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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Mark Olsen on July 15, 2015, 09:40:46 am

Title: Overseas Power Board
Post by: Mark Olsen on July 15, 2015, 09:40:46 am
OK .. so I am from Australia but I'm currently spending a couple of years here in the US.

I have bought a bunch of my sound gear over with me, that includes wireless receivers, recording interfaces, mac mini etc.
I have three racks that are powered by these ..

http://www.ji.com.au/products/RAC0600/

If I just replace the feeder IEC cable with a US version, am I good to go?
All the gear inside the racks is 100-240 V autoswitching, but obviously have Australian plugs.
If I have to change the power boards, I'm also up for about 15 new cables and 9 plug packs ..... :-(

I'm mostly worried about the increased amp requirements for the surge protector, although there is no high power gear in any of these racks.

If I have to swap these power boards out, can you suggest a good alternative?
I really like the recessed face on these boards, it keeps everything within the rack body.

Cheers

Mark
Title: Re: Overseas Power Board
Post by: Cailen Waddell on July 15, 2015, 10:49:00 am
If everything is auto switching I would think you would be good to go - BUT, only if this is all relatively low current draw gear.    The wire inside your powerboard is sized for a 240v feed, which might mean it doesn't have enough current carrying capacity when your gear is running at 120v and draws more current.   


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Title: Re: Overseas Power Board
Post by: Mike Sokol on July 15, 2015, 11:14:12 am
If everything is auto switching I would think you would be good to go - BUT, only if this is all relatively low current draw gear.    The wire inside your powerboard is sized for a 240v feed, which might mean it doesn't have enough current carrying capacity when your gear is running at 120v and draws more current.   

I would agree, as long as there are no heavy-duty power amplifiers in the rack. If this is all processing gear, that's not a lot of current draw and it's likely fine. You can always add up the listed amperage draw on the back of each piece of gear and make sure it's no more than 15 amps. Of course, if your distro in the rack has an 8 or 10-amp fuse you'll find out soon after plugging into 120-volt power. If it's more than 8 or 10 amperes, then the fuse will blow and you'll know you need to swap out the distro. If the 8 or 10-amp fuse holds fine, then all is well and you may proceed.

BTW: What are you doing here in the States and what kind of gigs do you have here? This particular forum takes a few swerves, so as long as we weave in a power story or two it's all good.  Oh yes, no bashing of Edison outlets like my UK buddies do (Not you, Steve). We know they're crap... but they're all we've got. ;)
Title: Re: Overseas Power Board
Post by: Mark Olsen on July 15, 2015, 11:37:26 am
I would agree, as long as there are no heavy-duty power amplifiers in the rack. If this is all processing gear, that's not a lot of current draw and it's likely fine. You can always add up the listed amperage draw on the back of each piece of gear and make sure it's no more than 15 amps. Of course, if your distro in the rack has an 8 or 10-amp fuse you'll find out soon after plugging into 120-volt power. If it's more than 8 or 10 amperes, then the fuse will blow and you'll know you need to swap out the distro. If the 8 or 10-amp fuse holds fine, then all is well and you may proceed.

BTW: What are you doing here in the States and what kind of gigs do you have here? This particular forum takes a few swerves, so as long as we weave in a power story or two it's all good.  Oh yes, no bashing of Edison outlets like my UK buddies do (Not you, Steve). We know they're crap... but they're all we've got. ;)

My day job is actually in the military, so that's why I'm here.  I just couldn't bear the idea of not bringing all my audio gear with me though, just in case ...

I actually don't really care one way or the other about the Edison plug, but I don't understand why none of your domestic power outlets have switches. It's always awesome seeing sparks fly when you plug things in that are already trying to draw current.

And then your higher amp stuff is just confusing as hell .. I'm used to just a 20A three phase plug and a 32A three phase plug. That's about the only variations you're ever likely to get on gigs .. from hotels to generators. Over here is seems that you just never know what you're going to get ...

Mark

Mark
Title: Re: Overseas Power Board
Post by: Scott Holtzman on July 15, 2015, 11:52:02 am


Quote from: Mark Olsen
Over here is seems that you just never know what you're going to get ...

