I've done mostly residential work over the course of my career. New work, old work, service work, add-a-levels, additions, alterations, etc. I'm currently looking for a new job and I see a lot of people looking for help in the commercial field. So for a guy like me to make the leap from resi to commercial what would you suggest that I absolutely have to know in order to do commercial-type work?

1) Pipe bending
2) 480/277
3) Motor starters and controls
4) the machinery and the process
5) PLC's

1) All flavors of 3 phase
2) Industrial safety
3) Lighting

My pipe bending skills are minimal. I've taken the pipe bending course at Vo Tech but like most resi elec's we don't get to do much bending. I know all the multipliers and can bend 1/2" and 3/4" emt pretty good but the bigger benders I've never used on job sites.

I'm not totally unfamiliar with 3 phase.

Black, red, blue is normally a 120/208 Wye system with a grounded conductor
Black, red, blue can also be an open delta system where the 'wild leg' is 208 volts to ground should be phase 'B' indentified in orange
Brown, orange, yellow is a 277/480 volt wye system with a grounded conductor
277 volt is a single phase voltage
480 volt is either 2-pole, or 3-pole
3-phase motors have only run windings, no start windings
If a 3-phase motor is operating backwards, reverse two of the leads

PLC's I know nothing about.

Motor starters and controls I somewhat know

1) oddball breakers [ you will run into few of it ]

2) large number of MWBC's

3) large Distubation centre

4) MCC buckets

Say I had (3) 277 volt circuits and the load was 10, 4-lamp, 2x4 lay-in fluorescent light fixtures for each circuit, could I run a 12/4 MWBC and share the neutral for all three circuits?

yep you can do that that is very common on commercal area

Merci , Marc

I thought so.

just rember the golden rules with MWBC is that never take the neutral line off at all.

it happend to me few time when i was not carefull i have few 277v ballast went up smoke [and alot of french cussing with it ]

after that i got wise get ampmeter to read the amp load on netural to make sure it is safe but anytime you work on pretty large commercal area it can be pain in butt when you try turn off the lumiaires for mantaice work especally with ballast that will compound it.

i know one place they wont let me turn off the light when the ballast is burn out i told them sorry i want to turn it off when i work on it some case it take act of god to do it

Merci, Marc

• Fault-finding and Testing.
• PLC's and Industrial Sensors and their applications.
• Control systems used in processes and the processes themselves.
• Hand signals for cranes and other machinery used in factories while positioning equipment to be installed.

If you haven't got some already, get yourself a good set of 4 or 5 lock-dogs and padlocks to fit to breakers in factories, people have a habit of turning breakers back on if thier equipment fails to work, regardless of if it is the circuit you are working on.
Back that up with Red lock-out tags so that people know a qualified person has locked out the energy source and the breaker has not merely tripped.
One other aspect of this kind of work is the fact that there is a certain amount of pressure on you to get gear working again in as shorter time as possible, time truly is money when a factory is down and there are people standing around doing nothing, these people are still being paid.