Getting power? 50 Amps?

[beam_1973]

10, 15 and 20 amp sockets are physically smaller and also need an adaptor, and careful thought so you don't overload them.
This is a 50 amp Clipsal outlet a la the type in question:

I have worked a few Sydney venues where the 3 phase outlet is rated at 20amps, yet the male plug on the end of the dimmer rack cable is remarkably similar to any other one I have seen (that I would assume plugs into a 32 amp 3 phase outlet) with no adaptor present. Is it possible for someone to just rewire the dimmer rack cable with a 3 phase 20 amp plug?

CAC

 

[Logos]

This is a very dangerous statement without actually seeing what you are talking about but I have come across 3 phase outlets with a standard 32 amp socket that have 20amp circuit breakers. This is usually because of supply issues into the building. It would be important to watch your loading of any dimmer rack in that situation.
Normal 15 and 20 amp plugs in Australia are single phase.

 

[Edrick]

400 AMP GFCI

Atleast according to google.

 

[Peter]

If you want to spend some time browsing lots of power options, check out: http://lexproducts.com I've never bought anything from them, but I have a friend who works there and they have all kinds of power disto stuff that's always fun to look through!

 

[Chris15]

I have worked a few Sydney venues where the 3 phase outlet is rated at 20amps, yet the male plug on the end of the dimmer rack cable is remarkably similar to any other one I have seen (that I would assume plugs into a 32 amp 3 phase outlet) with no adaptor present. Is it possible for someone to just rewire the dimmer rack cable with a 3 phase 20 amp plug?

CAC

Absolutely. Buy the rack unterminated and a quick visit to your electrical wholesaler later you have a 20 amp plug. Then just terminate. The 10-20 amp sets are a smaller diameter than their cousins. But unless you know what you're looking for and have decent light, it would be quite easy to mistake one for the other.

For what it's worth, the adapter in question is a 32 amp socket, a metre or two of flex and a 10, 15 or 20 amp plug. Not some moulded thing since you technically shouldn't be doing this... Oh and I'd be questionable as to whether you could test & tag it as well.

This is a very dangerous statement without actually seeing what you are talking about but I have come across 3 phase outlets with a standard 32 amp socket that have 20amp circuit breakers. This is usually because of supply issues into the building. It would be important to watch your loading of any dimmer rack in that situation.
Normal 15 and 20 amp plugs in Australia are single phase.

Err. There are a fair whack of lower amperage 3 phase connections out there. A bowling club might have a 4 pin 10 amp for the green roller. (Happens). Many big motors will use 3 phase because you can get more efficiency out of it and also because reversing is much easier - eg. industrial roller doors, though they don't normally have a plug & socket.

Large cooking appliances are also a sucker for 3 phase, usually 4 pin. Large ovens etc. normally though sometimes cooktops as well - they tend to have neutrals. This is why the kitchen at my old school had a 3 phase 15 amp socket or two. For the teacher's in bench cooktop. Welders are something else where low current three phase can be found (or high current depending)

And then you get the idiots who thought that a 20 amp socket would do in lieu or 32... no comment. At least put the socket in even if you under breaker it. At least I don't need an adapter...

 

[JD]

To help provide clarification, I have attached an image showing the three forms of 3 phase power found in the US that provide 120 volt legs. (Remember, there are other systems in use such as 480v which can not be used without transformers! ) The types shown are Delta, Wye, and Center tapped Delta. Of these, only the Wye (Y) configuration are usable for 3 phase dimmer systems. In these systems, you will find 120 volts between any phase leg to neutral. You will also find 208 volts between any two hot legs. I have found the Center Tapped Delta in many of the older buildings and warehouses I have worked in. Basically, it can be used as a single phase power source. The bottom leg is center tapped providing 120-0-120 volt configuration. (The same as residential power.) WATCH OUT FOR THE THIRD LEG, often called the "Wild Phase", it is 208 volts with respect to neutral.
The "Floating Delta" is the one that can trip you up. The panel I found in 1983 had a false neutral connected to the ground. It measured 120 from all three phase legs to neutral, and 0 volts from neutral to ground. You will get these readings because there are bleeder resistors (not shown) inside the transformer to drain static. Since your meter does not really place a load on the system, it will appear as Wye. The tip off was 240 volts between each of the hot legs.