Mark

Mark

Same with the women here


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Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 15, 2015, 12:58:48 pm
If everything is auto switching I would think you would be good to go - BUT, only if this is all relatively low current draw gear.    The wire inside your powerboard is sized for a 240v feed, which might mean it doesn't have enough current carrying capacity when your gear is running at 120v and draws more current.   

The referenced powerboard is rated for 10A. Note that current draw will be double at 120V versus 240V. If the equipment draws less than 5A a 240V, there should not be an issue. If it draws more than 5A at 240V, the equipment will need to be reconnected to additional powerboards.

Mark Olsen, note that our 120V circuits provide either 15A or 20A. Most 20A circuits are supplied with 15A receptacles: this means that while the 20A circuit itself can supply a total of 20A, each receptacle is limited by nameplate rating to 15A. A 20A 120V receptacle can be identified by the sideways T-shaped slot. (A 20A receptacle will accept either a 20A or a 15A plug.)

To put it another way, if you see a 15A receptacle, it could be a 15A or a 20A circuit. But if you see a 20A receptacle, there's a really high probability* that it's a 20A circuit.

* What do I mean by a really high probability? I mean that American's aren't as afraid of electricity as they should be, and have an "I can do it!" spirit, which means that the circuit may have been wired by someone not qualified to do so, which means that until you verify it and meter it, you can't assume anything when it comes to electrical wiring here.

EDIT: Added clarification that a 15A receptacle on a 20A circuit doesn't actually limit the current draw.
Title: Re: Overseas Power Board
Post by: Cailen Waddell on July 15, 2015, 02:00:12 pm
And now Jonathan has done some Maths for you.  Super. 


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Title: Re: Overseas Power Board
Post by: Mark Cadwallader on July 15, 2015, 02:55:03 pm
The referenced powerboard is rated for 10A. Note that current draw will be double at 120V versus 240V. If the equipment draws less than 5A a 240V, there should not be an issue. If it draws more than 5A at 240V, the equipment will need to be reconnected to additional powerboards.

Mark Olsen, note that our 120V circuits provide either 15A or 20A. Most 20A circuits are supplied with 15A receptacles: this means that while the 20A circuit itself can supply a total of 20A, each receptacle is limited to 15A. A 20A 120V receptacle can be identified by the sideways T-shaped slot. (A 20A receptacle will accept either a 20A or a 15A plug.)

To put it another way, if you see a 15A receptacle, it could be a 15A or a 20A circuit. But if you see a 20A receptacle, there's a really high probability* that it's a 20A circuit.

* What do I mean by a really high probability? I mean that American's aren't as afraid of electricity as they should be, and have an "I can do it!" spirit, which means that the circuit may have been wired by someone not qualified to do so, which means that until you verify it and meter it, you can't assume anything when it comes to electrical wiring here.

Not to confuse the OP, but I have a question. How does a NEMA 5-15R receptacle that is downstream of a 20A circuit breaker limit the current to 15A?  I know that a 5-15P is designed for equipment that is not rated for more than 15A, but how does the receptacle "know" (or care) the maximum current draw is to be limited to 15A?  Unless I've missed something, the innards of a 5-15C and a 5-20C are identical. Am I missing something?
Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 15, 2015, 03:25:23 pm
Not to confuse the OP, but I have a question. How does a NEMA 5-15R receptacle that is downstream of a 20A circuit breaker limit the current to 15A?  I know that a 5-15P is designed for equipment that is not rated for more than 15A, but how does the receptacle "know" (or care) the maximum current draw is to be limited to 15A?  Unless I've missed something, the innards of a 5-15C and a 5-20C are identical. Am I missing something?

That's the thing. It doesn't. A 15A duplex receptacle is rated for 20A feed-through (to permanently wired downstream devices) when connected using the terminal screws (generally not when using the "backstab" connections). It is only rated at 15A through each of the face connections. A device with a 15A plug is not supposed to draw more than 15A -- most USA outlet strips will have built-in overcurrent protection equal to or less than 15A. However, most plug-in splitters (the kind with no cord, just prongs on the back) have NO overcurrent protection. In reality, there is NOTHING to prevent drawing 20A from the face connection of a 15A receptacle. And in reality, if the circuit is properly wired, there should be no problem doing so, but my liability insurance won't let me say that.  ;)

For spec-grade receptacles, the innards really are no different between 20A and 15A 120V receptacles -- manufacturers do this to reduce production costs by leveraging economies of scale. For residential-grade receptacles, which are constructed as inexpensively as possible (since paying an extra $500 for quality wiring in a new house is untenable but paying an extra $10,000 for granite countertops is a no-brainer) that may or may not be the case.

