Any sparks here ?

Emp_Fab

Our bassist has come up with an idea to reduce the setup time for gigs by creating two 'umbilicals' - one for power and the other for signals.  i.e. a single long power cable with 4-way sockets spliced in at the appropriate places for the various members, and the signal one would be basically all the leads cable-tied into a bundle, kind of like a stage to mixer snake, with the relevant inputs exiting at the correct places (we all retain the same relative positions).  We could then keep the signal leads permanently connected to the mixer and just unroll the umbilicals and plug in.

My question is this....  even though the total current draw is nowhere near the limit of a single 13A plug, is there any risk in having a single cable with, say, 5 x 4-way power strips spliced in at various points along its length ?  Our drummer seems to think this is a fire hazard, but I disagree.  I say it's no different from a single 20-way power strip and, as long as the current draw is less than 13A, there's no safety issue.

Could any electrickery types comment please ?  Ta.

hywelg

A solution looking for a problem.

Just cable tie a few mains extensions leads together. And the signal cable, well its called a snake and you can buy them.  In fact I have two 15m ones I tried to sell a while back and then forgot about them.

And it'll only work if you always have the desk/mains supply the same side of the stage. And the bassist /guitarist/singist will always have to stand in the same relative positions.

Hoof

Certainly not a fire hazard or unsafe in any way but even if you've added your current draw up correctly it's still pushing your luck to hang the entire band on a single 13A fuse. Surges or a failure in a single piece of kit could result in silence. Daft to kill the whole band if the failure is a single light or amp.  We've probably all done similar things in the past where the "venue" has a single socket outlet but it's not a risk I enjoy taking.

Extension cables are easily damaged too. If this causes earth leakage and the sockets are RCD protected (as they should be) what would you do when the RCD keeps tripping because your dodgy cable has developed a fault?

If you're really determined to do this run it off 2 plugs. That way you get 26A total(assuming the socket circuit is a 32A ring) and some discrimination between things. Maybe run it as:

Cable 1 - essentials/sound: PA,Guitar and bass amps.
Cable 2 - Lights, fans, Monitors if active, 

That way if something like the sweaty drummer's fan fails and blows the fuse then you still get through the set.

Hoof

"a single cable with, say, 5 x 4-way power strips spliced in at various points along its length ?"

What do you mean by spliced? Remember, if you have your gear PAT tested a McGuyvered solution to joining cables is extremely unlikely to get a pass.

Even if this is done well it would still be vulnerable to damage.

If you find set up is taking too much time then maybe you should look at your band's routine and see if everyone is actually pulling their weight here. Or maybe you have more gear than you really need?

Handsome_Chris

As someone who used to do the PAT as part of my previous job as a technician, this is not a good thing to do. You are importing unnecessary risk.

mistercharlie

Handsome_Chris said:

As someone who used to do the PAT as part of my previous job as a technician, this is not a good thing to do. You are importing unnecessary risk.

What’s the risk, though?

siremoon

Seems to me to be something which would take a lot of work to put together properly and safely with no obvious upsides and plenty of downsides.    

Emp_Fab

mistercharlie said:

Handsome_Chris said:

As someone who used to do the PAT as part of my previous job as a technician, this is not a good thing to do. You are importing unnecessary risk.

What’s the risk, though?

That's my question too..  which aspect of connecting them in series like this makes it more dangerous, and why ? 
I'm sold on @Hoof 's argument about single point of failure so it's probably not going to happen now, but I'm very intrigued by the technical explanation of why it would be more dangerous.

