Bus Plug Fusing... 1

[cfordyce]

Currently I have a 600V Westinghouse Bus Duct in a particular area of the plant. One 200A rated, 150A fused bus plug feeds two identical pieces of equipment. The majority of the equipment load is a 40hp motor in each machine. The protection at the machine is either a 60A time delay fuse or a 100A breaker (it varies by machine). Does this pairing of loads on one bus plug break any code requirements? I am in Ontario but if this is a problem, I would think it would be anywhere. Thanks.

CAF

 

[briand2]

CAF,

I can't see any problem, as long as each cable from the bus plug is suitable protected by the 150A fuse. The fact that each machine then has a smaller fuse (60A or 100A) means that if that blows, the other machine is left unaffected. Obviously I haven't done any calculations for this, but in principle is is totally acceptable.

Brian

 

[briand2]

CAF,

Sorry, I forgot to mention; I practise in the UK, not Ontario!

Brian

 

[alehman]

What you describe would be acceptable by the U.S. National Electrical Code.

 

[jbartos]

Suggestion: One concern is around safety code another may be around the industry standard practices. For example, short circuit current contributions by motors tend to be more on the industry standard side. If overlooked, they can cause the switching equipment to malfunction. The safety code would focus more on minimum conductor sizes, equipment minimal safety, personnel minimum safety, etc.