Electric wiring help.

[Sean]

Hey Could someone with a little electric wiring experience double check this for me.

I am installing track lighting for a friend. I am going to put up about 55 feet. It will be wired with 12/2 on a 20A cuircut. He wants to hang 10-50 watt halogens. Here is my math:

Existing:
Chandelier 10*60 watts=600
Florescents 4*136 watts *1.25=680

Adding:
Track Lights 10*50 watts *1.25=625
Total 1905 watts

20A*120*80%=1920

That is close but it should be fine unless there is something I need to add because the track is rather long.

Thanks for any thoughts.

 

[Inodoro_Pereyra]

Sorry, I had replied before checking your math, and I was mistaken. To have a more appropriate safety margin, you should have used 70% instead of 80% in your last equation. That would've called for about 22A, or, to make it a little easier:

1905/120*1.42=22.5425A

That said, having a 20A circuit is kinda too close. It'd work, but I'd rather use #10 wire and a 30A breaker.

 

[Hammy71]

Yeah, it's a little close, but should be fine. And, by the NEC it's 80% of the wire/breaker capacity.

 

[Inodoro_Pereyra]

Yeah, I know the NEC calls for 80%. That's why I don't like it.

 

[Sean]

thanks,

I don't want to mess with the breaker, or the wire comming from it to the box in the ceiling. I think I am going to get him to change the chandalier to a fixture with fewer bulbs, or maybe just one. I don't like it right on the edge. You never know when someone will stick a few more fixtures on the track.

There is no additional margin for the 55 feet of track?

 

[Inodoro_Pereyra]

What do you mean?
For what you posted, the track's consumption is included in your 1905W total...

You also have to consider if they will use all the lighting together, and for how long. The #12 wire will work for 25A @ 90*C, so it's not like you're that tight on the wiring. Either way, if you can get them to use fewer lights, even better.

 

[kjung]

My biggest concern is what else is on the circuit? Also, keep in mind that code is the LEAST ACCEPTABLE limit.

How big of a room is it that you need 10 50w halogen lights???

 

[Sean]

What do you mean?
For what you posted, the track's consumption is included in your 1905W total...

The halogen lights are included in the 1905W. My question is whether there is a reason to reduce the max power on the circuit because of the length of the track.

I am not an electrician so I don't know the code or standard working practice. The box is there, I am only wiring from the box to the track.

My biggest concern is what else is on the circuit? Also, keep in mind that code is the LEAST ACCEPTABLE limit.

How big of a room is it that you need 10 50w halogen lights???

Yea, Least acceptable, that is why I think the Chandelier has to go. The only things on that branch are what I listed, no outlets, nothing else.

The room is about 24 feet long and wide, the ceiling is 10 feet. It's a big room. The halogens will be spots on artwork hung on the walls.

 

[Hammy71]

The halogen lights are included in the 1905W. My question is whether there is a reason to reduce the max power on the circuit because of the length of the track.

I am not an electrician so I don't know the code or standard working practice. The box is there, I am only wiring from the box to the track.



Yea, Least acceptable, that is why I think the Chandelier has to go. The only things on that branch are what I listed, no outlets, nothing else.

The room is about 24 feet long and wide, the ceiling is 10 feet. It's a big room. The halogens will be spots on artwork hung on the walls.

50' won't make that much of a difference. As long as he/you don't add anymore lights. Which....it really easy to do. Just make sure he knows that he can't add anything else. I don't have a problem with the NEC. It's what I had to study and use to get my Master's license. It's already giving you a 20% margin. But, there are calculations for tracklighting. They use the length of the track because, as I mentioned, it's really easy to add a crap load of lights.

 

[Sean]

Thanks all for the reassurance.

 

[mdfriday]

Hey Could someone with a little electric wiring experience double check this for me.

I am installing track lighting for a friend. I am going to put up about 55 feet. It will be wired with 12/2 on a 20A cuircut. He wants to hang 10-50 watt halogens. Here is my math:

Existing:
Chandelier 10*60 watts=600
Florescents 4*136 watts *1.25=680

Adding:
Track Lights 10*50 watts *1.25=625
Total 1905 watts

20A*120*80%=1920

That is close but it should be fine unless there is something I need to add because the track is rather long.

Thanks for any thoughts.

You do not need to multiply the lighting load by 125%.

You are fine at the stated loads as long as there are no other loads or receptacles on that 20A circuit.

Yes, you can only load the breaker to 80%.

 

[mdfriday]

What do you mean?
For what you posted, the track's consumption is included in your 1905W total...

You also have to consider if they will use all the lighting together, and for how long. The #12 wire will work for 25A @ 90*C, so it's not like you're that tight on the wiring. Either way, if you can get them to use fewer lights, even better.

True, about the #12 for 25A, but you still cannot put it on a breaker larger than 20A.

 

[Inodoro_Pereyra]

I agree with Hammy's las post (well, all except not having a problem with NEC, but that has already been covered). That's why I still think it'd be much better to either replace the wiring and breaker, or to split the load between 2 circuits. In my experience, you can tell people not to add anything until you're blue on the face, but, as years go by, they tend to forget anyway.

What do you mean?
For what you posted, the track's consumption is included in your 1905W total...