ToneControl

The things you need to be wary of with this scenario are:

• coiled cables - when you use an AC power lead that is on the reel, it heats up (because it's a coil), so typically a 13A extensions is only rated at 3A when not extended fully. So don't buy a longer cable than you need and leave half on the reel
• Cable ratings: The amount of current a cable can handle is based on the thickness of the wires. Thinner wire has a higher resistance
• Voltage drop. Believe it or not, the voltage can drop quite a bit if you have a long cable. If I run power tools from the 70m long extension at the bottom of our garden, they run noticeably less powerfully than when plugged into a house socket
• having a daisy chain of extension 4 way sockets would mimic a mains spur in the house. The trouble is, you 'd be moving it all the time, probability of losing all the power to more than one person is increased. Also home-made connections/mechanical fixings are usually less reliable than factory assemblies (unless you get a Pro involved).
• It would be safer to just use several long power extension leads in parallel, tied together with plastic ties. As mentioned, don't make it too long that you will leave it coiled up at the plug end

ESBlonde

One big cable gets abused as it's coiled up because it's heavy. Also it belongs to nobody so always gets left to you. It takes away flexibility and means you can't swap out a spare 4bar lead to get everything downstream going again. If it gets forgotten you are buggered. It needs to be the right length for every venue because you must uncool all of it to avoid it overheating and catching fire. The effort required to make It out weighs  any obvious benefits.
Yes to audio multicores. No to power,  remember power and audio are best crossed at right angles not run alongside to absolutely avoid ' noise'.

siremoon

Emp_Fab said:

mistercharlie said:

Handsome_Chris said:

As someone who used to do the PAT as part of my previous job as a technician, this is not a good thing to do. You are importing unnecessary risk.

What’s the risk, though?

That's my question too..  which aspect of connecting them in series like this makes it more dangerous, and why ? 
I'm sold on @Hoof 's argument about single point of failure so it's probably not going to happen now, but I'm very intrigued by the technical explanation of why it would be more dangerous.

How do you intend to physically connect them?  Is there such a thing as plug board blocks that accept 2 cables?  I've never seen one.  So you will probably have to alter the casing of the block to provide cable access for the second cable.  That starts to create increased risk and is moving into bodge territory.

If you are really desperate for this one cable approach then just plug each extension into one of the sockets on the preceding one to make a long cable with intermediate sockets. 

Handsome_Chris

Emp_Fab said:

mistercharlie said:

Handsome_Chris said:

As someone who used to do the PAT as part of my previous job as a technician, this is not a good thing to do. You are importing unnecessary risk.

What’s the risk, though?

That's my question too..  which aspect of connecting them in series like this makes it more dangerous, and why ? 
I'm sold on @Hoof 's argument about single point of failure so it's probably not going to happen now, but I'm very intrigued by the technical explanation of why it would be more dangerous.

The harness should ideally be layed out to prevent damage to the insulation, not coiled up at one end because you may not need it that long for the venue.  If you are power equipment close to the leads capability, then if coiled the lead may overheat and cause the insulation to melt.  This may result in a short circuit, at which point the wall socket goes from trying to supply up to 13amps to trying to supply a buttload of amps.  This is the point where the venue's circuit breakers should take over and switch off the supply to all your gear .

The idea of splicing theses trailing sockets onto a mains cables sounds very suspect: would you be using crimps or terminal strips (chocolate block connectors)?

spark240

If you really want this method, I would get a length of 2.5mm 3c heavy duty flex, then connect a few twin ALM sockets at intervals to suit, say 3-4m spacings. Use compression glands in and out of each socket with cable tie on the inside, and stick and RCD plug on the supply end. This should take a pretty heavy battering for a while.

That said...Ive never found the need for such an invention.

Hoof

siremoon said:

Emp_Fab said:

mistercharlie said:

Handsome_Chris said:

As someone who used to do the PAT as part of my previous job as a technician, this is not a good thing to do. You are importing unnecessary risk.

What’s the risk, though?

That's my question too..  which aspect of connecting them in series like this makes it more dangerous, and why ? 
I'm sold on @Hoof 's argument about single point of failure so it's probably not going to happen now, but I'm very intrigued by the technical explanation of why it would be more dangerous.

How do you intend to physically connect them?  Is there such a thing as plug board blocks that accept 2 cables?  I've never seen one.  So you will probably have to alter the casing of the block to provide cable access for the second cable.  That starts to create increased risk and is moving into bodge territory.

If you are really desperate for this one cable approach then just plug each extension into one of the sockets on the preceding one to make a long cable with intermediate sockets. 

I wasn't suggesting running 2x plugs/leads into a single multi-way, sorry if it came across that way. I was simply suggesting that 2 fully seperate cables was at least better than a single one,in terms of current carrying capacity and discrimination in the event of a fault. ToneControl's contribution regarding Voltage Drop is important to consider if you were thinking about making the cable long. 