(For those outside the United States, "spec grade" refers to a commercial-quality device that generally meets military specifications; sometimes also called "mil-spec". I'm slowly replacing the "residential grade" receptacles in my own home with spec-grade ones because they provide a better connection and are more durable.)
Title: Re: Overseas Power Board
Post by: Mark Cadwallader on July 15, 2015, 03:36:21 pm
Thank you, and thanks also for the clarifying edit to your post I quoted. I was having doubts about my understanding of wiring devices. I'm breathing a sigh of relief now.
Title: Re: Overseas Power Board
Post by: Steve M Smith on July 15, 2015, 03:38:45 pm
It is only rated at 15A through each of the face connections. A device with a 15A plug is not supposed to draw more than 15A

This is why I like our system with a fuse in every plug (although there's nothing to stop someone putting a 13A fuse in when a 3A would be more suitable).

The advantage is that it doesn't matter how many multi way adaptors you connect up, you could have hundreds of things connected to a single outlet, if the load exceeds 13A the fuse will blow.


Steve.
Title: Re: Overseas Power Board
Post by: Mike Sokol on July 15, 2015, 04:21:48 pm

Same with the women here

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Now THAT'S the kind of topic swerve I'm talking about. 8)  Luckily I run a loose ship...
Title: Re: Overseas Power Board
Post by: Stephen Swaffer on July 15, 2015, 06:07:55 pm

(For those outside the United States, "spec grade" refers to a commercial-quality device that generally meets military specifications; sometimes also called "mil-spec". I'm slowly replacing the "residential grade" receptacles in my own home with spec-grade ones because they provide a better connection and are more durable.)

Most commercial/industrial receptacles are not tamper resistant-TR are now code required in homes.  IMO, a better solution would be to use a quality resi grade receptacle-I prefer Leviton, P&S also seem to be good.  TR offers improved safety-especially with toddlers around-they won't be able to copy mom & dad and stick something in the "keyhole".

IF a system is installed according to code, breakers will protect the building wiring regardless of the load that is connected.  Fuses are no longer acceptable for new wiring for just that reason-it is too easy to install a bigger  one when it is not safe.  Fuses in plugs would make sense-plugging a 16 or 18 gauge extension cord into a 15 or 20 amp circuit then plugging in one of these TV advertised "super-efficient" heaters is any easy way to start a fire.  But the fuse holders need to reject oversize fuses to really be effective.  The same person that will use an undersize cord will have no qualms in using an oversize fuse.

What I don't understand is the European and/or Australian use of odd capacities-13 amp/32 amp etc.  I know calculators are everywhere, and maybe I am just mentally lazy, but I find it much easier to derate and figure allowable load for "continuous" etc when I am dealing with multiples of 5 or 10.
Title: Re: Overseas Power Board
Post by: Mike Sokol on July 15, 2015, 08:56:20 pm
What I don't understand is the European and/or Australian use of odd capacities-13 amp/32 amp etc.  I know calculators are everywhere, and maybe I am just mentally lazy, but I find it much easier to derate and figure allowable load for "continuous" etc when I am dealing with multiples of 5 or 10.
Quickly grabbing my calculator, I see that 13 amps times 230 volts equals pretty close to 3,000 watts. Could that be the reason for the seemingly oddball numbers. Do the Brits and Aussie's know something we don't know in the US?
Title: Re: Overseas Power Board
Post by: Mark Cadwallader on July 15, 2015, 09:55:57 pm
Quickly grabbing my calculator, I see that 13 amps times 230 volts equals pretty close to 3,000 watts. Could that be the reason for the seemingly oddball numbers. Do the Brits and Aussie's know something we don't know in the US?

