Grounding, Bonding, Solvent mixing

Aaaaaaaaaaaargh!!!

There is no such thing as 'explosion proof wiring'! The techniques used to ensure the safety of electrical circuits in potentially explosive atmospheres are outlined here:

http://en.wikipedia.org/wiki/Electrical_Equipment_in_Hazardous_Areas

<...The ceiling is designed to blow up and out for safety...>

This is not required by any code, and may invoke an additional hazard to those outside the room. Any potentially explosive atmosphere within the room needs to be small, an abnormal occurrence, and of short duration, and would result in an electrical classification of Zone 2. If it results otherwise, i.e. Zone 1, then there is a containment problem, and please be advised that the Health & Safety Executive has been known to invoke prosecution proceedings in the UK for an employer allowing staff to be present within those Zone 1s: "a flammable gas/air mixture is present under normal operations for short durations". This is the sort of thing that would blow the roof off, and, potentially, kill room occupants and passers-by. Alarm bells are ringing loudly in this part of the world.

<...I hope I am not missing something....>

This area of work does not embrace the luxury of hope! It is highly advisable to consult an experienced Electrical Engineer locally at the earliest opportunity to assess whether the installation is up-to-code and make appropriate adjustments to bring it to that point.

<...How do I size the [ground/earth] wire for the room or where can I find the appropriate information....>

The Institution of Electrical Engineers publishes and maintains the Wiring Regulations. Full guidance can be found within its pages. Any equipotential ground/earth conductor will have a cross-sectional area certainly no smaller than the largest conductor of any circuit feeding the room. Local standards and the desire for sufficient mechanical strength may impose more stringent requirements that involve fitting bigger conductors. Are these standards not to hand (good grief!) for guidance?

<....Additionally I currently have a lot of excess copper piping that I could use as a conductor or can I use a water line that I have grounded to our existing grounding system....>

There are now a lot of safety alarm bells going off in this part of the world! It would be highly advisable to consult an apprpriately-experienced Electrical Engineer at the earliest opportunity to assess whether the installation is up-to-code.

<...Copper buss bars are very expensive....>

The risks and costs of defending personal and corporate prosecution, loss of production from the demolished facility, the costs of reinstatement of the facility and the costs of compensations to persons affected by disregarding correct installation practice in this room would far outweigh the cost of a few metres of copper and the time taken to produce an installation that is up-to-code!

<...Any help is appreciated I have a February deadline....>

To do what? To complete an installation that is inherently capable of causing an explosion and killing someone?

Appropriate local technical advice is needed TODAY!

I second everything PW has written.

I used to live not far from a pharma plant that made syringes and had an accumulation of dust from polyethylene anti-stick agent. The plant, much cleaner than many, blew up from this dust in aerosol form. A roof that blows up and out is no protection.

I assume you are providing controls for static discharges, and are not venting the VOCs from this operation to atmosphere.

Unless you have a strong desire to make national news, this is the kind of installation that should be designed by someone with extensive experience in the safety and environmental issues involved.

WOW, I cannot believe that you would attempt to design something so dangerous. I agree with the previous poster because MOST everybody is not capable to design such an area. YOU CANNOT DO SUCH A TASK ON THE CHEAP, nor can it be done in a few days.

I would also like to add that you should seek the assistance of a well qualified electrical contractor (one that specializes in Hazardous Areas). Having worked in a project management capacity I have come to realize that although most Licensed Engineers are quite brilliant, they are lacking in extensive electrical code knowledge (this statement may not be true of Engineers worldwide, but it seems true in Sacramento California).

You cannot purge electrical boxes with air in lieu of using the proper explosion proof fittings.