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justplumducky 11-01-2012 10:49 PM

All voltage measurements good until load is put on the circuit
It's an electric kitchen range circuit in a mobile home. 240 volts, new 50A breaker at sub-panel for this dedicated circuit..

Kitchen range (stove) is new. Back of stove was removed to make sure there was no obvious problems. Incoming wires from cord to terminal strip (3-wire cord) were checked for continuity across terminal strip to the ring lugs of the wires leading upward to the stove's control panel (switches, etc.).

The 50A receptacle in the kitchen is new and wired correctly, making sure the hold-down clamps of the receptacle are contacting bare wire and not insulation.

The cable from the receptacle to the circuit breaker box has been checked by temporarily relocating it to a vacant unit (mobile home/trailer), hooking it up to the breaker panel in that home and running the cable (with new receptacle on it) down the hall to the stove - plugged it in - powered up that stove perfectly.

Reinstalled the cable and new receptacle in the first home, plugged in the new stove again. This circuit is run off a one-switch sub-panel with a 50A breaker, which is also new (the breaker, not the box). Box is not old though - looks good if that means anything.

The two hot legs measure 240v and each hot leg to ground (or neutral) separately measures 120v. These measurements are the same at the stove terminal strip, 3-wire cord was checked for continuity (was zero ohms on both hot legs and neutral) from plug prongs to terminal strip connections.
Same measurements at the subpanel (both line side and load side) and the main panel also. All these measurements are taken with the new stove plugged into the new receptacle.

Everything is perfect until you turn a burner switch on at the stove. Then the 240 volts disappears at the main panel and the subpanel. It initially drops down to 12v momentarily, then nothing.

There is only one connection (on the park's lot for this trailer) between the meter and their circuit breaker box inside the home. This connection(s) is under the trailer, but not in a junction box of any kind - just wire splices weatherproofed with "duct seal" and electrical tape.

I can't remember if I ever checked the voltages at the power company's meter box (100A circuit breaker box immediately below the meter) while the burner switch was on. Checked this breaker box plenty of times without the stove being connected, but don't remember if I did it with the stove's burner switch on.

Does this sound like a bad connection in the cable between the trailer's breaker box and the power company's meter box?

frenchelectrican 11-01-2012 11:39 PM

First of all if you did loose one of the legs you will noticed the light will go bright or dim depending on how it connection is.

Second thing with the mobile home you should have 4 wire cord not the 3 wire cord that is not a legit set up for many years so therefore you should have black, red , white et bare or green conductor that is legit.

Ditto with the subpanels all it have to be 4 conductors as I posted above there will be no 3 conductor set up at all.

You may have bad connection at the meter pedstail this area genrally not a DIY area at all so you may have to cut the loss and get the electrician to come in and deal with it some case the splice may pulled out of the connection inside the pedestal ( I have see it happened before ) so first thing you can try is call the POCO to check their side first then talk to the park manger or landlord of that place to see what they will do next after the meter socket to below of the mobile home unit.


AllanJ 11-02-2012 08:21 AM

Are you able to see the ends of the fat wires entering the main panel and fastened to lugs? Ideally you want to be able to poke the ends of the wires with the meter probes, just to rule out a loose or corroded lug at that very spot. But someone with lots of experience should do this. A slip of the probe could cause a giant short circuit with a frighteningly large spark.

Alternatively you may choose to assume that (jump to the conclusion that) the problem is further upstream, outside, now that you measured loss of the 240 volts in your panel.

Better to have someone else turn the stove burner on while you are making measurements so the burner is not in the on position for more than a few seconds.

A loose connection will heat up and can cause a fire or at least melt the insulation on the wires.

justplumducky 11-02-2012 08:30 AM

Thx French~ - I understand about the symptoms of one leg being out - also about the code requiring a separate ground wire, but in this instance, at this point anyway, I'm interested only in identifying the problem that's killing the voltage with a load on the circuit (one burner burner switch being turned on). Voltages are good at all points, including at the meter and from the meter, to the terminal strip at the lower back end of the stove. All is good until you turn the burner switch on - then the voltage goes bye-bye!

Duke Energy has been out twice already, even came into the house to help me check out the main panel. He also used a temporary load-imbalancer jumper on the meter, then came into the house to check measurements (the neutral in particular) with some appliances in the trailer running.

Park is not interested in helping until they're convinced that the problem is not in the house. Park management here is less than professional (an understatement). I am helping the resident here with this problem. They do not have the money, at this point, to bring in a qualified pro to locate the problem.

So, what I'm going to do, unless you have a better suggestion (very grateful for your input so far and will welcome more of the same), I'm going to disconnect the stove cable at the breaker box and hook it up directly to the cable under the home where there are splices from the cable from the meter to the house. There is no junction box - only connectors. If I hook the stove up there, it would tell me if the problem is in the park's cable up to that point, or if it's in the cable (to the house) after that point. Park owner is not sure yet (played dumb when I asked) if the entire cable all the way to the breaker box is his problem or not, so we'll see. In other words, he may not take responsibililty for the cable after the splices. However, if I hook up at that point and the stove is still not working, I am quite sure he'll have to fix the problem then. If it's after the splices, we'll have no problem (objection) replacing that cable. Any reason this shouldn't work? Toward identifying the problem I mean, as to which side of the splices the fault is on...

I bought a small Master lock to secure the circuit breaker box at the meter while I'm hooking up to the cable under the trailer, at the splices point. I'll also put a sign on the box ("work in progress on this cable")

justplumducky 11-02-2012 08:36 AM

Yes, all connections have been checked and tightened at the panel and the under-trailer splices also. Your point about the burner switch on for only a few seconds is well taken - thx.