 

[SHARYNF]

JD is absolutely correct. The center tapped delta is used in buildings where there is a need for lighting, so that you can have 120 volts, and there is a need for the full 240 volts for equipment, and at the same time for motors there is the three phase delta. It has advantages typically for a placed where the equipment needs the full 240 volts and the 208 causes in effeciencies (heaters and cooking gear etc) It was designed so that you have these three options BUT just as jd said your standard three phase distro should NOT be connected to it.

Three phase y works best for theatrical purposes BUT remember that if you are running 240 volt gear, you will ONLY get 208 volts.

Sharyn

 

[stantonsound]

Last night I was setting up a show at a very nice hotel in downtown Charlotte, and was using 12 movers. I had requested a 60amp power drop to make sure I had enough power. They provided me with a single phase, 60amp line that had three edison receptacles on it. The problem with this is that there is no real protection from a circuit breaker, as there were no individual circuit breakers for each. It would not trip unless the entire circuit hit 60 amps. The cost for this was $150.

Also, a little off topic, but somewhat related. We were hired to create mood and excitement to the cocktail reception in the pre/post function area. The other lighting company that was there did the main event stage lighting (corporate event). They had a bunch of truss rigged, as well as pipes on the airwall hangers. I was talking to their production director and he said that they were charged a rigging charge to be allowed to hang points. They were charged $50 per point (to rig it themselves - $250 to have the house staff rig it) and $500 flat fee for hanging on the airwall tracks. So, to push the ceiling tile up, and to wrap a spanset or cable around the building steel, it was $50. With the spandex structures, confetti cannons, and other things hanging, there were more than 20 points.

 

[jonhirsh]

$50 is kinda low for that. I know people who have been charged up to 200 per point and 300 to have it done for them.

JH

 

[beam_1973]

but I have come across 3 phase outlets with a standard 32 amp socket that have 20amp circuit breakers. This is usually because of supply issues into the building. It would be important to watch your loading of any dimmer rack in that situation.
Normal 15 and 20 amp plugs in Australia are single phase.

Hmmm, well the venue in mind has a 3phase socket that is labelled 20amp, so it may just be a diameter difference between it and the 32 amp version I guess. Either way, I still only load to 20amp capacity.

The 10-20 amp sets are a smaller diameter than their cousins. But unless you know what you're looking for and have decent light, it would be quite easy to mistake one for the other.
And then you get the idiots who thought that a 20 amp socket would do in lieu of 32... no comment. At least put the socket in even if you under breaker it. At least I don't need an adapter...

Ahh, yes, diameter ... that would be it ... thank you. And yes, it would make sense to install a 32 amp socket, label it as 20 amps and breaker it at 20 amps (if that what the actual supply is) ... avoid having to use these adaptors altogether huh! Thanks for the advice!

 

[Chris15]

And yes, it would make sense to install a 32 amp socket, label it as 20 amps and breaker it at 20 amps (if that what the actual supply is) ... avoid having to use these adaptors altogether huh! Thanks for the advice!

Now I'm guessing that when you refer to labelled, you're referring to the labels imprinted on the socket itself. These are put there during manufacturing and will be the rated capacity of the socket. These aren't necessarily the breaker ratings. It's like the 1k2 dimmers that show up from time to time. hey are fused at 5 amps, but they've got a 10 amp socket, and the plastic of the socket will still say 10 amps... If that makes more sense. Oh and the diameter difference is only about 10mm between 20 & 32 amp. The outer of a 20 amp plug is pretty close to the diameter of the inner ceramic on a 32 amp socket if that helps visualise it...

 

[Radman]

Back to the order of connect/disconnect, in which order do you connect line/load ends? Line first, then load? Or load then line? Or does it matter?

 

[stantonsound]

If the power is turned off, it shouldn't matter. I personally prefer to connect the cams to the wall, and then to the dimmers. My biggest concern in working with electricity is getting in between the neutral legs. More electricians are injured by getting in between the neutrals than touching the not leads. If I connect to the wall first, I do not have to worry about getting in between the neutrals just in case someone turns it on.

