240 panel fed by 480

[rt66electric]

I was asked to bid on adding an additional 3p circuit to panel. I found a 240v 3ph panel box and breakers being fed by a 100a 480v 3ph

It was a mismashed area some new eqiupment and some old. This sub-sub panel is fed by a 100a breaker off a federalpacific sub panel.

The incoming wireing consists of 1 1/2 EMT w/ (3) #2 maybe #4 AWG TW conductors without a ground conductor. The conduit/j-box also carries a set of (3) #10 condutors feeding a nearby disconnect.

This Is a power only panel no neutral


If I replace the panel should I ??

A- replace all of the conductors and add a green wire?

B- replace the panel useing existing conductors and call it good??

C- replace the panel useing existing conductorsand add a supplementary ground wire to overhead building steel??


My bid is competing w/" Mr. lowball bare minimum, its working long enough to get my check"

Management is aware of "Safety Hazard" ,but will look at numbers. If apples are cheaper than oranges, they will take the apples.

It is difficult to convince mgmt that added price to do the job correctly is necessary , as opposed to the "I can replace it with a new shiny panel price"

 

[growler]

It is difficult to convince mgmt that added price to do the job correctly is necessary.

That's where our friend the electrical inspector comes in handy, we don't really have much choice.

Could you run those #10's in a sepertate conduit without to much trouble? That would keep from having to derate the #2's. Then you could use a bond bushing for the ground if the EMT is in good shape. Make sure you bond the panel. And install a 480V panel. With the correct breakers.

Now you are set to install this new circuit.

 

[Chamuit]

Do it right.

It's your reputation, your lincense, your insurance, and your aft.

Lost a job the other to an Illegal alien. Can't beat $4 per hour and extension cords. (Yep, extension cord for 20 amp circuit.)

 

[zappy]

Do it right.

It's your reputation, your lincense, your insurance, and your aft.

Lost a job the other to an Illegal alien. Can't beat $4 per hour and extension cords. (Yep, extension cord for 20 amp circuit.)

LOL. I would love to see a pic of that job.

 

[rt66electric]

I amazed that it has't blown up

I amazed that it has't blown up

How many of you have seen 240breakers / last on 480 circuits??
These breakers appear to be used regulary for LOTO procedures.

I would say the panel is atleast 15-20 years old. It is a standard cutler hammer BR push-in with copper buss.

 

[LarryFine]

LOL. I would love to see a pic of that job.

As Judge Haller said in My Cousin Vinny: "So would I!"

 

[Chamuit]

I have seen 277 n 480 V breakers used on jobs because of rating issues. I must say I haven't ever seen it the other way.

As for pictures of the extension cord, my son was using (read: playing with) my job site camera and ran the battery out. Ugh! I need to invest in a rechargeable battery.

 

[Chamuit]

I have seen 277 n 480 V breakers used on jobs because of rating issues.

277 and 480 bolt-ons in 120/240 applications.

 

[Derick]

LOL. I would love to see a pic of that job.

Looks like this:

You hold the wall I go get the money

 

[tryinghard]

Sounds like design build type work; give at least two price options and scopes, minimum and whatever. Be clear in your scopes siting NEC throughout. Follow up call the client after sending your bid proposal review and stress compliance by explaining code compliant means specifically/only personal and property protection, and non-compliance encourages electrocution and fire danger meaning it would be electically unsafe.

 

[danickstr]

while on this topic, I had read that a "slash rating" breaker cannot be used on ungrounded systems. Can someone confirm this?

 

[SG-1]

So long as the lower voltage rating on the breaker is equal to the ungrounded L-L system voltage it could be used. For instance if the system is 240 and the breaker reads 480/277, then it could be used. If the lower number is 120 it cannot be trusted to clear a fault at the higher voltage. This type of breaker receives it's interrupting rating from the L-G voltage rating printed on the label.