I'm installing 8 of these Metaluz fixtures (T-8 bulbs)

http://www.google.com/products/catal...=0CIIBEPICMAU#

in the shop. Can I put them all on one 15 amp breaker without
problems?

Thanks.
Sonny

On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)

http://www.google.com/products/catal...=0CIIBEPICMAU#

in the shop. Can I put them all on one 15 amp breaker without
problems?

Thanks.
Sonny

I can run a 1500 watt space heater on a 15 amp circuit. You are in the
neighborhood of using 1024 watts. You should be fine. But keep that in
mind if you are sharing that circuit with other power tools.

On Feb 4, 7:08*pm, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)

http://www.google.com/products/catal...397US398&q=met....

in the shop. *Can I put them all on one 15 amp breaker without
problems?

Thanks.
Sonny

I use 20 amp breakers in my basement, so maybe no applicable. I have
18 and 19 fluorescent fixtures on two different circuits. Each
fixture is two 4 foot T12 bulbs. 40 watts I think. You will have 32
bulbs on 15 amp breaker. I have 38 bulbs on 20 amp breaker.

On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
....
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

The fixtures should run about 32 Watts for each bulb plus the ballasts.
Depending whether you select the three or four bulb fixtures they will
run about 120 to 160 Watts each fixture. Eight fixtures will be handled
OK on on 15 Amp circuit breaker but you may want to split them up with
some thinking about lighting scenarios.

E.g. Suppose something shorts out in a bulb or fixture and you are in
the middle of a TS cut of a sheet of plywood and **ALL** your shop
lights go out at the same time but your saw doesn't? The same thing
applies to another person that enters and shuts off the light switch,
without thinking they are already on, or to call you for supper?

-------------

"Sonny" wrote in message
...

I'm installing 8 of these Metaluz fixtures (T-8 bulbs)

http://www.google.com/products/catal...=0CIIBEPICMAU#

in the shop. Can I put them all on one 15 amp breaker without
problems?

Thanks.
Sonny

On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would
only put about 7.5 amps.

On 2/7/2012 10:01 AM, Keith Nuttle wrote:
On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would only
put about 7.5 amps.


Why would you calculate in a safety factor under a 15 amp breaker?
shouldn't the circuit breaker be the safety factor?

On 2/7/2012 9:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

Excellent point. I have 16, 4' T8's and 2 screw in florescent bulbs on
one switch/circuit and don't have a need to turn any off or on with out
the others but if a breaker tripped they would all go out.

BUT I have a garage door opener on a separate circuit that turns on a
light when it senses temperature movement. Last summer I worked with
the garage door open so lighting was not a safety factor but the garage
door sensor could not see me at all when the temp in the garage was
above 100 degrees. I became the cold spot. LOL

On 2/7/2012 9:41 AM, Leon wrote:
On 2/7/2012 10:01 AM, Keith Nuttle wrote:
On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would only
put about 7.5 amps.


Why would you calculate in a safety factor under a 15 amp breaker?
shouldn't the circuit breaker be the safety factor?

the safety factor is that breakers aren't supposed to be used more than
80% of their rating.

On 2/7/2012 11:19 AM, chaniarts wrote:
....


Why would you calculate in a safety factor under a 15 amp breaker?
shouldn't the circuit breaker be the safety factor?

the safety factor is that breakers aren't supposed to be used more than
80% of their rating.

That's for continuous loads.

If, of course, the probability is that the shop will be occupied
regularly for 3 hr at a time, that would be a continuous load.

Assuming they're 32W bulbs (I think that's right w/o checking?) it would
be 32*8*4/120 = 8.5 A. That's well under .8*15 = 12. Well, ok, even
40W/tube is still only 10+ A. Either way, it's ok by load rating but it
still is probably not so smart from the logistics mentioned earlier
unless there are other lighting circuits that aren't being disabled and
will be in use at the same time.

--

On 2/7/2012 11:41 AM, Leon wrote:
On 2/7/2012 10:01 AM, Keith Nuttle wrote:
On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would only
put about 7.5 amps.


Why would you calculate in a safety factor under a 15 amp breaker?
shouldn't the circuit breaker be the safety factor?

