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"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
An RCD isn’t necessary in any modern house because the distribution unit has them on the individual circuits, although it might be a good idea if you’re playing somewhere you’re not sure of. But be aware that they don’t lift the earth connection so they don’t guarantee safety - the biggest risk when playing an instrument is a shock via the earthed strings from some other source, typically a mic on a different supply.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Earth faults are surprisingly common in these environments, partly because of the total bodges musicians and their 'technician' bring into the venues but also due to the lack of proper maintenance in these locations. There's also so many rumours flying around like 'RCDs change the sound of my amp' (which is bollocks of course) which means we end up with people bypassing safety devices! As the onsite electrician I have had to take stuff off musicians so many times because it is a shock or fire risk!
There's an entire set of British Standards relating to this sort of installation but I've rarely ever found a theatre spark who knows about them, never mind actually owning a copy!
Anyway, minor rant over.
There are some others where the electrical ground is lifted slightly from the mains earth to minimise hum loop problems, but there's still a low enough resistance between the two that it doesn't help (typically 10 ohms).
Exactly - the most common being lifting the earth connection to break a ground loop, rather than doing it properly in the signal path. I have completely lost count of the number of amps and effects units I've repaired and had to re-connect the earth. I'm sure it won't have made me popular with some owners either! But tough...
Likewise replacing dangerous old mains connectors like Bulgins with modern IEC ones. A lot of vintage amp owners really don't want this done because they think originality is more important than safety or reliability - which is fine, I just won't work on your amp... and it will be returned with the plug removed.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
@ICBM will know a lot more about the inner workings of appliances and assemblies as I mostly work on fixed and temporary installations and rarely work on appliances.
EDIT: https://www.screwfix.com/p/lap-ms6860d-socket-tester/91596
The tester won't tell you if the earth is good or not (or earth-neutral reversal) but it will at least tell you that there is something connected to the earth contact.
I am a bit paranoid with my own gear - having once got a 'cross wiring' shock at a venue. Admittedly this was in the bad old days before RCDs on all distribution boxes. I disconnect the string ground from my guitars/basses and fit a high-voltage cap in series with it. This maintains the noise suppression while isolating the strings from the direct connection to the earth. It's not foolproof though - you could still get a shock from any other metal parts that are still directly grounded - pickup covers, metal control plates etc - and from the jack plug. But I think it's still better than nothing, and a lot simpler and cheaper than an isolating transformer.
But don't worry *too* much - you'd be pretty unlucky to get a shock in any decent UK venue now, if your gear is properly checked or certified. Don't feel it's an imposition or 'nanny state' rules to have it properly tested, if you're not sure - the idea is to not die.
Of course if you want to be truly safe on stage, just use wireless for both the guitar and the mic...
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
*An Official Foo-Approved guitarist since Sept 2023.
OP, keep in mind that the fuse in the plug top is there to protect the cable and equipment. It does not protect you from receiving a shock if something goes wrong in the equipment.
Nil Satis Nisi Optimum
If you're near Islington pop to Grahams HIFI and get one of the blocks they make themselves. ps not silly Nordost money.
https://www.amazon.co.uk/Duronic-ST12B-Extension-Engineered-protected-Black/dp/B005191K54/ref=sr_1_1?ie=UTF8&qid=1544634571&sr=8-1&keywords=duronic+st12b
Seem to work well.
https://speakerimpedance.co.uk/?act=two_parallel&page=calculator
Also is it bad to plug an extension into another, and at some gigs I've seen people, another? Wouldn't it cause overheating?
Longer answer:
All power strips complying to the relevant British Standards (i.e. anything you buy in a UK shop/supermarket/Argos but not some cheap shit you bought from eBay China or Alibaba) should have a fuse in the plug protecting the cable and anything plugged into it. The cables and contacts will also be manufactured to the right spec to stand the maximum potential current. Much kit we guitarists use doesn’t draw much current so you’ll probably be okay.
That said, if you don’t unreel your cables or run them where the heat can’t escape it’s very easy to overload them. A 13A fuse doesn’t go bang at 13.1A, it actually takes nearer 20A to go
bang instantly and I could easily draw 14A through a 13A fuse pretty much indefinitely. Anyone who has ever plugged two fan heaters into an extension cable will know the extension cable gets VERY hot.
The recommendation for power cables at festivals/shows is to have them wired in rubber cables generally in a larger cross sectional area than used for a domestic cable to
avoid exactly this. We usually specify tougher plugs and connectors for the same reason.
If I’m wiring up a stage I usually have a circuit of plug boards chained together around the stage for the musicians to plug their guitar amps, keyboards whatever all on one 16A circuit. Separate circuit for monitors, separate circuit for front of house, separate circuit for lighting and a circuit for heaters too. I always use quality kit and not just Woolworths special £2.99 jobbo.
We are fortunate to live in a country with the best electrical system in the world - as Simon_M says, as long as everything is to the correct spec and the plugs have the right fuse value for the cable then you can't dangerously overload anything without a fuse blowing.
I've also personally seen a coiled-up extension cable melt when a band - not one I was working for! - didn't understand that the rating is reduced when it's left on the reel... this is not an idle warning, it started smoking and when they tried to pull the cable out it was just a big sticky mess inside.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein