Um, Triacs and other semiconductors usually fail "closed". That is, the
circuit is "closed" such that it conducts current. Resistive elements on
the other hand generally fail "open" such that current ceases to flow.

Dave Lane
Principal
Clavis Technology Development

On 9/21/20 10:37 AM, Chantal, Pierre (HC/SC) wrote:
> Hi,
> Two situations:
>
> 1.       Temperature controllers that are equipped with a “Triac” are likely to create problems because if the “Triac” fail it will put the controller in full open position thus generating problems.
>
> 2.       Do not connect a variable transformer to a temperature controller… this will also create problems to your controller.
> Hope this help
>
> From: ACS Division of Chemical Health and Safety <DCHAS-L@Princeton.EDU> On Behalf Of Samuella Sigmann
> Sent: 2020-09-21 12:34 PM
> To: DCHAS-L@Princeton.EDU
> Subject: [DCHAS-L] Website Updates - Electrical Safety Alert - Followup
>
> All -
>
> Just as a followup to this information, we pulled 12 controllers from our Organic lab rooms last week. Seems to be a real issue with heating mantle controllers.
> Sammye
>
> --
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> Non-Tenure Track Faculty – Qualified to cook the meals and wash the dishes, but not eat at the table.
>
> Samuella B. Sigmann, MS, NRCC-CHO
> Immediate Past Chair, ACS Division of Chemical Health & Safety<https://dchas.org/>, 2020
> Senior Lecturer/Safety Committee Chair/Director of Stockroom
> Chemistry
> Appalachian State University
> 525 Rivers Street
> Boone, NC 28608
> Phone: 828 262 2755
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> Email: sigmannsb@appstate.edu<mailto:sigmannsb@appstate.edu>
>
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