With the 50% factor, that gives me the room to make mistakes on the
installation and gives me a larger comfort zone.

In the future when I decide to add something to that circuits there will
be room. ie another light in an area I did not realize would be in the
shadow, under a cabinet, etc.

Thanks all. I think I have all my bases covered. 5 of the fixtures
are installed and all 8 will be on one circuit. No other items on the
circuit. Much improved lighting, as the new lights are placed in
better positions than the old temporary ones. One old 8' fixture have
been installed in the garage area, which also has a new 8' fixture.
Those lights and 2 outside motion lights are on a seperate circuit. I
want to add at least 1 more 8' fixture to the garage area. One old 8'
fixture is now under a 12' span of upper cabinets and plugs into a
socket, only when needed.

I'm in south Louisiana and, though the shop has no heat, I rarely work
when it's cold, and it's rarely too cold to work. The shop's main
work area is usually wide open when I'm there. It has 2 sets of
double doors to the outside (back) and one single doorway (no door) to
the garage. There is open space to 2 other "rooms" with windows, so
daylight comes into those rooms, also. The main work area has 3 sets
of double windows, as well, though one set is boarded up, at the
moment (old sashes not cleaned, repainted and installed, yet). If the
lights go out, there is plenty of daylight coming in from all
directions.

I don't use the garage as a garage, though that area was originally a
garage for the house (now my shop). I use the garage area for some
storage and for the jointer, planer, anvil, pedestal grinder and a
cabinet/bench sharpening station. The garage area has drive through
doorways, front and back, and a 4' X 9' window on the outside wall....
lots of daylight coming into the garage area, also.

The shop is finally becoming more comfortable to work in and things
are better placed for convenient working. I've been remodeling the
place for a few years. It's been slow going, but it's getting there.
For the past year and a half, the city has been concreting the coulee
(stream) near the shop, preventing me from accessing the exterior
(including windows) for remodeling. Their work right-of-way abutts
the shop, so that side lawn was fenced off. They have nearly
finished, so I'm trying to get things organized for that side of the
shop's remodeling.

Thanks again.
Sonny

On Feb 4, 8:08*pm, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)

http://www.google.com/products/catal...397US398&q=met....

in the shop. *Can I put them all on one 15 amp breaker without
problems?

Thanks.
Sonny

Look at the ballast cases. If they're plastic, about half
of them will fail within 2 weeks due to them not being
able to radiate heat, so you should have no problem
with the breaker overloading.

On 2/7/2012 11:19 AM, chaniarts wrote:
On 2/7/2012 9:41 AM, Leon wrote:
On 2/7/2012 10:01 AM, Keith Nuttle wrote:
On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does
trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it
would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would only
put about 7.5 amps.


Why would you calculate in a safety factor under a 15 amp breaker?
shouldn't the circuit breaker be the safety factor?

the safety factor is that breakers aren't supposed to be used more than
80% of their rating.

I understand that you don't want breakers tripping and apparently
according to what I have been told modern breakers may trip at 80%.
What is up with that? But a 50% safety factor seems a bit extreme/over
kill.

On 2/7/2012 3:36 PM, Keith Nuttle wrote:
On 2/7/2012 11:41 AM, Leon wrote:
On 2/7/2012 10:01 AM, Keith Nuttle wrote:
On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does
trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it
would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would only
put about 7.5 amps.


Why would you calculate in a safety factor under a 15 amp breaker?
shouldn't the circuit breaker be the safety factor?

With the 50% factor, that gives me the room to make mistakes on the
installation and gives me a larger comfort zone.

Like load miscalculation mistakes?

In the future when I decide to add something to that circuits there will
be room. ie another light in an area I did not realize would be in the
shadow, under a cabinet, etc.

Ok, you are working with the assumption that this will not always only
be a dedicated circuit for this amount of load.

On 2/8/2012 7:26 AM, Leon wrote:
....

I understand that you don't want breakers tripping and apparently
according to what I have been told modern breakers may trip at 80%. What
is up with that? But a 50% safety factor seems a bit extreme/over kill.

