Is Residential Lighting Continuous?

[iwire]

This came up so why not start a new thread about it?

Are residential lighting circuits continuous loads?

How many people actually wire dedicated lighting circuits in dwelling units?

Continuous Load. A load where the maximum current is expected to continue for 3 hours or more.

I think a key word in there is "maximum" that says to me every light on the circuit would have to be expected to stay on for more than 3 hours at the same time.

I doubt I would say it is a continuous load.

In the same line of thinking considering we are putting motion sensors on almost all office lighting now do we still have to say office lighting is a continuous load?

[ September 08, 2005, 11:04 AM: Message edited by: iwire ]

 

[charlie b]

Re: Is Residential Lighting Continuous?

Since I offered the challenge for anyone to bring up this subject, I suppose I must offer my own opinion. Here it is: It doesn't matter.

 

[iwire]

Re: Is Residential Lighting Continuous?

Originally posted by charlie b:
Since I offered the challenge for anyone to bring up this subject, I suppose I must offer my own opinion.

Thank you

Originally posted by charlie b:
Here it is: It doesn't matter.

I agree.

Originally posted by charlie b:
We size the circuit, including the breaker and the conductors on the basis of 180 VA per duplex receptacle.

Minor point, the 180 VA does not apply to dwelling units, unless you want it to.

I can put a 100 (or more) receptacles on a dwelling unit circuit.

I do not see any of that changing your reasoning.

Originally posted by charlie b:
Or am I oversimplifying things?

Nope, simple is good.

 

[iwire]

Re: Is Residential Lighting Continuous?

Originally posted by iwire:

Originally posted by charlie b:
Here it is: It doesn't matter.

I agree.

I should be more specific.

In the real world it may not matter.

On service calcs it does matter if you want to get the answer 'right' even though it will work either way.

 

[jeff43222]

Re: Is Residential Lighting Continuous?

Originally posted by iwire:
This came up so why not start a new thread about it?

Are residential lighting circuits continuous loads?

How many people actually wire dedicated lighting circuits in dwelling units?

I do. My thinking is that it's better to do it this way since it makes it extremely unlikely that an overload will cause the lights to go out. With no variable loads (i.e., receptacles) we can determine in advance what the maximum lighting load will be. Ever have a hair dryer overload the bathroom circuit and find yourself in a suddenly dark bathroom?

Continuous Load. A load where the maximum current is expected to continue for 3 hours or more.

I think a key word in there is "maximum" that says to me every light on the circuit would have to be expected to stay on for more than 3 hours at the same time.

I doubt I would say it is a continuous load.

Under those circumstances, I'd agree. But if you had a 15A lighting circuit where all lights on the circuit were controlled by the same switch(es), I'd limit the total load to 1440VA. I always assume lights are likely to be on for three or more hours at a time

 

[bphgravity]

Re: Is Residential Lighting Continuous?

I've never seen an exam question that included continuous loading for dwelling lighting. This includes exams from Experior, Promissor, and ICC. Nor have I ever read a reference book that put dwelling lighting into continuous loads. 99.99% of dwelling service calculations are already oversized using the standard method as it is now. More loads is the last we need to have added to dwellinf calculations.

 

[iwire]

Re: Is Residential Lighting Continuous?

Point taken Bryan and I agree 100% with your last sentence.

 

[petersonra]

Re: Is Residential Lighting Continuous?

IMO, residential lighting is not a continuous load. The exception (again IMO) is automatically controlled dusk-to-dawn type lighting.

Commercial or industrial lighting is since most people work at least 3 hours at a time.

I don't see any practical way to enforce such a ruling on residential lighting, nor is it really necessary to do so.

 

[jwelectric]

Re: Is Residential Lighting Continuous?

Weather or not lighting for the residential calculations are continuous or not would depend on weather they are turned on or off.

Now I did install some eight foot florescent fixtures in a basement one time and these were continuous end to end down one side of the basement.

Does this count?

 

[Mega VAR]

Re: Is Residential Lighting Continuous?

Why is this an issue.Itis calculated at a non continuous load.If it becomes a continuous load,so what..

 

[james wuebker]

Re: Is Residential Lighting Continuous?

