circuit breaker panel would be in a class room type setting are those panels usually HAVE to be in the same room? Or are they in some master control room that only janitors and such have access to elsewhere in a maintenance section of the building?

Dude—scout the location ahead of time or when you arrive. How would we know where the breaker box is for your location? That should always be one of the first questions you ask of a site rep, contact or bldg maintenance person.

 

[j1clark@ucsd.edu]

slondon thanks. can you please elaborate on what is resistive and reactive? What the difference is?
by the way any idea where circuit breaker panel would be in a class room type setting are those panels usually HAVE to be in the same room? Or are they in some master control room that only janitors and such have access to elsewhere in a maintenance section of the building?

thanks

The 'only' way to find out what the rated amperage is for the circuit in question, is to find the breaker box, and read what the breaker value is. Even then that will not absolutely guarantee that the circuit is up to snuff... but at least when you are sued you can blame the electrician who wired the place... or does it mean that there aren't a bunch of things hanging on the circuit, which when you add your load, will cause the breaker to trip.

When I use to do more weddings, being the Ace Gun Bearer for Bwana Lady Photog Extraordinaire, it was my job to check out new venues for power, because the Bwana Lady like to use big strobes. We did have an occasional 'brown out' in some older houses, even though the strobes where 'rated' for 15 A. Thats because during the strobe recycle time the capacitors in the box are drawing down a number of amps to recharge...

The only time we 'blew' a fuse, was when we plugged into a circuit that the band had plugged into elsewhere, and it was not 'clear' how we got on the same circult... it was in a older venue, so perhaps the owner cheated, or just didn't bother to run a new circuit, and just had the electrician 'add on' to the old one...

The other 'dangerous' ligthting activity Bwana Lady did was shooting underwater photos of brides, or whoever, and we would pump about 5-7K Watt-seconds of power into the water. So we had a bank of strobes setup, powered via a 'ground fault' detecting circuit, and cordoned off to not have any traffic in the area. Since this was a somewhat sedate type of shoot, there was not to much in the way of splash from the water into the 'strobe/death' zone. However, on some occasions we did shoot in out door pools, and so everything was tied down so the wind/breeze could not tip something over, and into the pool... (we also had spotters in the pool in case anyone got in to trouble...)

 

[slondon]

slondon thanks. can you please elaborate on what is resistive and reactive? What the difference is?
by the way any idea where circuit breaker panel would be in a class room type setting are those panels usually HAVE to be in the same room? Or are they in some master control room that only janitors and such have access to elsewhere in a maintenance section of the building?

thanks

Maplecap is right, but you know, my comment was just a throwaway and not useful to you in this situation so ignore it.

It's also right that you need to to a technical scout of your location and find out things like where the main breaker panel is. I also often find that outlets are not hot and you need to find more than one branch circuit, so take your circuit tester, meet the maintenance guy -- schools have electricians -- and check things out.

If your lighting is ad hoc it won't be as good as if you plan it ahead of time.