No, breakers are designed and tested (in open air) to carry 110% of
rated current indefinitely. Breaker test curves are available; typical
trip times are sotoo 150% - 1 minute, 200% - 20 sec. and 300% - 5 sec.,
long enough for motor-start current, etc., w/o tripping.

The 80% load rule is part of the NEC Code specifications and is a
derating for continuous loads to account for the fact that in use
breakers are not in free air but installed in cabinets and so operate at
a higher temperature than would under the UL test conditions.

Certainly if an individual chooses to use even more conservative
derating that's their prerogative and that is, of course, still in
compliance w/ Code but there's no real reason for it other than choice
to do so as that poster said, for future expansion, say.

--

On 2/7/2012 3:40 PM, Sonny wrote:
Thanks all. I think I have all my bases covered. 5 of the fixtures
are installed and all 8 will be on one circuit. No other items on the
circuit. Much improved lighting, as the new lights are placed in
better positions than the old temporary ones. One old 8' fixture have
been installed in the garage area, which also has a new 8' fixture.
Those lights and 2 outside motion lights are on a seperate circuit. I
want to add at least 1 more 8' fixture to the garage area. One old 8'
fixture is now under a 12' span of upper cabinets and plugs into a
socket, only when needed.
....

... The garage area has drive through
doorways, front and back, and a 4' X 9' window on the outside wall....
lots of daylight coming into the garage area, also.

....

As long as there is either other light on when dark (or you _never_ work
after dark), sounds fine. The concern is obviously as others noted that
in the unlikely case that the lighting circuit were to trip while in
process of some tricky operation. Altho unlikely, still the
consequences could obviously be serious if it were to go dark.

--

On Tue, 07 Feb 2012 11:01:31 -0500, Keith Nuttle
wrote:

On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

No, only if the load is purely resistive. Fluorescents aren't.

watts = volts * amps * power_factor

so: watts/(volts*power_factor) = amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would
only put about 7.5 amps.

Given your 900W lights, and a power factor of .5 (probably too low for even
old fluorescents) you'd have 15A flowing in the circuit. A PF of .7 wouldn't
be a low guess, though. The point being that you can't ignore the power
factor.

On 2/8/2012 10:21 PM, zzzzzzzzzz wrote:
On Tue, 07 Feb 2012 11:01:31 -0500, Keith
wrote:

On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. Whether you should depends on whether these are going to
then be the only lighting circuit in the area (assuming you're not also
running another series of receptacles and/or lights as well off the
circuit).

If there's other lighting that will be on in case the circuit does trip,
then you're ok but if there's only the one lighting circuit in the area
it would be far better to split them--and, in all likelihood it would be
better anyway simply to have some level of control.

--

This should be a mathematical calculations.

Watts / Volts = Amps

No, only if the load is purely resistive. Fluorescents aren't.

watts = volts * amps * power_factor

so: watts/(volts*power_factor) = amps

Calculate the amps used for each bulb on the circuit, add them together.
The total amps used should be less that the breaker minus a safety
factor. I like to use a 50% factor, so on a 15 amp circuit I would
only put about 7.5 amps.

Given your 900W lights, and a power factor of .5 (probably too low for even
old fluorescents) you'd have 15A flowing in the circuit. A PF of .7 wouldn't
be a low guess, though. The point being that you can't ignore the power
factor.

As I said in a follow up to my post about mathematical calculation

"With the 50% factor, that gives me the room to make mistakes on the
installation and gives me a larger comfort zone. "

On 2/8/2012 9:21 PM, zzzzzzzzzz wrote:
On Tue, 07 Feb 2012 11:01:31 -0500, Keith
wrote:

On 2/7/2012 10:46 AM, dpb wrote:
On 2/4/2012 7:08 PM, Sonny wrote:
I'm installing 8 of these Metaluz fixtures (T-8 bulbs)
...
in the shop. Can I put them all on one 15 amp breaker without
problems?


_CAN_, yes. ...
....
This should be a mathematical calculations.

Watts / Volts = Amps

No, only if the load is purely resistive. Fluorescents aren't.

....

Given your 900W lights, and a power factor of .5 (probably too low for even
old fluorescents) you'd have 15A flowing in the circuit. A PF of .7 wouldn't
be a low guess, though. The point being that you can't ignore the power
factor.