If, on the other hand, the dimmers are far away from the cam/panel and I can not see the switch, I will hook up the dimmer rack first and then hook up the panel. This prevents me from getting injured if someone turns on the power (despite a lock out/tag out).

 

[beam_1973]

Now I'm guessing that when you refer to labelled, you're referring to the labels imprinted on the socket itself. These are put there during manufacturing and will be the rated capacity of the socket. These aren't necessarily the breaker ratings. It's like the 1k2 dimmers that show up from time to time. hey are fused at 5 amps, but they've got a 10 amp socket, and the plastic of the socket will still say 10 amps... If that makes more sense. Oh and the diameter difference is only about 10mm between 20 & 32 amp. The outer of a 20 amp plug is pretty close to the diameter of the inner ceramic on a 32 amp socket if that helps visualise it...

Chris ... yes and no ... I meant use a 32amp socket (with manufactured label), use a 20amp breaker on it, but install a label above/next to it stating that its only capable of 20amp load (in case breakers aren't immediately next to it, so people don't get confused as to why it might be tripping)

And cool, thanks for the info on the diameter difference between 32 and 20, will help greatly in the future!

 

[SHARYNF]

Just to clarify, the breaker is designed to protect the path from the equipment to the breaker from overload, so the wire, connectors etc is what is being protected, it is NOT the equipment.

Where you can get into problems is when the wire to the socket say is rated for 30 amps, and so it the connector, but the wire that goes from the plug in the socket to the equipment is only rated for 20 amps, you then have a situation where part of the wire could over heat.

Sharyn

 

[stantonsound]

Actually, I was always taught that the breaker is designed to protect YOU from the overloaded circuits, and to prevent a fire. It will prevent damage in most cases for devices like motors, conventional lighting fixtures, and other "heavy duty" devices, but rarely electronic devices such as movers (that is why they have protection built in).

 

[Chris15]

I think I'm between those two viewpoints... It's there to stop the wiring from overheating and starting an electrical fire for sure. The protection of humans is also an important factor. You short out active and neutral and there is not a safety switch on this planet that will help. But a breaker will trip pronto. Hopefully this will be leading to saving of your life.

Underrated extension leads are also a thing one needs to be careful of. Down here 10 amp is standard and use 1.5mm2 cable. However you also get stuff only rated to 7.5A which uses 0.75mm2 cable. But there is absolutely nothing stopping you from plugging in a 10A load to one of these. Same socket. When the proper cable gets warm under full load sometimes, I'd hate to think what the crappy stuff would do.

Big motors need special breakers so that they don't trip on the inrush current. I believe you would use a D curve breaker in lieu of the standard C curve. And the bottom line in all of this is that a fuse is still much more sensitive and faster acting, but harder to 'reset'.

These things can also play a role in protecting supply components, eg. in dimmers. Over current will cook triacs for instance.

 

[stantonsound]

Here's a few conversions for us yanks that don't understand all that mmsquared stuff.

AWG Cross Sectional Area (mm2)

12 3.31
15 1.65
18 0.82
20 0.52




Anyone else do this??????
Personally, I use 10 gauge 12/3 SO for my 100+' cables. (The real reason is that I got a GREAT deal on 10/3 a while back and bought 1000 feet of it, so I made 100 and 200' cables). It is a little heavier, but I think that it is a little safer and has far less voltage drop for the long runs than the 12/3.

 

[Chris15]

15 Amp and "heavy duty" are 2.5mm2 cable. Legally you can't have an extension longer than 30m down here = 100' for you lot. Those who make their own cables will sometimes choose to make these long ones in 2.5mm2 cable for voltage drop etc. reasons...

 

[SHARYNF]

Actually, I was always taught that the breaker is designed to protect YOU from the overloaded circuits, and to prevent a fire. It will prevent damage in most cases for devices like motors, conventional lighting fixtures, and other "heavy duty" devices, but rarely electronic devices such as movers (that is why they have protection built in).

GFI's are designed for your protection, but the NEC for standard breakers is just directly for the wire