You also have to consider if they will use all the lighting together, and for how long. The #12 wire will work for 25A @ 90*C, so it's not like you're that tight on the wiring. Either way, if you can get them to use fewer lights, even better.

True, about the #12 for 25A, but you still cannot put it on a breaker larger than 20A.

Sure you can. You can put a 100A breaker, if you want. It's not advisable, just as it is not advisable to put a 1900W load on a 20A circuit (especially when you have fluorescent lighting, that normally has a power conversion factor (cos&#966 of about 0.8-0.9) (that, Sean, means that fluorescent light consume more than stated), but it's not like the "power police" is gonna come knocking at your door if you do.

 

[mdfriday]

I agree with Hammy's las post (well, all except not having a problem with NEC, but that has already been covered). That's why I still think it'd be much better to either replace the wiring and breaker, or to split the load between 2 circuits. In my experience, you can tell people not to add anything until you're blue on the face, but, as years go by, they tend to forget anyway.





Sure you can. You can put a 100A breaker, if you want. It's not advisable, just as it is not advisable to put a 1900W load on a 20A circuit (especially when you have fluorescent lighting, that normally has a power conversion factor (cos&#966 of about 0.8-0.9) (that, Sean, means that fluorescent light consume more than stated), but it's not like the "power police" is gonna come knocking at your door if you do.

My responses were based on CODE. Not what anyone with a screw driver could acomplish.

AND NO, you cannot feed a lighting circuit with a 100A breaker, check your code book. #12 is limited to 20A, again, check your code book.

I don't only come on a forum and play electrical contractor, it is my day job as well.

 

[Bernie Brewer]

My responses were based on CODE. Not what anyone with a screw driver could acomplish.

AND NO, you cannot feed a lighting circuit with a 100A breaker, check your code book. #12 is limited to 20A, again, check your code book.

I don't only come on a forum and play electrical contractor, it is my day job as well.

It is my day job, too. For some reason he thinks that if you are not doing electrical for a living you don't have to follow code. We went round and round about this with him in another thread. Save your breath, he won't listen.

 

[Inodoro_Pereyra]

I agree with Hammy's las post (well, all except not having a problem with NEC, but that has already been covered). That's why I still think it'd be much better to either replace the wiring and breaker, or to split the load between 2 circuits. In my experience, you can tell people not to add anything until you're blue on the face, but, as years go by, they tend to forget anyway.

Sure you can. You can put a 100A breaker, if you want. It's not advisable, just as it is not advisable to put a 1900W load on a 20A circuit (especially when you have fluorescent lighting, that normally has a power conversion factor (cos&#966 of about 0.8-0.9) (that, Sean, means that fluorescent light consume more than stated), but it's not like the "power police" is gonna come knocking at your door if you do.

My responses were based on CODE. Not what anyone with a screw driver could acomplish.

AND NO, you cannot feed a lighting circuit with a 100A breaker, check your code book. #12 is limited to 20A, again, check your code book.

I don't only come on a forum and play electrical contractor, it is my day job as well.

Sure they are. Funny how you chose to reply only to what was convenient to you, though.
There's a difference between what you CAN do, and what you SHOULD do. Sure it's dumb. Just as dumb as staying with undersized wiring just to save a few bucks and a couple of hours of work.
And, just in case you didn't notice (being that you seem to only notice what suits you), I've been suggesting from the beginning to use thicker wire and a bigger breaker. Contrarily to what you (and other people here) may think, I too do things by code. The difference is I follow DIN code, which is a lot more demanding (and a lot safer) than NEC.

 

[EarthBound]

My responses were based on CODE. Not what anyone with a screw driver could acomplish.

AND NO, you cannot feed a lighting circuit with a 100A breaker, check your code book. #12 is limited to 20A, again, check your code book.

I don't only come on a forum and play electrical contractor, it is my day job as well.

It is my day job, too. For some reason he thinks that if you are not doing electrical for a living you don't have to follow code. We went round and round about this with him in another thread. Save your breath, he won't listen.

+1 to both of these comments. It is my job, as EE of a power plant in America, to make sure that all electrical devices follow NEC code, not DIN. If I was unemployed (a result of getting fired for being a bad electrician, maybe?) and never brewed beer, I would not troll all the electrical threads on HBT, spreading bad advice. It's gonna get someone killed.

When everyone on here is pointing out that you are wrong, you might want to listen! Like the old saying goes, "The first time someone calls you a horse you punch him in the nose, the second time someone calls you a horse you call him a jerk, but the third time someone calls you a horse, well then perhaps it's time to go shopping for a saddle."

 

[Inodoro_Pereyra]

If I was unemployed (a result of getting fired for being a bad electrician, maybe?) and never brewed beer, I would not troll all the electrical threads on HBT, spreading bad advice. It's gonna get someone killed.

That right there speaks volumes about you as a human being, and as an engineer.
First, you don't have a clue why I'm unemployed. But then again, seems you love to talk on things you know noting about.
Second, I fail to see how brewing has anything to do with knowing electricity. Maybe you can explain that.
Third, and most important, maybe you could also explain how recommending to switch to #10 wire and a 30A breaker is "bad advise", and how is it more likely to "get someone killed" than staying with an undersized wire and breaker.