Sizing Equipment

Status
Not open for further replies.
E

Eli1211

Member
Location
Wisconsin
Occupation
Electrician
I have a job a could use a little advice/reassurance on. It is a commercial space, a granite company. They are installing a new piece of equipment for cutting granite. The only electrical information provided by the manufacturer of this equipment is the following:

There are 2 required power hookups to the TITAN with

the requirements as listed below:

NOTE: Power run must be completed by a licensed electrician.
TITAN Electric Requirements
480 VAC (+/-10%), 3 phase, 60 Hz, 30.0 Full Load Amps
(A 60 amp thermal-magnetic main breaker is factory installed inside the electrical enclosure)
OH Laser Electric Requirements
Standard 120 VAC 15 amp electrical outlet
(Outlet MUST be within 25’ of the laser post location, refer to the installation
drawing for details)

Sizing equipment like this needless to say is not my bread and butter. However, from what I remember and what I have looked up. The equipment is not to be sized off of the nameplate rating but rather the HP/FLC using table 430.250. I would multiply the FLC by 125% which would give me my wire size. Then use the FLC found on table 430.250 and reference table 430.52 to get my breaker size. Table 250.122 for equipment grounding conductor size.

Am I right to say I need more info? Like the HP of the motor, motor type?
When should a fused disconnect be used over a non fused disconnect for something like this?

Any help would be much appreciated.
 
Are you able to explain further? I am a small electrical contractor. We do mostly residential/light commercial service work. I also do restoration electrical for some restoration contractors in the area. This is outside of my day to day and just looking for a little understanding.

Wire size, breaker size, disconnect size, all of it is based off the 30 full load amps?
When would a fuse disconnect be used over a non fused? Would that just be a specific piece of equipment or manufacturer recommendation type of thing?
 
Look at it this way. The thing says 30 amps flc. So ampacity has to be a little more. So it can't be any smaller than #8 anyway. Short of vd considerations or conductor derating it would not have to be bigger than #8 either.
 
petersonra said:
Look at it this way. The thing says 30 amps flc. So ampacity has to be a little more. So it can't be any smaller than #8 anyway. Short of vd considerations or conductor derating it would not have to be bigger than #8 either.
Click to expand...
I was to thinking the same thing but if this is not a continuous load could it be supplied by a 30 amp circuit?
 
infinity said:
I was to thinking the same thing but if this is not a continuous load could it be supplied by a 30 amp circuit?
Click to expand...
There is a paragraph in the code that describes the minimum feeder ocpd rating. I don't think you would be able to do a 30 a circuit for a 30 a load that has any motor in it.
 
petersonra said:
There is a paragraph in the code that describes the minimum feeder ocpd rating. I don't think you would be able to do a 30 a circuit for a 30 a load that has any motor in it.
Click to expand...
But this is an individual branch circuit. Wouldn't 210.22 allow it to be on a 30 amp circuit?

210.22 Permissible Loads, Individual Branch Circuits. An individual branch circuit shall be permitted to supply any load for which it is rated, but in no case shall the load exceed the branch-circuit ampere rating.
Click to expand...
 
That was my thinking. Feeder circuit for at least one, potentially multiple motors. Wouldn’t I figure it as stated in my initial post? Obviously, if multiple motors, the first one at 125% and subsequent motors at 100%.
 
I no longer need any help. Thanks for everyone who chimed in. A previous foreman of mine who has over 40 years in the trade got back to me and was able to spell it out for me. Thanks again.
 
petersonra said:
the OP said it has a 60 Amp CB in the equipment. That makes incoming power a feeder circuit.
Click to expand...
An OCPD at the equipment does not automatically make it a feeder it could be supplementary overcurrent protection as outlined in 240.10 but even if it is a feeder isn't a feeder calculated at 100% of the non-continuous load?

Eli1211 said:
I no longer need any help. Thanks for everyone who chimed in. A previous foreman of mine who has over 40 years in the trade got back to me and was able to spell it out for me. Thanks again.
Click to expand...
Well what did he say?
 
Feed the main breaker that is factory installed in the electrical enclosure attached to the equipment. All of the sizing of motors and everything has already been done by the manufacturer. Just need to feed the main breaker. Do not even need a disconnect, as there is the main.
 
Status
Not open for further replies.
Top