Yes, they do; but even on a loosely-run ship I'll hold those thoughts to myself.
Title: Re: Overseas Power Board
Post by: Steve M Smith on July 16, 2015, 01:20:50 am
Quickly grabbing my calculator, I see that 13 amps times 230 volts equals pretty close to 3,000 watts. Could that be the reason for the seemingly oddball numbers. Do the Brits and Aussie's know something we don't know in the US?
No as it was originally 240 volts until will dropped to 230 volts to be in line with the rest of Europe. 240 x 13 = 3120.

Before we had the 13A BS1363 plug, we had three round pin plugs in domestic use rated at 3A, 5A and 15A.  These were not fused.  The 15A round pin plug remains in use for theatre lighting.

Our industrial connectors follow a strange pattern of current rating.  They are 16A, 32A, 63A and 125A.  It would have made more sense for the last two to be 64A and 128A.

Yes, they do; but even on a loosely-run ship I'll hold those thoughts to myself.
And that!


Steve.
Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 16, 2015, 01:33:18 am
Do the Brits and Aussie's know something we don't know in the US?

It must be metric electricity.
Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 16, 2015, 01:41:50 am
Most commercial/industrial receptacles are not tamper resistant-TR are now code required in homes.  IMO, a better solution would be to use a quality resi grade receptacle-I prefer Leviton, P&S also seem to be good.  TR offers improved safety-especially with toddlers around-they won't be able to copy mom & dad and stick something in the "keyhole".

Since we just adopted our first child (an infant girl), I have identified some commercial grade tamper-resistant receptacles I plan to order and install.

http://www.amazon.com/dp/B004YK6HSQ
Title: Re: Overseas Power Board
Post by: Steve M Smith on July 16, 2015, 02:35:21 am
It must be metric electricity.
In the UK we don't use metric as much as you think we do.

All road signs are in miles, yards and miles per hour and those of us above a certain age use feet and inches.
I use metric for engineering drawings but imperial if I am doing some work on a house.
As the inventors of the imperial system, we are not going to give it up that easily!
 
Since we just adopted our first child (an infant girl), I have identified some commercial grade tamper-resistant receptacles I plan to order and install.
Another advantage of our sockets and plugs is the safety aspect especially with regard to children.  The live and neutral apertures have shutters over them which move out of the way when the earth pin is inserted.  The earth pin is slightly longer so the shutters move out of the way just as the live and neutral pins get inserted.  This prevents children from sticking things into the socket.
 
(http://www.fusionservices.co.uk/productimages/98101848910322.jpg)

And a switch as an added bonus!

The longer earth pin also ensures the appliance is earthed when the plug is not inserted all the way.  It is the first pin to make contact and the last to disconnect.

And on the subject of the plug not being inserted all the way, the live and neutral pins have a plastic sleeve so if the plug is only half way in, little fingers feeling round behind the plug cannot get electrocuted.
(http://www.110220volts.com/Merchant2/graphics/00000001/BS-1363-Plug.jpg)
 
Steve.
Title: Re: Overseas Power Board
Post by: David Buckley on July 16, 2015, 07:33:03 am
The longer live pin also ensures the appliance is earthed when the plug is not inserted all the way.  It is the first pin to make contact and the last to disconnect.
I believe you mean the longer earth pin :)

The picture illustrates a shuttered socket with the shutters opened by means of the earth pin.  A mechanism that can be defeated by using a screwdriver to get your test prods in the live and neutral holes.  An even better arrangement doesn't use the earth pin to open the shutters, but demands equal force from the plug pins onto the shutters whereupon they then open.  Unequal force - no go.  These sockets are far more resistant to inadvertent opening.

 
Title: Re: Overseas Power Board
Post by: Steve M Smith on July 16, 2015, 07:47:26 am
I believe you mean the longer earth pin
Thanks.  Corrected now.
 
The picture illustrates a shuttered socket with the shutters opened by means of the earth pin.  A mechanism that can be defeated by using a screwdriver to get your test prods in the live and neutral holes
I worked that out by the time I was about nine or ten.  I had a few pieces of equipment which didn't have plugs on.  The first version of the 13A plug didn't have the plastic sleeves.  With a plug with all brass pins it was possible to hold the wires at the live and neutral positions and push a plug in which would connect to the wires... apparently!
 
