Laser equipment installation.

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AJones

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Location
Houston Texas
Occupation
Maintenace Electrician
I have been provided the following information on a laser machine 208V 3P+10%-5% 42KVA 122FLA
208V 3P+-10% 25KVA 72 FLA
I have an empty 225A 3P panel with existing conduit runs that land near where the equipment will be installed.
My plan was to utilize this existing panel and add a 120A 3P and a 70A 3P bolt in breaker to energize these branch circuits, terminate to a
disconnect for each one and then fuse with 150A and 90A fuses and then drop to each location. I feel as if I am missing something any
ideas? All other equipment installed currently is 460/480 3phase and we have no issues. I have not installed any 208 equipment other than welders
in this shop.
 
If the CBs are truely "near" where the equipment is, why do you need disconnect switches?

I have been provided the following information on a laser machine 208V 3P+10%-5% 42KVA 122FLA

208V 3P+-10% 25KVA 72 FLA

I have an empty 225A 3P panel with existing conduit runs that land near where the equipment will be installed.

My plan was to utilize this existing panel and add a 120A 3P and a 70A 3P
Click to expand...

Seems to me that the CB ratings are a bit on the light side. I'd be looking at maybe 175 and 100 Amp CBs, respectively, depending of course on the manufacturer's suggestions.
 
petersonra said:
If the CBs are truely "near" where the equipment is, why do you need disconnect switches?



Seems to me that the CB ratings are a bit on the light side. I'd be looking at maybe 175 and 100 Amp CBs, respectively, depending of course on the manufacturer's suggestions.
Click to expand...
Actually the panel is not close to the equipment. Existing pipe runs happen to be where the equipment will be installed. The panel is over 100' away. As for the panel itself it is a Square D 225A 208 3P NQ43OL2C I'm not sure I can get a 175A breaker to fit this enclose. That being the case
my next option would be to feed it from a 3P/480V panel to a step down transformer and a gutter. I just wished they stayed consistent with 480V through out this shop but this machine only comes in 208V.
 
If you can't get an adequate sized breaker maybe you can get feedthru lugs and just run a feeder out to the two fused disconnects you want to add.
 
petersonra said:
If you can't get an adequate sized breaker maybe you can get feedthru lugs and just run a feeder out to the two fused disconnects you want to add.
Click to expand...
Agreed again. If the conduit size allows, a single 225a feeder to the loads should be cheaper, and tap rules should let you feed the two fused disconnects directly.
 
I have 2 empty runs of 1 1/2" EMT to a pull box above the area where the disconnects will be mounted from the panel. At 225A that would require
4/0 x 3 with a #2G minimum conduit size would be 2" so I guess I'm sol unless the provider of the equipment could assure me otherwise.
If only this were 480V...
 
AJones said:
I have 2 empty runs of 1 1/2" EMT to a pull box above the area where the disconnects will be mounted from the panel. At 225A that would require
4/0 x 3 with a #2G minimum conduit size would be 2" so I guess I'm sol unless the provider of the equipment could assure me otherwise.
If only this were 480V...
Click to expand...

For 225A, you could run a set of #1 in each pipe. And with EMT, a separate EGC isn’t necessarily required.
 
2 double barrel feed through lugs would be a lot more cost efficient than re-running conduit etc. If the management is okay with this
that may be my best approach. Thanks.
 
I know it's not the same thing, but in 1987 or 1988 I was fortunate enough to see Blue Oyster Cult's laser light show that was drastically cut back after 3 or 4 performances. While it was running a fire department pumper truck was parked outside the venue supplying the water needed to cool the gear powering the lighting equipment with the understanding that if a fire broke out somewhere nearby they would have to shut the lasers down. It was an amazing show; I have never seen anything else remotely like it.
 
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