Grounding in patient care areas

[dcv]

I'm do a ground test in patient care areas, (patient vicinity)between a reference point and any exposed conductive sufaces and receptacles grounds.I'm using a fluke 87 trying to reach a resolution of 20%. Less 20 m Vrs + or - 4 mV into 1000 ohms and less than 0.1 ohms + OR - 0.02 ohms.
The readings I'm getting are between 16.0 and 19.0 on millivolt ac and .01 to .03 on resistance
leads are factored out grounds are tight, reference point is a cold water pipe and panels are bonded together as per NEC 517-14 thinking a more sensitive meter may do a better job any professional input would help. thank you dcv

 

[dereckbc]

Re: Grounding in patient care areas

For low resistance readings I would not be using a DVM. I would be using a Digital Low Resistance Ohm-meter (DLRO).

 

[dcv]

Re: Grounding in patient care areas

Thank you for your quick responses Dereckbc! can you recommend a meter?

 

[dereckbc]

Re: Grounding in patient care areas

Yes, http://www.qualityinstrumentsinc.com/products/biddle/dlro10.html

 

[brentp]

Re: Grounding in patient care areas

Can anyone else expound on this topic as I am also required to do this 'grounding' test as required by the Texas Department of Health? Do any other state health departments require this test? If so, how do you conduct the test and with what test instrument?

 

[Guest]

Re: Grounding in patient care areas

Type in "Diagnostic equipment grounding". Hit go! There are a few good sites.

 

[Guest]

Re: Grounding in patient care areas

I am starting radiation therapy and chemotherapy, in two days. I will pump the technicians for information on the test procedure.

 

[roger]

Re: Grounding in patient care areas

Brent, along with Bennie's suggestion you can go here.

Our test set is made by Bio Tek which has been bought by Fluke Biomedical.

The actual criteria for these test are in NFPA 99 chapter 4.

Roger

 

[brentp]

Re: Grounding in patient care areas

I've read many of your posts Bennie and have enjoyed them all! You really know how to make a man just THINK! I sincerely hope all goes well with your medical condition.

Brent

 

[brentp]

Re: Grounding in patient care areas

NFPA 99 chapter 4.


Cool!

 

[roger]

Re: Grounding in patient care areas

Bennie, I hope all goes well today.

Roger

 

[karl riley]

Re: Grounding in patient care areas

dcv, I returned my Fluke 87 when I found that it did not measure AC millivolts with any accuracy under about 20 - 30 mV. It is a design flaw (IMO) due to an evident attempt to beef up the bottom of the scale to overcome drop off. Didn't work.

Many cheaper dvms are accurate down to 1 mV AC.

Karl

 

[dcv]

Re: Grounding in patient care areas

Karl, I too have lost faith in my 87, I am now on a constant search from website to website,I want to find the most accurate meter I can,I need a handheld ,but I think the accuracy I'm looking for will be in a benchmeter with continious ac power source not a battery.I would be greatful for any help .
Thanks dcv

 

[tom baker]

Re: Grounding in patient care areas

dcv I have a fluke process calibrator, its acurate to a microamp. The display has three digits past the decimal but its micro or 10 -6. but it costs $5,000.
I also have a scopemeter by fluke I forgot the number 840 or something. Its an oscope designed for electricians, pretty nice with frequency and such to have the display, and it graphs.
Interesting about the low end inaccuracy on the flukes, what do they have to say about it?

 

[dcv]

Re: Grounding in patient care areas

Thanks Tom ,It sure would be nice to be able to use your calibrator ,but I don't think my company will spend the money ,very interested in the scopemeter I have not checked on this type meter can you tell me more, I will start researching them as well.
Derekbc gave me a website with some promising meters so for these meters have the best specs I've seen,but they too have a large price tag. If I am to get the correct reading I need for TDH my company will just have to pay.I just want to make sure I get them the best for their dallor.

I have not talk with Fluke about this meter's (fluke 87) inaccuracy, I believe the spec's show within .25%
I have heard bad stories about Fluke meters before ,but I still like their products.
I believe also the meter is about 6 years old.
I will send Fluke an email.
Thank again
DCV

 

[roger]

Re: Grounding in patient care areas

Did you check the link I provided, this branch of Fluke is specialized for what you are after.

http://www.flukebiomedical.com/

You can also contact Square D for their test equipment, but be prepared for a $7,000.00 price tag.


If your company is not prepared to pay above $2000.00, your State AHJ may not accept the results.

Roger

[ April 10, 2004, 07:46 PM: Message edited by: roger ]

 

[dcv]

Re: Grounding in patient care areas

Thank Roger I'll go there now.

 

[steve66]

Re: Grounding in patient care areas

Your low end inaccuracy of your fluke may be caused by its high imput impedence. High impedence is usually desirable in a voltmeter to prevent loading a circuit. But, high input impedence also increases the ability to pick up noise. If you are trying to measure the voltage on a 20' piece of wire that goes across a room, and you stretch the leads of the meter apart, you are actually creating a loop that can act like an antenna. A cheaper meter creates a lower impedence loop, which tends to reduce the voltage created by a noise current.

Steve