A little off topic, but I know someone here will have the answer. I have a genset with a 220v recepticle which I wire into a transfer switch. The only circuit that actually uses 220 serves the well-pump. The transfer switch has a ganged 20amp breaker, which I wired to the well-pump circuit. The generator, however, has two 20amp pushbutton circuit breakers, one for each leg of 110. My question is: If one of the generator breakers tripped, then my well pump would be getting only one leg of 110. Would the increased load on the ganged breaker on the transfer switch cause it to also trip, or should I wire in a ganged breaker at the generator itself? I certainly don't want or have a way to test this...so I'm looking for advice. Thanks, Nok
If either breaker opens the well pump won't run. There would be a lower load on the generator, without the pump. The breaker that's going to trip is the one with an additional load, so you'll notice that the pump isn't running.
Not if both breakers are accurate. The well pump loads both sides, and one breaker by itself. The other breaker will have a higher load and should trip first, if the load is more than a few tens of mA. He could always add a small double pole breaker box and a 240 V 20A breaker like those for a pump or small A/C to get common trip. Connect it to the line side of the existing breakers.
Zowie! twice in one day, I'm agreeing with Stormin. The dual ganged breaker is there to ensure that if either side trips, that there is no power in the box. That's for the purpose of protecting the electrician, not the equipment.
I'd spend the money on a good GFCI (which has nothing to do with your well pump, but I've seen plenty of generator installations that are an electrocution waiting to happen).
Some power will still flow through the motor. The path is 120V from the still hot leg, through the motor, through all of the
120V loads (in parallel) on the tripped leg, and thence to the neutral. The fraction of the 120V that appears across the motor depends on the ratio of the motor impedance to that of those paralleled loads. In any event, current through the motor cannot be higher than the sum of the currents those 120V loads would normally draw.
Kinda like when I see a car comin' at me with one very dim headlight . I know right away that it's very likely that dim bulb has lost it's connection to ground .
Not knowing what type of a well and pump you are referring to, it's a little hard to respond.
The two deep wells on my properties, 350 ft and 650 ft, both use submersible pumps towards the bottoms of each well. They run off 220 volts and have NO connection to either a ground or common component of the 220 power.
In fact, any connection to ground immediately pops the circuit breakers. That means the wire feeding the pump has shorted to the pipe. I know this from bad experiences!
So, if either side of your generator 220 opens up, the pump won't run.
If you are running a shallow well pump, then I can't answer.
Is this generator supplying loads other than the pump? Single phase loads?
Even if the pump is the only load, good luck ensuring that the downstream ganged breaker will trip first. If there are other loads (between the two breakers), a gen breaker will almost certainly trip first.
What happens next will depend on what lies downstream of the (tripped) gen breaker. Single phase loads on the tripped phase will end up in series with the pump winding. While the voltage will probably collapse so that these loads become inoperative, that leg will still be energized at some voltage. If there's a fault there (what tripped the breaker), that could lead to a hazardous situation.
Best bet is to replace the two gen breakers with a ganged unit. Don't feed a line to line load from independent single pole breakers.
You can get the "aircraft style" 2-pole handle-tie lever breakers that will work fine in that portable generator - replace the two little pop-button style breakers.
There are Line Lug - Load Lug US Style breakers available that can be panel-mounted - GE, Square-D and others. But they're huge in comparison, they won't fit.
The new Murray MP series aren't that bad, and I deal with them every day in residences and retail...
But if you're dealing with industrial shops, they really should be installing Bolt-On Panelboards and breakers, they won't have those buss problems because it's clamped on with a 10-32 screw. You can get them Square-D QOB Bolt-On panels if you insist on staying with them.
When given a choice I always stay with a 1" "Industrial Interchange" style that is interchangeable in an emergency - you can stick a Cutler/Challenger or GE in a Murray panel in a pinch, or vice versa.
Stay away from Square-D Homeline, they are NOT true I.I. style and you have to modify the Homeline buss with side-cutters to get a Murray or GE breaker in, Pool Men do that to me all the time because they have a Murray breaker with them. But snipping a chunk out of the Aluminum buss breaks the tin plating and speeds up the "Self-Destruct Tin Corrosion" feature, and I'll soon be installing a whole new panel.
