brother

I know theres no 'code' issues here that I can think of (NFPA 79 maybe?), but I don't think this is common practice, at least I have not seen it done this way.

Theres this control cabinet (that controls 3 motors) that was not wired correctly, the 'run' indication lights are wired in parallel with each motors disco. Basically, you can turn off disco 1 and leave at least one other disco on (2 or 3) and turn the 'hand off auto' of motor 1 to the hand position and the run light will come on, showing that motor 1 is running, but in reality its not.

The controls are 120v (including the lights), which is normal, the motors run off of 3 phase 480. I suggested to a guy to correct this issue he just use some auxilary contacts on the each contactor and wire the indication lights off of them, so when that particular motor contactor is closed, the the lights will come on only at that time.

He wants to run '480 volt' to the indication lights off of the load side of the contactor (the t1, t2, t3 leads to the motor), basically just tapping off of them that way. He has to special order these '480' lights. Apparently he feels this will give 'true' indication. Would you wire it this way, or the way I suggested seeing that the 120 is already there from the transformer.???? 120 and below has always been for controls in my experience, including the lights.

Jlarson

What did the guy "learn" how to do controls from a book he got out of a box of crackerjacks?

So is it one one common 120v control supply? Is that tapped off one of the 3 discos?

__________________
The best never stop learning.

erics37

And it will be wired ridiculously if he does that. Either way (his or yours), he's going to have to order something. Might as well order some quick-n-easy auxiliary contacts for the starters instead of some 480 lights for the control panel. Guy sounds like a douche lord.

If I can avoid wiring something 480, I will. I wouldn't want to be working in that panel, expecting everything to be 120, and then run across something like that. Especially if they're not fused down from the tap.

__________________
- Eric

brother

Crackerjacks?? LOL haven't heard that used in a while. yes there is one 120 supply, thats tapped off the main lines(480) comming in basically the 480-120 transformer is parallel with the discos.

I just dont see why he would want to go this route, but oh well, it all pays the same.

MDShunk

There's a few ways to do this, but for the most part, there are already contacts on the motor starter used for this purpose. That said, you can still turn off the feed to the motor (480) and leave the control power on and have the light illuminate. That would be considered normal operation, even if the lamp isn't a true indication of the motor running status in that case.

__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.

Jlarson

I have no problem with 480 controls, you shouldn't go around assuming everything is going to be a certain way anyway IMPO, that's how accidents and mistakes happen.

__________________
The best never stop learning.

MDShunk

Yeah, but he's talkng about 480 volt indicator lamps. That is a bit on the odd side of things. Let some guy try to put in an ordinary 755 lamp, and ka-boom!

__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.

Jlarson

Sounds like aux would be the easiest and lowest cost route. Like MD said it won't really be a true indication unless you get fancy and throw in current switches, relays off the load side of the discos to cut control power to that starter or make each starter's control power independent of the others.

__________________
The best never stop learning.

Jlarson

Odd must be a way of life for me then.

I personally try to avoid anything but 120 control on new work just cause the options for stuff are wider but sometimes you got to work with what ya got.

__________________
The best never stop learning.

MDShunk

Would I wire it that way? You bet... whatever he wants to pay for, but I would push for transformer type lampholders and not 480 volt lampholders for safety's sake. For instance, you can get Allen Bradley Bulletin 800 lampholders with transformer bases for any voltage up to 600V, and it still takes a 757 lamp.

__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.

brother

I cannot remember where I read it but I thought there were new codes that wanted new controls at 120 or lower, this helps easier compliance with NFPA 70e when trouble shooting.

Jlarson

I think your best bet for a "real" indication without making any real changes in the control is to put the lamps across the load side of each starter. With them placed there they wouldn't indicate with the disco off.

Preferably you would use the xformer type pilot light though, like Marc said.

__________________
The best never stop learning.

miller_elex

Yeah I like the 480V idea, but think about this:

277V.

Drive a tech screw into the back of the can, then run a white wire to the tech screw from the 277V lamp.

Now you don't have to go leg to leg 480V. Just hit the A-phase and call it good

miller_elex

Don't feel bad Brother,

RUN light Malfunctions are on every punchlist, every job.

Jlarson

At least have some pride in your hackery and drill and tap instead of using a tec screw.

__________________
The best never stop learning.

mcclary's electrical

Let's hope you're not serious

John Valdes

Use the auxiliary contacts from each contactor. That's how its done. If there is no aux. left, get some more. If you need a proving circuit, whats the application. Just because you have 460 at the load side of the contactor, does not mean the motor is running.

miller_elex

Honestly, if its critical, I'd go with a $30 Hawkeye 800 for the RUN status. That $30 current sw will save you all that time it takes to rip it all out and redo it right. You'll have to check the rating on the current sw, I was using them for DDC.

brother

Actually, its really NOT that critical to see the 'LIGHT' running because the motor is right there not even 3 ft away LOL. I just wanted to be sure I wasn't thinking wrong on this. Basically a simple aux contact would be best here and quick and easy.

I dont like 480 on the doors either, but on VERY rare occansions on OLD systems Ive seen it, and most guys change it to 120 or less.

brother

Ok, I found the code or standard I was looking for. IT was 2007 NFPA 79 Electrical Standards for Industrial Machinery like I had thought

2007 NFPA 79 9.1.2.1 AC Control Voltages.
"The AC voltage for control circutis shall not exceed 120 volts, AC single phase. "

So I can tell him he can NOT wire it that way, I'll try to bluff him, because I'm not sure if my area has adopted this standard or not

So therefore MDSHUNK you cannot wire it that way either, no matter what they ask for.