That's so for a single (uncorrected) fluorescent bulb/tube. Commercial
multi-tube fixtures invariably include PF correction and will have a PF
of 0.9 or greater for quality lighting, probably 0.8 even for any
inexpensive import.

I just looked at the Cooper catalog--THD (a related measure) is listed
as 10% for the fixture.

OP's just fine...

--

On 2/9/2012 8:05 AM, Keith Nuttle wrote:
....

As I said in a follow up to my post about mathematical calculation

"With the 50% factor, that gives me the room to make mistakes on the
installation and gives me a larger comfort zone. "

That's so, but still unnecessary and potentially expensive for a larger
installation. If taken to extremes, at some point it means larger
panel(s) than required as well as the additional wiring, labor, etc.,
etc., etc. Of course, if labor is free that can be discounted but the
other costs are real. For a single added circuit or two, sure, the
extra may be minimal.

As noted in the other followup, OP won't be in trouble; commercial
fluorescent fixtures are compensated for PF and so the wattage is close
enough to not need to worry about unless really pushing the limit.

It is an interesting point that afaik individual cfl bulbs are not being
compensated and if not as they become more prevalent certainly at least
some of the purported gains will be less than hoped for if the overall
PF were to drop measurably.

--

I have seen ones that state compensated to 0.91 and 0.89 PF. A small factor
but not that significant.

Circuits are only supposed to be designed to 80% of the protection, here,
anyway. That gives you 12 amperes on a breaker. I would split the lights
into useful groups on two circuits, if I was close, anyway. A few for
security lighting at nights for the cops (or yourself) to peer in?


---------
"dpb" wrote in message ...
As noted in the other followup, OP won't be in trouble; commercial
fluorescent fixtures are compensated for PF and so the wattage is close
enough to not need to worry about unless really pushing the limit.

It is an interesting point that afaik individual cfl bulbs are not being
compensated and if not as they become more prevalent certainly at least
some of the purported gains will be less than hoped for if the overall
PF were to drop measurably.

-------

On 2/9/2012 8:05 AM, Keith Nuttle wrote:
As I said in a follow up to my post about mathematical calculation

"With the 50% factor, that gives me the room to make mistakes on the
installation and gives me a larger comfort zone. "
-

On 2/10/2012 1:47 PM, Josepi wrote:
I have seen ones that state compensated to 0.91 and 0.89 PF. A small
factor but not that significant.

Circuits are only supposed to be designed to 80% of the protection,
here, anyway. That gives you 12 amperes on a breaker. I would split the
lights into useful groups on two circuits, if I was close, anyway. A few
for security lighting at nights for the cops (or yourself) to peer in?
....

Again, the 80% is for continuous circuits in NEC. A local reqm't beyond
NEC isn't unheard, of course.

The OP's loading is 10 A even counting a PF of 0.9 for the proposed
lighting and still 11 for 0.8. He's not even close to needing a second
circuit from a loading standpoint.

The topic of splitting for other reasons was also raised and OP says has
alternate backup for the safety issue and wasn't concerned about
switching so it's his call...there is no other Code reqm't in play to
require it.

--

Totally agree.

He'll be close, depending on the never stated, wasted, ballast power. Even
more so if he chooses 3 bulb units.

IIRC the electronic ballasts are OK with shorting the bulb count in the
fixtures. If he decided, after turning them on, to only put two bulbs or
three in selected fixtures where not as much lighting is needed he could
save some energy.

Of course Americans don't seem to be obsessed with energy saving crap as
many Canukistanis. In summer it can add heat to your shop to make it more
expensive. In winter? almost free.


------------
"dpb" wrote in message ...
Again, the 80% is for continuous circuits in NEC. A local reqm't beyond
NEC isn't unheard, of course.

The OP's loading is 10 A even counting a PF of 0.9 for the proposed
lighting and still 11 for 0.8. He's not even close to needing a second
circuit from a loading standpoint.

The topic of splitting for other reasons was also raised and OP says has
alternate backup for the safety issue and wasn't concerned about
switching so it's his call...there is no other Code reqm't in play to
require it.

--