Monday, January 19, 2009

General guidelines for high voltage area?

What is general guide lines for EPA area, where live AC and DC equipment is used?

If personnel are handling ESD sensitive devices, the general guidelines are the same as for any other ESD Protected Area. See my ESD Guide.

However where high voltages are present there may be a safety concern about earthing the body either through a wrist strap or through conductive footwear and flooring. In this case the risks must be evaluated and if necessary, the ESD precautions modified to reduce safety risks to an acceptable level.

Usually, wrist straps and footwear for ESD use have a minimum of 750k ohm resistance, which is designed to give some protction for up to 250Vac systems. For higher voltages higher resistance (pro rata) can be used if desired. If the risk of shock is unnacceptabe it may be necessary to avoid grounding personnel and use other ESD protection methods. There is no general advice on this as far as I am aware.


Diali said...
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Missies said...

Hi there, I work in an industrial environment and I have a bagger that has a chute made out of HDPE. We need to take chute down a lot for cleaning purposes ( food manufacturing), Our operators have been getting (static shocked) zapped by the chute ( while taking it down or when it is actually on the a cart). We have put a ground strap on the chute, it’s not really helping. Do you have an idea on what we could do to prevent this?

Thanks, I appreciate your help in advance.

Static Doctor said...

Probably the shocks are due to high levels of static charge built up on the chute. There are other possible mechanisms and factors though.

Grounding the HDPE will not drain the static away, as HDPE is an insulating material which does not encourage charge to move around.