 
Steve.
Title: Re: Overseas Power Board
Post by: Stephen Swaffer on July 16, 2015, 11:26:09 am
In the UK we don't use metric as much as you think we do.


A misconception fostered by our northern neighbors use of the metric system on their highways.  But you don't claim them anymore do you?

I just find it interesting that the same people that encourage the metric system because of its ties to the the decimal system give us a 63 amp 230 volt feeder to apply the 1/8 power rule of thumb to to power amps, where as over here an equivalent feeder is 50 amps at 240 volts-you can figure that one before Mike even finds the power button on his calculator. :)
Title: Re: Overseas Power Board
Post by: Stephen Swaffer on July 16, 2015, 11:28:24 am
Since we just adopted our first child (an infant girl), I have identified some commercial grade tamper-resistant receptacles I plan to order and install.

http://www.amazon.com/dp/B004YK6HSQ

The REAL reason you like those in particular is the first review shown!
Title: Re: Overseas Power Board
Post by: Steve M Smith on July 16, 2015, 11:34:11 am
I just find it interesting that the same people that encourage the metric system because of its ties to the the decimal system give us a 63 amp...
I have no idea where the 63 comes from.  Equally, I have often wondered why valve (tube) heaters are 6.3v.


Steve.
Title: Re: Overseas Power Board
Post by: Tim McCulloch on July 16, 2015, 12:09:07 pm
I have no idea where the 63 comes from.  Equally, I have often wondered why valve (tube) heaters are 6.3v.


Steve.

Something to do with batteries.
Title: Re: Overseas Power Board
Post by: Mike Sokol on July 16, 2015, 01:15:40 pm
I have no idea where the 63 comes from.  Equally, I have often wondered why valve (tube) heaters are 6.3v.
Cause it's half of the center-tapped 12.6 volt heater in a 12AX7. And I didn't even need to power up my calculator to figure that one out. ;D
Title: Re: Overseas Power Board
Post by: Mike Sokol on July 16, 2015, 01:20:01 pm
And don't get me started on AC Frequencies. One of my power station buddies tells me there's still some active 25 Hz AC power for train tracks. And note that in 1918 London had 10 different frequencies in use.

In the early days of electrification, so many frequencies were used that no one value prevailed (London in 1918 had 10 different frequencies). As the 20th century continued, more power was produced at 60 Hz (North America) or 50 Hz (Europe and most of Asia). Standardization allowed international trade in electrical equipment. Much later, the use of standard frequencies allowed interconnection of power grids. It wasn't until after World War II with the advent of affordable electrical consumer goods that more uniform standards were enacted.

Title: Re: Overseas Power Board
Post by: Tom Duffy on July 16, 2015, 01:31:18 pm
Since we just adopted our first child (an infant girl), I have identified some commercial grade tamper-resistant receptacles I plan to order and install.

http://www.amazon.com/dp/B004YK6HSQ

"Hard-use" is how hard, seems like a bit of overkill. Here it is on the Legrand website, wasn't immediately obvious.
https://www.legrand.us/passandseymour/receptacles/fed-spec-grade/hard-use-tamper-resistant/tr5262w.aspx#res

Not sure what the "CP6" at the end refers to.   Note the "upside down" picture though - does legrand endorse the somewhat common practice of putting the ground on top so if the cover plate (which is usually metal in hard-use areas) comes loose and falls off it makes contact with the plug's pin in ground first?
There's no picture of the back:
Residential duplex sockets usually have the ground screw at the bottom, so if this socket has the ground screw at the top, the wiring behind the socket might need some extra twists.   Older houses have very small and crowded workboxes behind the duplex.
Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 16, 2015, 01:35:12 pm
The REAL reason you like those in particular is the first review shown!

Haha, I didn't even look at the review until you mentioned it.

Methinks the reviewer probably had a loose connection, and installing a new receptacle fixed the issue. I'll bet he's a customer of some other sites lampooned in these fora.