You can get Square D QO now, but eventually they will be discontinued in favor of the Homeline and then the fun starts.
GE is good but I won't put them in new, they have proprietary breaker stabs on their 'skinnys' and there's a cross-bar where a regular Murray or Challenger 'thick' won't plug in. You have to go get a GE breaker - but again the Pool Men just start snipping off the side cross-bars to get a Challenger that they have with them in, see above.
And the Aluminum buss stabs in any brand panel WILL fail after 20 or
30 years if they aren't treated right - like the builders that sprayed Wallboard Texture into all the open panels in the development, and then their Electricians doing trim-out just stuffed the breakers on over the gypsum splatters. Twenty years later, the panels start burning up...
Put an Aluminum Buss panel anywhere near salt water, and that's more like 5 to 15 years.
Half of that you can blame on cheap people, even if you can order the panel with a Copper Buss option most people won't pay extra for one.
You want trouble, the older Challenger Half-size split breakers with the "hook" buss stabs - they don't have a pressure spring, so they get stretched real easy and get loose on the buss stab, then start burning up the stabs.
Same thing with Zinsco breakers, especially the skinny little stabs on the R38 and RC38 twins.
And don't get me started on FPE Stab-Lok - sending 200 Amps through an
8-32 Screw to the vertical buss, and their miniature stabs that don't stay stabbed or locked into the busses. And the 2-pole breakers that fail and get jammed internally and then will not open for anything - even a roaring fire. FPE is Bad Juju, Replace The Whole Panel at the first hint of trouble.
Murray was interchangable with a lot of other brands.
American Switch Arrow-Hart Bryant Crouse Hinds Cutler-Hammer Electri-Center Frank Adams General Electric General Switch Gould GTE Sylvania Montgomery Ward Murray Siemens Westinghouse/Bryant
Sears had a series that fit at one time, as well.
A lot of breakers and panels are shipped with little or no ontact lubricant, which causes early failures. Some 'electricians' wipe it off the buss bars, causing their own problems.
Westinghouse used to make the circuit breakers for a lot of other brands, including the lower current Sqaure D breakers. I knew a Polish EE who worked for Square D at a plant in Ohio where they made large switchgear. BTW, he told the WORST polish jokes! :)
They were made in the US. Where are the failing Murray breakers made? Mexico or China?
I'm betting a big part of this is from the VFD's - they might be "officially" drawing 18A startup and 8A run, but the chopper effect of the drives throws a ton of harmonics that your regular clamp-amp can't see on the power lines and the neutral buss.
The other half of the problem is the tin-plated aluminum busses in the Murray panel - "When they are good they are very very good, but when they are bad they are rotten."
Once the tin coating is compromised the aluminum underneath starts corroding, and it'll run the whole length but you can't see it easily under the tin. Till it gets peeled off, then.... Eew.
I have a Two Strikes policy - When you go there the first time and have to shut off power, pull all the breakers, inspect and clean all the stabs with Noalox and abandon one or two as hopelessly burnt, you warn them that next time the panel has to get changed.
If it happens again, you have to stand firm or soon it will get so bad they'll have you back weekly, and worse they'll claim you are incompetent - pull the panel and put in a fresh one.
Even if the customer claims poverty and insist you "patch it again" - don't offer the choice if it's really bad. Their just being a cheap ass, some Millionaires do that as a reflex thinking they're saving money when they really aren't. And I don't want to keep dicking with the same damn problem a dozen times.
Effects of high Q-factor harmonics are very visible if you do a thermal scan of the panels at any large office building - computer power supplies are switching style also, and the Q Factor (Inductive reactance) from all those harmonics means they have to put in special panels with a way oversized Neutral Bar and conductor back to the transformer.
And the step-down 480-120 transformers for computer-heavy office buildings have to be specially built ("Q-13" or higher markings) to damp the harmonics too, or they start glowing at the Neutral connections.
This shop might need the same rework to address that many VFD's concentrated on one panel. That, and check into adding power factor capacitors and filter inductors in front of each machine to try and stop the crap at the source.
Last time I dealt with this was a bank that burned up the neutral buss in a 125A sub-panel - I put in a new 200A neutral buss to get them running again, and warned them they need to buy a better class of computers and/or get an Electrical Engineer involved.
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