Just remember in todays houses they are installing more and more can lights per household. The last house I did had 16 outside cans in the front and 14 on the sides and back. We also have to base the wattage off the fixture and not the bulb install. This person wanted them on a timer form 9pm til 4am. So is this a continuous load. I would have to say so. Also just think about all the can lights in the house. I bet he had over 50 in the house. My point is that the old days of putting in a 60 watt bulb is gone and putting in 100 watt can light fixtures are in. Just something to think about.
Jim

 

[charlie b]

Re: Is Residential Lighting Continuous?

Let's take a look at that word, "Maximum."

For the purpose of discussion, let's use, as an example, a 20 amp branch circuit, with 12 light fixtures connected, and with each fixture being rated at 100 watts.
</font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Does "maximum" mean the circuit's rating? In our example, is the "maximum" for this 20 amp branch circuit 20 amps?</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Does "maximum" mean the total connected load? In our example, is the "maximum" 10 amps?</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Does "maximum" mean the peak load, as measured during a reasonably representative time period, such as during a 30 day period? In our example, suppose we installed a data recorder and took measurements every 15 minutes for 30 days. Suppose the highest recorded current was 8 amps. So can we say that the "maximum" is 8 amps? If so, can we make a prediction at the design stage, as opposed to taking measurements after the home is built, and base our design on that prediction?</font>

<font size="2" face="Verdana, Helvetica, sans-serif">

 

[69boss302]

Re: Is Residential Lighting Continuous?

Who let charlie b get close to the dictionary again

 

[LarryFine]

Re: Is Residential Lighting Continuous?

Originally posted by iwire:
How many people actually wire dedicated lighting circuits in dwelling units?

I do, Like Jeff, and for similar reasons.

For example, I'll wire the typical 3-bedroom sleeping area with a 15a circuit for ceiling, closet, bath, hallway, etc. lighting; and a 20a circuit for receptacles in the same areas.

Unlike past generations, bedroom receptacle circuits aren't really lighting circuits anymore. Bedrooms have more TV's, computers, portable heaters, and such than the rest of the average house.

Plus, hair dryers, clothes irons, and other appliances are used in bedrooms more and more. By running separate circuits for lighting and receptacles, dimming from inrush current is minmized when TV's and other irems are turned on.

Let's not forget that, for those of us still under the '99 NEC (only bedroom receptacle outlets need be AFCI-protected, not all outlets) that this also reduces job cost a bit.

I also tend to do the same for other sections of the house; formal living rooms are probably the exception to the "receptacles aren't just for lighting anymore" notion, while dining rooms are often the opposite.

Originally posted by charlie b:
[QB] Let's take a look at that word, "Maximum."[qb]

"Let's take a look at that word, "Redneck." - Wild Wild West

[ September 08, 2005, 05:22 PM: Message edited by: LarryFine ]

 

[luckyshadow]

Re: Is Residential Lighting Continuous?

I know in my house when the girls were younger my lights would qualify as a continuous load. They were ALWAYS on ! I even made up a name for their "illness"; I call it Light Switch Disease.
The symptoms are: when you turn on a light you some how forget how to turn it off ! The good news is It IS curable ! Now the girls turn off lights but I can't get My wife to turn off a ceiling fan . I swear I have some ceiling fans that have been running for 9 years so far !

 

[charlie b]

Re: Is Residential Lighting Continuous?

Originally posted by luckyshadow:I swear I have some ceiling fans that have been running for 9 years so far!

But at least you don't have to worry about them being "continuous loads." There is already a 125% factor built into a load calculation for motors.

 

[apauling]

Re: Is Residential Lighting Continuous?

I came into contracting from the end rather than from the beginning; I am trying to stay away from puns here. I was always doing remodels and was always running into near maxed out circuits. I was always grateful for add room where I could tap onto an existing circuit. Because of this and other considerations, I always left circuits lightly loaded, if I could.

I liked splitting circuits between rooms so that a problem with a circuit would not leave a room with no power, and almost everyone else was doing the opposite. I also didn't like having all the lighting in one area on a single circuit (with afci this is probably more common now, but not putting hall lighting on same circuit as bedrooms, for example).

I also liked to split circuits in the kitchen so that items in one counter space had access to more than one circuit.

But I guess that is why my bids were just a bit too high and I never made a ton of money, like some around here.

In other words, I treated all circuits in residences as continuous loads.

paul