magnetic fields and prosthetic devices

fgr@st-andrews.ac.uk
Thu, 6 Oct 1994 16:58:19 +0000

We have had an incident that may have been caused by the stray field from
our MSL 500 magnet. A student passed about 16 metres away from our MSL
500 magnet this afternoon and her prosthetic pain killing device that works
on the same principle as a heart pacemaker was switched off. The wide
bore 500 magnet does have an enormous stray field which is greater in the
vertical than the horizontal direction. My estimate based on data
supplied by Bruker is that she could only have experienced a maximum field
of 1 gauss. On the other hand the device has never switched itself off
before, so we are working on the assumption that it was the stray field
that caused the incident.

This incident emphasises the importance of visible warning notices and
careful instructions to janitorial staff concerning the possibility of such
events. We have such notices at the entrances to our building but this
did not stop the incident!

Thank goodness it was not a heart pacemaker!!!

Frank Riddell