That said, the whole thing is just an embarassing failure waiting to happen. Just make each band member individually responsible for their own power requirements and a specific part of the PA/lighting rig. My own rig is a head/cab/pedalboard/2x guitars set up and without rushing it takes me 10 minutes to set up, including tuning guitars. I don't touch that until the PA and lights are set up and operational. In my band if someone started fannying about with their own kit before the communal stuff is sorted they would be pulled up about it pretty quick.

57Deluxe

this thread is looking more like Amateur Hour by the minute...

Emp_Fab

....and do you have some professional advice for all the amateurs here then ?

Keefy

I looked at this a few years ago for a band I was in that used a large number of 4-ways in a mixture of daisy-chain and branched configurations. The closest I got was a system of 4-ways where each block has a male connector at one end and a female connector at the other. However this was intended to be installed semi-permanently in, say, an office, not moved from gig venue to storage box to gig venue. It was also hugely expensive.

EDIT: I've just remembered what drove this. The singer was fond of bringing the lights in at certain times for dramatic impact. I was playing guitar synth at the time, and the sudden current draw from the PAR bulbs would cause a brown-out, making my guitar synth reset to patch A01; thus my carefully crafted faux-sax part would suddenly turn into a shonky piano riff.

It's better to branch several multi-ways from one rather than daisy-chaining them, and keep the number of stages in the daisy-chain to a minimum, as each plug-to-socket connection will lose you some voltage and is another potential failure point. Also go for chunkier conductor cores, usually evidenced by chunkier overall cable diameter.

For another band, I did once make up a loom of all the mic cables, monitor line feeds, and speaker cables, bound together with cable ties. That worked and saved some setup time.

midlifecrisis

a previous band i was in, the drummer was a qualified electrician and rigged up a sort of portable ringmain, plugged in one end and various socket boxes neatly distributed across the stage. It always worked but took just as long to set up and pack away as everyone singly having their own power and extension leads. I proved this to him and he got a bit upset, as he always liked to make and fix stuff (shame he was a mediocre drummer)

ICBM

One advantage of it would be that, contrary to popular belief, it is actually safer to have everything connected to a single wall socket - assuming that's possible because the total current draw doesn't exceed 13A of course.

The reason for this is because - assuming all your extension cables are properly checked - it makes it impossible for the earth connection on one piece of equipment to become live relative to the earth connection of another, which is the most dangerous of all situations - if a person contacts both at the same time, most often a guitar to a microphone, the live leak will take the available path to earth... through the person.

But as Keefy says, the ideal arrangement is not a daisy-chain - it's a tree-branch system. You need to have one four-way extension plugged into the wall, four more 'subgroups' plugged into that, and so on until you have enough available outlets. That ensures only one earth connection and individual fusing for each sub-group. Even better, if you know each subgroup has to handle much less than 13A, you can fuse each one at 5A, so if something goes wrong it probably won't blow the fuse at the wall, which makes finding the problem simpler.

I would try to keep lights on a completely separate circuit if at all possible though, or at the very least a dedicated subgroup, given their high current draw.

Keefy

^^ In my home studio I have installed a 6x6 branching system, i.e. six 6-ways coming from a further 6-way plugged into the wall socket. The plug at the wall has a 13A fuse, and the plug of each branch has a 3A fuse. I used to have a lot of these in use at any one time, but since my move to a computer-based DAW, my outboard gear has steadily been whittled down.

A lot of stage lights now use LEDs, which consume much less power.

ICBM

It's also worth mentioning [putting patriotic hat on ] that the UK's system with a fuse in each plug, is the best in the world. If you make sure that any extension is correctly fused for the cable size, and that all the connections are in good condition, you cannot overload anything no matter how much you daisy-chain or tree-branch multiple extensions, because the relevant fuse will always blow first.

The only real dangers are that you can put a 13A fuse in an extension with lower-rated cable, and that poor connections can introduce enough resistance to be a fire risk before the fuse blows. But it's still safer than any other system.