Wait... what was the original topic about? This thread seems to have swerved more than a highway in the Alps.
Title: Re: Overseas Power Board
Post by: Mike Sokol on July 16, 2015, 01:41:03 pm
Please make me STOP.  :o

41-2/3 and 45-1/3 Hz.

Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 16, 2015, 01:44:14 pm
"Hard-use" is how hard, seems like a bit of overkill. Here it is on the Legrand website, wasn't immediately obvious.
https://www.legrand.us/passandseymour/receptacles/fed-spec-grade/hard-use-tamper-resistant/tr5262w.aspx#res

Not sure what the "CP6" at the end refers to.   Note the "upside down" picture though - does legrand endorse the somewhat common practice of putting the ground on top so if the cover plate (which is usually metal in hard-use areas) comes loose and falls off it makes contact with the plug's pin in ground first?
There's no picture of the back:
Residential duplex sockets usually have the ground screw at the bottom, so if this socket has the ground screw at the top, the wiring behind the socket might need some extra twists.   Older houses have very small and crowded workboxes behind the duplex.

Re: the back of the receptacle; the feature list includes "Internal screw-pressure-plate back and side wire capability." I'm interpreting that to mean it's the kind where you stick the wire in the back and tighten down the screw; I think that is a superior method to even wrapping the wire around the screw, especially if you are using stranded wire.

My house was gutted then rewired by an electrician in 1996 (previous homeowners suffered a fire which required a complete remodel). So all of the boxes are the plastic nail-on boxes, which have plenty of room. The few that I've opened up have plenty of length on the wire, so it should be no problem orienting the receptacle one way or the other. If a wire does prove to be too short, there should be sufficient space to pigtail it.

Hard use? I'm convinced that residential receptacles actually get harder use than commercial receptacles (except for the ones used for vacuum cleaners), especially in the kitchen.

Sorry, didn't mean to hijack the thread, but everybody else is doing it, too!
Title: Re: Overseas Power Board
Post by: Jonathan Johnson on July 16, 2015, 02:02:28 pm
Another advantage of our sockets and plugs is the safety aspect especially with regard to children.  The live and neutral apertures have shutters over them which move out of the way when the earth pin is inserted.  The earth pin is slightly longer so the shutters move out of the way just as the live and neutral pins get inserted.  This prevents children from sticking things into the socket.

And a switch as an added bonus!

The longer earth pin also ensures the appliance is earthed when the plug is not inserted all the way.  It is the first pin to make contact and the last to disconnect.

And on the subject of the plug not being inserted all the way, the live and neutral pins have a plastic sleeve so if the plug is only half way in, little fingers feeling round behind the plug cannot get electrocuted.

The TR receptacles in the US (which I believe are now required by NEC in new residential constructions) have shutters over the live (hot) and neutral (groundED) slots. The shutters cannot be moved unless equal pressure is exerted on both simultaneously. Using the groundING pin to open the shutters doesn't work here, due to the large installed base of two-prong plugs. Every table lamp and double-insulated appliance uses only a two-prong plug.

I do wish, however, that our plugs had the insulated sleeves on the back part of the prongs like yours do.

For our three-prong plugs, the earth (groundING) pin is longer. But the quality of most plugs is so poor (thanks, China!) that the earth pin is easily broken off.

On a side trail of this side trail, it's interesting to note the difference in terminology between the UK and the US (and the NEC):

Quote
UK vernacular=US vernacular=National Electrical Code terminology
---------
Live=Hot=Current Carrying Conductor
Neutral=Neutral=Grounded current carrying conductor -- but doesn't really exist as such in the UK, does it?
Earth=Ground=Equipment Grounding Conductor (EGC)

The National Electrical Code (NFPA 70) did not even define "Neutral conductor" until the 2008 edition of the code, and at least one interpretation of the definition says that on a 120V circuit single-phase circuit, what's called 'neutral' in the vernacular isn't even neutral:
http://www.ecmag.com/section/codes-standards/neutral-or-not
Title: Re: Overseas Power Board
Post by: Stephen Swaffer on July 16, 2015, 02:11:51 pm

Sorry, didn't mean to hijack the thread, but everybody else is doing it, too!

"Everything rises and falls on leadership"!!