ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
DIFFERENCE BETWEEN SCADA AND HMI: AUTOMATION ACRON
by niamishra. 10/16/18 07:18 AM
Tingle off the water spigot
by dsk. 10/15/18 02:36 PM
Board tester power supply?
by JoeTestingEngr. 10/13/18 12:14 AM
Voltage sag
by Trumpy. 10/12/18 06:59 PM
220/230/240V 60Hz Systems
by Trumpy. 10/12/18 06:50 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 13 guests, and 27 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
M.R.I. #55179
08/19/05 04:36 PM
08/19/05 04:36 PM
M
master66  Offline OP
Member
Joined: Apr 2002
Posts: 257
Masontown, PA, USA
An Electrical inspector friend of mine called me with some questions regarding MRI Rooms. I had no answers for him so I told him that I would ask you guys.

His questions were concerning the proper bonding required for the metal walls of a MRI room and he asked about some sort of isolation coupler shown on the plans (can't think of the name of it now).

Anyone here worked around MRIs? Would you describe the bonding requirements & what he should expect to come across?

Thanks in advance.
Brian

Work Gear for Electricians and the Trades
Re: M.R.I. #55180
08/19/05 06:43 PM
08/19/05 06:43 PM
R
Roger  Offline
Member
Joined: May 2002
Posts: 1,716
N.C.
Brian, check the link below for a short thread on this issue.
http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=007280#000001

Roger

[This message has been edited by Roger (edited 08-19-2005).]

Re: M.R.I. #55181
08/19/05 09:56 PM
08/19/05 09:56 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,034
Brick, NJ USA
Brian:
The grounding/bonding/shielding for all the MRI's we have been involved in is ALL within the MRI Mfg specifications, and is always stringient. The RF shielding is a single point ground on the outside of the RF room.

You probably are talking about RF filters, wich in our case are supplied by a RF contractor that is specified by the MRI Mfg.

We have installed Siemens and GE units, they are basically the same; very stringent specs.

John


John
Re: M.R.I. #55182
08/20/05 02:51 PM
08/20/05 02:51 PM
A
Alan Nadon  Offline
Member
Joined: Mar 2005
Posts: 399
Elkhart, IN. USA
I have inspected three MRIs in my area. I learned as I inspected and can say the last one was completely in compliance with the Code.
Biggest problem is that the MRI techs will insist that wiring be done in PVC because of the magnetic field. They ignore Section 517.13 that requires METAL conduit. They also think that individual conductors can be run from the ends of the PVC to the RF filters without being in conduit because the RFs are not supplied with any kind of connector for a raceway.
The last one I approved was done in ALUMINUM conduit with AL. boxes and fittings. The filters had threaded ends. Alum. flex over six feet does not comply.
This applies only to the wiring for the lights, recpts. etc. The feeder to the machine is allowed to be in PVC, because it is not a Branch Circuit.
The MRI Techs said they had never seen one in conduit before and they were installing them all over the country.
This is a patient care area.
The panels in the room were bonded with a copper mesh (for degaussing ?) and bonded to the building steel outside the room. The metal raceways also created a bond when fastened to the walls.
Remember NO PVC. 517.13.
Make sure the electrician, the inspector and the suppier of the MRI equipment TALK to each other before it becomes an expensive change or a non-complying installation.
Alan--Inspector.
I believe Stainless Steel is also acceptable in a magnetic field but, that needs to be checked out. Good Luck.



[This message has been edited by Alan Nadon (edited 08-20-2005).]


Alan--
If it was easy, anyone could do it.
Re: M.R.I. #55183
08/20/05 03:38 PM
08/20/05 03:38 PM
R
Roger  Offline
Member
Joined: May 2002
Posts: 1,716
N.C.
Alan, Aluminum, Copper, or Steel, can all be used for the shielding envelope.

The wiring method can be EMT,IMC,RMC,HCFC or aluminum within the walls, but is typically aluminum flex or MC above the ceiling.

There MUST, be a dielectric separation from the metallic raceways inside the room and the grounded raceways outside the room, we accomplish this with carflex from the filters to junction boxes for the building wiring servicing the room.

The single point ground bonds everything back together and to the buildings earth system at the RF filter location.

The redundant grounding per 517.13 will become common at the single point grounding provision.

In reality, it is a moot point because I have never heard of any patient being attached to electrical equipment while inside the room, much less the magnet.

The receptacles are many times outside the patient vicinity as defined in NFPA 99 and NEC article 517, this in itself changes the rules for the space as far as the room meeting other requirements of both codes.

I have even been involved in some MRI's with no receptacles in the magnet room at all, house keeping used receptacles immediately outside the space.

In the event of a Code Blue situation, the patient would be removed from the magnet room where the respondents would treat the patient, so there would be no need for receptacles in this space for that issue.


Roger


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Alan Belson
Alan Belson
Mayenne N. France
Posts: 1,803
Joined: March 2005
Show All Member Profiles 
Top Posters(30 Days)
sparky 11
Popular Topics(Views)
250,292 Are you busy
187,931 Re: Forum
177,465 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.022s Queries: 14 (0.003s) Memory: 0.9703 MB (Peak: 1.1096 MB) Zlib enabled. Server Time: 2018-10-16 12:25:48 UTC