dEDICATED 15 amp bREAKER FOR Projector

Most recommend a dedicated 20 amp circuit for the projector, sub, and AV equipment. Some will do a dedicated circuit for each (three 20 amp circuits), I am doing one 20 amp circuit for the the three.

There is also some thought that a UPS makes good sense for the projector circuit if your area is subject to frequent power outages.

Having a UPS allows you to turn the system off and cool the bullb with the fan. Whether it's worth the effort is probably open to debate. For $99 Costco had this in stock a while back.

http://www.tripplite.com/products/pr...productID=3082

A single 20 amp circuit for all of your equipment is one of the easiest ways to avoid the dreaded ground loop. I will use a single outlet for my projector (end of run), a quad for the equipment room, then branch to sub locations (all off a 20 amp run). The equipment in the room will be plugged into a Furman power conditioner/surge protector ; I've seen a million dollars worth of gear get fried - it ain't pretty.
Also, several power units come equipped with isolated AC adapter outlets; that is a great feature.

For my lighting set up, I'll run two or more 15 amp circuits.

I 2nd Winkelmann

I ran 2 x 20Amp circuits into the equip room (both on same phase). I'm only using one at the moment. I then ran 20A romex from the equip closet to the PJ and sub positions.

I did this as I wanted power to PJ and Sub recepticles to run via a Power Conditioner / UPS to prolong lifetime of the PJ bulb. Some of the options on using inlets that were suggested were expensive so I've did the following:

APC J10--> 20A cord --> junction box with twist connections --> 20A Romex --> Recepticle --> PJ (or Sub)

In the Junction box I used double gang blank plate and drilled two holes. I found some cable glands (similar to this) at Home Depot that attached to the plate. I got a couple heavy duty power cords and cut the socket end of and passed thru the cable glands, secured and then used wire nuts to attach to the romex.

Here is a pic.



Whether you plan on using any type of conditioner/UPS now or in the future and help avoid ground loops make sure the PJ & Sub wiring routes via the equipment location.

Some see Conditioners/UPS as waste of money, maybe they are but helps me sleep a little better during stormy waether

Just my 2c

Cheers,
Mark

Mark,
Has you set-up passes inspection yet? It may be perfectly up to code, but I can just see an inspector scratching his head when he looks at it.

Not yet.

Way I see it is if they don't like it I'll patch it into the main 20A circuit then switch back when is passed. I can't see why it won't pass - but you never know.

I've actually run 4 circuits off the same phase for the HT equipment. (2) 20A dedicated lines for the subs, (1) 15A for the projector (with a separate switch to keep the kids from screwing with it when I'm not around) and (1) 20A for the equipment rack. All of my dimmer-connected lighting and other 'noisy' circuits are on the other phase.

Keep in mind that powerful subs (say, 1000W) can pull a pretty good bit of current. Add up two subs and a good-sized receiver, and you're pushing a single 15A circuit over it's limit. I like having separate Romex runs for them to keep from having sags during loud events. The good news with this approach is that ff you find a ground loop even though they are on the same phase (unlikely), there are several ways to fix it - some even meet code! Since you're not having to deal with other devices on the same circuit, you can do almost anything you want without worrying about causing safety problems or weird interaction elsewhere.

[quote=MauneyM]

"Keep in mind that powerful subs (say, 1000W) can pull a pretty good bit of current. Add up two subs and a good-sized receiver, and you're pushing a single 15A circuit over it's limit."

Remember, unlike a lighting circuit, most amps are rarely (if ever) driven to their full power.

Are those who run 20 amp circuits putting 20 amp or 15 amp receptacles on the outlets?

You should put 20a outlets.

If you want to go a step further, use Hubbell or Wattgate outlets cha-ching.

For arguments sake, is there AV equipment/projectors out there that require a 20 amp outlet (you know, with the funny looking plug)? In my limited experience, all the AV equipment I have seen and owned just used 15 amp outlets.

Continuous power, yes. However, subs can pull a tremendous amount of peak power - paticularly in action movies with explosions, and other LF effects. If the power distribution can't deliver the current, you get voltage sags, which can cause the response of the sub to be non-linear.

12-ga wire and a 20A breaker is a cheap improvement.

The method that Mark (BritInVA) is using for running a circuit between the power conditioner and the projector is exactly how my electrician stated he would do it. He said he would tie a power cord into romex using wire nuts etc. If that is how he would do it (and he has wired other HTs) I would assume it would pass inspection, at least here in Madison, WI.

No. The 20a outlets look exactly like standard 15a. They're built to take the extra power. Go to Home Depot or Lowe's and go to the elec section and you'll see both types on display.

20 Amp outlets have a "T" shaped slot.
20 Amp plugs have a prong that fits into 20 Amp outlets but not into 15 Amp outlets!

That is my understanding also. So back to my question, is there AV equipment/projectors out there that requires a 20 amp outlet? If not, then a 15 amp receptacle on a 20 amp circuit should accomplish the same. I am being the devils advocate here, just to make sure my logic (or lack there of) is not skewed.

