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Phil, Mechanical Engineer
Category: Electrical
Satisfied Customers: 8429
Experience:  Retired electrical contractor, 51 years experience.
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I have an outlet 3 phase that is reading 108 on two legs and

Customer Question

I have an outlet 3 phase that is reading 108 on two legs and 208 on the other leg. And showing no power at the unit is supposed to operate could it be that the breaker is bad
Submitted: 8 months ago.
Category: Electrical
Expert:  Phil replied 8 months ago.

Hello, on three phase systems, two of the legs will read 110v (approx) to ground and one of the legs will read 220 volts or a bit higher to ground...that is called the 'high leg' or the 'stinger' generally.

You should read 220v approx across all three combinations including the stinger however.

Check that at the 3 phase breaker, if you have those readings there, the problem is closer to the unit you are powering, perhaps a blown fuse in one or two of the legs, or a bad magnetic starter on the motor (try pressing its reset button)... and check power across L1,L2, and L3 at the line side of the magnetic starter (if its a motor).

We can go from there

Customer: replied 8 months ago.
I will try that today and get back to you. This outlet powers a flat top griddle in a restaurant. The readings I got were from the outlet itself.
Expert:  Phil replied 8 months ago.

OK, I will be here all day.

Customer: replied 8 months ago.
The three legs coming out of the breaker all show 208 in any combination. I do not have that at the outlet the powers The Griddle
Expert:  Phil replied 8 months ago.

Thanks, ***** ***** have no power at all across any of the outlet terminals, then it is most likely that you are on the wrong 3 phase breaker or there is a disconnect switch between the griddle outlet and the breaker.

IF you have some power across any two terminals at the griddle outlet then there is a bad wire somewhere between the breaker and the outlet.... sometimes junction boxes with splices in them get hidden, sometimes inside a wall.

I need to know in detail what sort of voltage, if any, you are getting at the griddle outlet.

Customer: replied 8 months ago.
I took the outlet off the wall and tested all three legs and now they're working I don't understand it unless I had a loose wire and I did not discover that
Expert:  Phil replied 8 months ago.

It is hard to get good contact with meter probes in some receptacles, does the griddle work now?

Customer: replied 8 months ago.
I had no power before
Customer: replied 8 months ago.
Understand that the grill would not heat up and the power indicator lights didn't come on.
Expert:  Phil replied 8 months ago.

Sometimes the prongs on the cord cap do not make good contact inside the and twist them slightly to fix that. Beyond that there would likely be burnt wire connections inside the griddle, often at the electric heating elements.

Customer: replied 8 months ago.
I'm familiar with the inside of the griddle. No marks like that. I always check the equipment first, after the breaker.
Expert:  Phil replied 8 months ago.

Let me know how it goes, if you have power to the receptacle you would have power to the griddle, assuming the prongs on the plug are making good contact.

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