Detecting AC electric field strength with a multimeter

[Hardwire]

At work I sit right next to a giant 3 phase 480V-input to 3 phase 208V/120V-output power distribution system (literally about a meter away from me). I'm wondering how substantial the AC field is, being so close to it, and I was wondering if it could be measured by creating some sort of tuned electric field antenna and a multimeter or oscope.

Google isn't helping much at the moment, and I couldn't readily find anything searching the forums...

Is there any easy way to do this with a multimeter + some small "antenna" that I could make out of a few components? I have a decent electronics lab at my disposal. I'm in the US so the mains are at 60 Hz.

 

[Optikon]

At work I sit right next to a giant 3 phase 480V-input to 3 phase 208V/120V-output power distribution system (literally about a meter away from me). I'm wondering how substantial the AC field is, being so close to it, and I was wondering if it could be measured by creating some sort of tuned electric field antenna and a multimeter or oscope.

Google isn't helping much at the moment, and I couldn't readily find anything searching the forums...

Is there any easy way to do this with a multimeter + some small "antenna" that I could make out of a few components? I have a decent electronics lab at my disposal. I'm in the US so the mains are at 60 Hz.

The sensitive DMM's that I use pickup 60Hz quite nicely.. just need a big loop of wire, you can spot it easily.

usually an open scope probe picks it up very well also.. it is rather difficult to ** NOT** pick it up.

Suppose you can finally pick it up (easy!!!), then what do you want to do?
How relevant is seeing it on a scope? You know it's there sooo.....?

 

[ericgibbs]

hi hardwire,

Personally, I would not sit for long periods of time, close to [1mtr] a strong emf alternating source.

I would recommend that you google for emf radiation hazard research.

 

[Hardwire]

hi hardwire,

Personally, I would not sit for long periods of time, close to [1mtr] a strong emf alternating source.

I would recommend that you google for emf radiation hazard research.

Exactly. I suppose I should just move my work station without worrying about taking measurements... it's a huge power distribution unit so I'm sure there is something coming out of it.

The sensitive DMM's that I use pickup 60Hz quite nicely.. just need a big loop of wire, you can spot it easily.

usually an open scope probe picks it up very well also.. it is rather difficult to ** NOT** pick it up.

Suppose you can finally pick it up (easy!!!), then what do you want to do?
How relevant is seeing it on a scope? You know it's there sooo.....?

I'm an idiot! I didn't even think of that. Talk about over-engineering something that already has a simple solution! All you need to do is touch the tip of an oscope probe and your body works like a fine antenna for it. Must have seen it a thousand times but it didn't even occur to me.

I basically want to be able to quantify it rather than just know it's there. On a scope rather than a multimeter it will be easier to see.

 

[HiTech]

If you can withstand the crunching noise, wrap yourself with foil! Don't forget your head too.... that will protect you from alien mindreading should you ever have a close encounter of the third kind on your drive home from work.

Seriously, distance yourself from that unit. I've always pondered those HV tension distribution lines that wind their way through some housing developments. I couldn't imagine being an amateur radio operator and living next to set of kv powerlines!
I remember long ago of taking a shop job where the supervisor had me stationed in an equipment cage that housed a large power transformer w/ distribution panel and a monster air compressor as big as a pick up truck. Those two noise/heat/vibration soureces had be climbing walls (cage) daily. He claimed he had no other place for me in the machine shop, but it was a union place and I wasn't union so he may have done that to keep the troublemakers at rest. I lasted 2 weeks before taking a technician's position with Motorola.

 

[Hardwire]

Well I used myself as an antenna and I was able to pick up a bunch of 60 Hz EMF's around the lab. Surprisingly, the most potent sources were not the distribution panels, but the power strips under our desks!

Standing in the middle of the lab I was getting a pretty solid 1V p-p 60 Hz signal. Very smooth, too... almost perfect sinusoid.

Sitting at my desk I was receiving 5V, and just by moving my foot over the power strip as I sat there, I could get it to go up to 10V p-p.

Since the distribution panel is incased entirely in a metal box, I guess it's shielded pretty well (from EF at least... not sure about MF), but those darn power strips are quite "leaky".

I'm going to move my work station away from the panel anyway, and I guess I might as well distance myself from the power strip I use.

 

[Optikon]

Don't worry about 50/60HZ fields! You guys....

The scientific community is have a very difficult time proving that cell-phone GHz fields are harmful (and those have much more energy content) let alone worry about a lowly 50/60Hz field that relatively has no frequency content / energy. Want proof that it has no energy? Try and capture the field and power something with it to see. There is a *MUCH* larger risk of radiation from the sun by going outside when you leave work everyday.

High voltage is possibly a different story but you indicated 480V... that's nothing.

 

[Optikon]

Exactly. I suppose I should just move my work station without worrying about taking measurements... it's a huge power distribution unit so I'm sure there is something coming out of it.


I'm an idiot! I didn't even think of that. Talk about over-engineering something that already has a simple solution! All you need to do is touch the tip of an oscope probe and your body works like a fine antenna for it. Must have seen it a thousand times but it didn't even occur to me.

I basically want to be able to quantify it rather than just know it's there. On a scope rather than a multimeter it will be easier to see.

So you can pick it up to determine that it is present but I don't think you can quantify it easily. A loop of wire or scope input doesnt pickup the same amount the human body does necessarily. There are alot of variables to consider and most are not at all easy to control.

If you really must have a quantified answer (what would it mean anyways?) then you probably need to get ahold of a field strength meter that works down at 50/60Hz. But I would argue that you can't conclude anything from that number anyways other than it is non zero which, you already know.

 

[Hero999]

I wouldn't worry about being exposed to low frequency fields, I haven't found and solid evidence supporting the hypothesis that they're harmful to human health.

 

[TheVictim]

People have been living in the midst of HUGE 60hz AC fields for about a century now, and lifespans keep getting longer.

It could be that we no longer eat donuts fried in pork fat and wash them down with pond water, but either way it doesn't seem to be a big detriment to our health.

 

[RadioCrack]

I dont know if this will be of any help, but here is a simple circuit i found.