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Re: Faricating Guards out if Lexan? [Re: frank] #217946 01/14/17 11:09 PM
Joined: Jul 2002
Posts: 8,262
Trumpy Offline
Member
Frank,
I may be wrong here, but is Lexan self-extinguishing if it catches fire?
Also, what are the temperature limits of this material, if it is anything like Plexiglass, it softens when you heat it up, that's how they form it to build things out of it.
What I'm trying to say here is that while there shouldn't really be a lot of heat in any electrical enclosure, but that needs to be taken into account if you are using thermo-setting plastics.
Just a thought off the top of my head.

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Re: Faricating Guards out if Lexan? [Re: frank] #217956 01/16/17 08:33 PM
Joined: May 2001
Posts: 376
F
frank Offline OP
Member
Trumpy,
The numbers are all over the place.Thermal resistance is 250F and dialectic strength is 400 ohm cm.It is self extinguishing but thats from one of many data sheets the numbers are relative to the particular manufacture.

My concerns are.

-Added electrical component heating

-How it will react in an arc flash/blast situation

-how do you mount/form it in the tub and whats required clearance from the energized parts.

- will it attract dust,filings,and fluff over time

-is it going to rattle apart around equipment such as high cycling starters.

-will this affect the equipment CSA listing as its an improvised alteration and not manufacture approved.

-Liability in the even of an accident investigation.

The main concern is that after talking to many electricians no one has thought of or attempted fitting unapproved guarding in such a way.
Any guarding that is an original equipment part has been engineered and tested to a set standard.Once CSA has approved and listed it further modification is asking for trouble.
I also don't understand the point.It will create an obstruction when making a visual inspection,trap any garbage that falls between it and the fusing OR buss,obstruct air flow and heat dissipation.It will have to be removed in order to troubleshoot and re torque screws which i normally do on all equipment that i work on.
To me this seems like a bad idea.Am i missing something?
Thanks





Last edited by frank; 01/16/17 08:38 PM.
Re: Fabricating Guards out of Lexan? [Re: frank] #217963 01/17/17 04:36 AM
Joined: Jul 2002
Posts: 8,262
Trumpy Offline
Member
Frank,
Your concerns are not un-warranted either, as you've mentioned yourself, this whole thing involves the installation of unapproved modifications to this equipment.
In saying that though, we use clear plexi-glass covers held in place with insulated studs on a DIN Rail and these have a heap of holes for getting test probes in to fault-find equipment and this also ensures adequate air circulation.
Having things fall into the live busbars or other equipment is not really an issue, because of the way the shields are formed, they have a 45 degree angle at the top and bottom of the part that is held to the studs.

Re: Fabricating Guards out of Lexan? [Re: frank] #217970 01/17/17 03:21 PM
Joined: May 2005
Posts: 984
G
ghost307 Offline
Member
I wouldn't worry too much about getting hit with the makeshift plexiglass cover...melted or not.

The initial blast will probably kill you if you're not wearing the proper PPE.


Ghost307
Re: Fabricating Guards out of Lexan? [Re: frank] #217983 01/17/17 07:24 PM
Joined: May 2001
Posts: 376
F
frank Offline OP
Member
Ghost,
This is true but i just find it insulting to be asked to add shrapnel to my own IED.I told him to go look at the videos and he just stood there and blinked at me like he usually does.No matter i told him to stick it......not doing it....ever.

Re: Fabricating Guards out of Lexan? [Re: frank] #217984 01/17/17 08:11 PM
Joined: May 2001
Posts: 376
F
frank Offline OP
Member
Trumpy,
These are older 600v 40hp starter buckets that are also populated with extra low voltage automation.The fusing and O/L'S are brought to as close to FLA as possible on the inspectors orders to get special permission.Heat can be and has been an issue.
The fuse holders stand 8 inches tall on idolators and they do not have a molded base that extends out past them that would act as a stand off.There is also little room if any for mounting the lexan and the starters are even worse.This is nothing like covering Din rail mounted terminal strips to which i see the logic.If i could post a picture i would.

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