Curiosity got the best of me and I had to see if my $3 tester would see something amiss. The outlet on the right has the hot/live AC wired to the ground lug and the real ground and neutral to the 'blade' connections. Even if hot/live and neutral to the blades were reversed the tester indicates incorrect wiring. Just trying to understand how it could be mis-wired so the tester doesn't properly show incorrect wiring, at least on a typical US outlet.What's Shark Tank? TV show?
He's been the head of engineering for Peavey, most of his professional life. He and his company got sued by the family of a guitar player who died because of a wall socket that had live connected to ground. None of the 3$ tools will "see" that as a fault, while it's deadly.
In most systems here, we no longer have "polarity". Symmetrical. But a hot ground would be noticed immediately, because ground connection protrude from the sockets:
Just trying to understand how it could be mis-wired so the tester doesn't properly show incorrect wiring, at least on a typical US outlet.
What's Shark Tank? TV show?
US folks.......
Which do you see predominately?
Ground Pin Up or Ground Pin Down? - archtoolbox.com
Every one I've ever installed has the ground pin down.
US folks.......
Which do you see predominately?
Ground Pin Up or Ground Pin Down? - archtoolbox.com
Every one I've ever installed has the ground pin down.
"Symmetrical" mains supplies are rare here outside medical/lab facilities. Such systems can be dangerous to unsuspecting service personnel since a mains fuse can blow but leave 120v 'live' above earth. 55V is not QUITE so lethal!
US folks.......
Which do you see predominately?
Ground Pin Up or Ground Pin Down? - archtoolbox.com
Every one I've ever installed has the ground pin down.
There's nothing in the NEC that covers this. However, the logic behind 'ground down' is this: in a situation where something or someone has fallen or knocked a cord connected to the receptacle nearly out of place the LAST thing you want to disconnect is the built-in safety. This something that is the choice of the electrician responsible for the installation. In the early and mid 70's there was a whole discussion about which was more safety oriented, ground up or down. Us old electricians always prefer it down for the reasons I outlined. However....designers have other ideas about these things at times. Even horizontal mounting. In recent years the manufacturers have started building a horizontally oriented recept in all sorts of bright designer colors.
Personally I use hospital grade devices in my studio. Even iso-grounded plugs where required.
My own opinion is you likely won't find a residential 'electrician' that's versed in troubleshooting EMI or other types of 'noise' that is internal to house wiring, particularly if it's related to studio which he/she wouldn't have any experience with (unless a studio owner themselves).
What sort of problem are you having? Is the problem localized to a specific room and isn't present elsewhere in the house?
POWER QUALITY ANALYZER PQ3100 - Hioki
How do you know it's EMI...?
As has been said, it will be easier to advise if you give us a list of the gear and the precise nature of the interference.
Dave.
How do you know it's EMI and not RFI, a ground loop, or another cause?
Why don't you simply ask your questions over the phone with them before you hire them? Most electricians are conscientious and fairly intelligent individuals who rely on word of mouth as well as their media coverage to buoy their reputations. At least for the smaller shops. Just because a person has some knowledge of studio work and the gear associated with one doesn't mean they know squat about electrical current and the containment and transmission of such. In my experience with electricians (35 years as a Journeyman) most will NOT raise their hands "just to give it a try" especially with something as specific as what you are experiencing. I have no idea what type of training and schooling is a requirement in Michigan, but most places with a strong union presence in a trade has schooling programs that cover a lot of things even if a person becomes a "residential electrician" as his business.
My suggestion to you, as a truly qualified individual (REAL electrician and studio owner for many years) is to google EMI or RFI however you want to define it and learn about the causal effects from such a thing and apply it to your situation. Real knowledge on a subject can take you a long way towards solving a problem that is more than likely an easy fix and something as simple as having the wrong things on the wrong phase in your building as the studio power.
The BEST and easiest (not the cheapest) is an isolation transformer of the proper voltage and wattage rating for your requirements. IF this is that important. I have no idea whether you are selling time to others or simply funding your own projects, but this would be something to consider.
If you have a lot of rack gear and there is a chassis ground on the frame (the green connector usually on the back marked "chassis ground") you should have all pieces with this feature tied together and sent to an 'earthing ground' separate from the common power. DO NOT tie this to your panel. Two paths to ground through the common grounded buss could mean some serious shock.
To be a studio owner you should always know things like this. What is the difference between 'grounded' and 'grounding'. How does RFI get into your signal chain. How much free air space is required to keep power and signal separate.
It's really simple when you understand how it works.
If the PU's on the guitar are single coil they may tend to pickup 'stuff' floating around in the air and if you move around it may change. Humbucker PU's are less susceptible, but may pickup something if strong enough. If you touch the strings or metal tail piece on the guitar does the 'EMI' change or go away? Was the SM57 micing an amp?I hear what I could best describe (and what I've seen described from others as EMI. I experience this with my guitar and I just noticed it while recording with an SM57 the other day. If I move to a particular position it goes away but that's a very small window.
I'll double check to see if I experience this in other rooms. If I recall correctly, I did experience it in another room (dinning room upstairs). My studio is in my basement.
That’s the common usage in new construction. The thing that’s not consistent is sometimes only one of the outlets is actually switched!I have to go through my house to look, but I remember in previous houses, the upside down outlet would mean it was connected through a wall switch.
If the PU's on the guitar are single coil they may tend to pickup 'stuff' floating around in the air and if you move around it may change. Humbucker PU's are less susceptible, but may pickup something if strong enough. If you touch the strings or metal tail piece on the guitar does the 'EMI' change or go away? Was the SM57 micing an amp?
first thing i would do is go to home depot and buy you one those cheap plug in outlets tester. that'll show you first it is wired correctly, and also check any ground or neutral problems in the wiring. Also certain types of lighting fixtures and light switches will induce some hum, especially if they are on the same circuit . i have three separate circuits in my bedroom studio and have no problems. of course they are dedicated only to studio equipment use. then again i did wire it myself.