Isn't 20a overkill? Why wouldn't 15a be sufficient? If you know all the devices that will be set on the circuit you could calculate the # of amps required.

Lets say you have a 1000 watt sub... amps = watts/volts, so... 1000/120 = 8.3 amps.

Just because individual components don't have 20A plugs does not mean the sum of all individual components won't require a draw of 16A.

For the cost involved and the peace of mind that some day down the line you may have so many goodies that absorb more than 12A and then you have to rip up your walls.

1) Your 'calculation' is overly simplistic and wrongly assumes two things. First, that the power supply and amp are 100% efficient - they never are. Second, that the device is running at unity power factor, which is only true for a purely resistive load.

2) Ever heard of inrush current?

3) It's about the wire gauge, not the breaker rating. Larger wire => less losses => less voltage sag under peak loading. To run 12 ga wire, code requires the use of a 20A breaker.

Also, general practice is to never plan to exceed 80% of the breaker rating on a circuit. Thus, a 15A circuit should never be expected to use more than 12A, and a 20A circuit should only be planned for 16A.

If you under calculate your breakers and crowd the circuit - the wire can heat up and trip the breaker. This usually occurs when too many amps kick in at one time and is the reason (in my area) why code requires multiple circuits in the kitchen.

MauneyM's point (3) is very important. Should you have more questions hire an experienced professional.

No one has convinced me that you need 20 amp receptacles yet I will not argue the need for 12 gauge wire and 20 amp circuit breaker, but if all equipment has 15 amp plugs, why is a 20 amp receptacle necessary?

Using the kitchen analogy, most receptacles down stream from a GFCI are 15 amp receptacles (on a 20 amp, 12 gauge circuit).

BTW, I have already bought 20 amp receptacles for my HT, I am just not sure why they would be necessary.

It depends on your local code whether or not it is legal, but:

Keep in mind, that your circuit protection is set for 20A. If you have a local device fault generating 18A connected to a 15A receptacle, it is conceivable that the receptacle could fail and start a fire without the breaker ever tripping to stop the fault.

The process of ensuring that all devices in the distribution chain are capable of handling whatever current they might have to handle is called 'protection coordination'.

Summary: Even if code allows you to use a 15A outlet on a 12ga/20A circuit, it's not necessarily a good idea. Using a 20A outlet won't cause any problems, and it might avoid serious trouble.

Gonzo,
Ever notice how the lights dim on a 15 amp circuit when you kick on the 15 amp circular saw? Try the same thing with a 20 amp circuit. All things equal, the dim down will be less noticeable.

Now, how would a 250 - 450 dollar projector bulb take an unclean or low power supply? A shorter life.

Just for the record:

A 15A duplex outlet on a 20A breaker (with 12ga wire) is perfectly acceptable, and up to code. However, there are a lot of crappy 15A outlets out there while I've never seen any poor quality 20A outlets. If you use decent quality 15A outlets, you'll be fine.

As for Mark's installation, I have no idea if that will pass or not.

Jim

I see your point, but am not arguing the need for a 20amp circuit and 12 gauge wire. I agree with that. It is my understanding (and maybe incorrect) that there is no difference between a 15 amp and 20 amp receptacle except for the fact that a 20 amp receptacle has a different shape socket that allows a 20 amp OR a 15 amp plug to fit into it. On the other hand, you can not fit a 20 amp device into a 15 amp receptacle because of the different shape of the 20 amp plug. The 15 amp receptacle serves as the "gate keeper" for the circuit, by not allowing a device (20 amp) that will draw too much current.

Now, MauneyM is saying that the receptacles are innately different beyond the difference of the socket (eg, different internal workings of the receptacle, a larger gauge conductor within the the receptacle). If true, that answers my question. However, why would it ever be acceptable (which it is in my town), code wise, to have a 15 amp receptacle on a 20 amp circuit, if it could lead to a receptacle melt down?

Once again, I am not trying to be difficult. Just curious.

Even a single duplex (two outlets) on a 20A circuit is OK. A single outlet (like for a sump pump) on a 20A circuit is not up to code. But again, quality matters. Don't buy junk for an important dedicated outlet for your projector and other equipment.

Jim

Note: This is not OK for StoneMason, who lives in Canada. They have different code rules.

Here's the deal: A 15A outlet only has to be tested and UL listed for 15A. A 20A outlet has to be tested and UL listed for 20A. Now, as BuffaloJim said, many 15A outlets use the same quality and thickness of material (and contact pressure, etc)as their 20A cousins - no issue if you're using one of these. Be careful, though, as some of the low-end home center stuff is pretty junky.

Bottom line: use good stuff, and build for more than you plan to use. The cost difference is miniscule, and you will probably be glad you did.

That's the best advice you can give! That's why I'm going to run a number of 20A circuits to the eqpt room. And it would explain why we have 2 network connections in every room... even the kitchen... but not the bathroms.

Overkill is the name of the game!