I was replying to French~ when your message came in. Please check out that reply and tell me if you agree with my plan to connect the stove cable at the point of the underground splices.

Thx much for you help.

frenchelectrican 11-03-2012 12:09 AM

Did the mobile home have electrique water heater in there ? if so or the electrique dryer one of the two if you turn them on did the lights went dim or brighter ??

And this is the only circuit that affect if so then you will have to crawl underneth the mobile home and check the cable to see if any damage there and I am not too surpised to see something is damaged there.

Note : it pretty common to see the NM cable get rottenout underneath the mobile home unit and by the code it have to be UF cable otherwise run it in the conduit.


justplumducky 11-03-2012 05:54 AM

French~, there is no dryer, but there is an electric water heater (dual 3200w, 240v). No other 240v appliance. No dimming of, or erratic operation of lights or anything else. I will check the water heater today, and be looking for cable damage under the home.

Thx for you help.

AllanJ 11-03-2012 07:27 AM

Do you lose the 240 volts at the meter? That would mean the problem is at the meter or further upstream.

Also flip off the breaker for the hot water tank. Do any of the measurements change or does anything behave differently?

You the owner are responsible for infrastructure. The fact the resident doesn' have the money for an electrician is irrelevant.

Marc05 11-03-2012 08:39 AM

On most panels the phases are staggared going down the left and right side of the panel, a,b,a,b,a,b etc.. sometimes a panel, not sure which brands, have them staggared, a,a,b,b,a,a,b,b,a,a etc.. meaning it is easy to put a 2 pole breaker on the same phase.

Your measurements dont really suggest this could be the case, but it is just a quick check to make sure they are on different phases.
just a thought

justplumducky 11-03-2012 10:15 AM

Allan - I will check for 240v at the meter today (going there at Noon) with the burner switch turned on. Previously, there was always 240v at the meter with the stove plugged in, but not turned on.

Will also turned the water heater breaker off and see what happens.

I am not the owner, but the park I live in (different one) requires residents to be responsible for the cable after the junction box (from the j-box to the home's service panel). The j-boxes are on the homes' lots, right next to the homes.

Is this different from other parks? Is it dependent on state law (Ohio in this case)?. Maybe I should check. Maybe the owner is free to dictate such policy for anything above ground level? That's their policy on the service line (water)... that the water line after it exits the top of the crock (the pit where the water service line comes out of the ground), it's resident responsibility (leaks, freeze damage, etc.).

Marc~, I do understand about the staggered 120v legs, but this stove is connected to a 50A circuit breaker in a subpanel right above the main panel, and the jumper wires (or whatever their called) are taken directly off the lugs at the main panel where the two hot legs come in to the panel. But thx for the thought, because now I'm wondering if there's isn't something wrong with the water heater, that's draining the voltage? This possible? It's a 240v, dual 3200w element w-heater. It's on a circuit breaker of the main panel.

I'd like to tell you more about what I'm talking about the water heater), but I have to leave now- supposed to be there at noon. Will post back again this evening.

AllanJ 11-03-2012 11:43 AM

If you get 240 volts across the breaker terminals or across the stove hot conductors at any time then the breaker set is correctly positioned in the panel.

jrclen 11-03-2012 05:23 PM


Originally Posted by justplumducky (Post 1042898)
Does this sound like a bad connection in the cable between the trailer's breaker box and the power company's meter box?

Yes it does. Check the connections under the trailer. Also measure the voltage at the meter pedestal if you can. With the stove on and with it off. What you are describing is a classic symptom of a bad connection or a bad conductor. You just need to find where it is.

justplumducky 11-03-2012 08:37 PM

Thank for jumpin' in here jrclen... (voltage at the meter with the stove on and off is 240v and 120v each hot leg to ground).

In my last reply, before I had to rush off, I was going to explain that their water heater is not wired properly - they have one leg of the 2-wire cable (plus bare wire ground) connected to only one 120v circuit breaker and the other leg connected to the neutral bus bar. Evidently, that gives it 120v, which according to the homeowner is making their water heater work ok (must take it a long time to heat up). I'll worry about correcting that situation later.

Today, I isolated the water heater entirely (removed the hot and neutral from the main panel), and it didn't make any difference - still the same problem with the stove. However, now I have a bit of story to tell about what I did today (stove still not working). You'll see why I'm telling the whole story when I get to the end of it. Discovered something unusual (for my limited experience anyway).

Okay... I previously mentioned that there are three splices in the cable running from the power company meter (circuit breaker box immediately below the meter) to the service panel at the back of this home. The cable is underground of course up to the home - surfaces at the front corner of the home (under the trailer), then runs over ground all the way back to the point where it goes up thru the floor and into the panel. Half way back under the home is where these 3 splices are (two hot legs and neutral) - no junction box anywhere under this home, or around it.

I cut out the old splices and installed new connectors- didn't bother to see if the old ones were bad, because they had Duct Seal on them (wasn't very pliable) - stove still no 240v when turned on.

Next thing I did was to disconnect the two hots and neutral from these new connectors (the two hots and neutral running from these splices/connectors, over ground and back to the service panel), then I disconnected the stove cable from the subpanel (next to the main breaker box) and connected it directly to the new connectors. Now the stove is connected directly to the breaker below the meter (wanted to see which side of the splices the problem was on). Stove still not working - same symptoms, so it seemed obvious, now, that the problem is in the park's cable from the meter up to those splices.

What I discovered (I said above was unusual for my limited experience) was that when I disconnected the stove cable from those 3 splice connectors and re-connected the cable that goes back to the panel, I flipped the 100A breaker at the meter back on, went into the home, turned all the individual breakers back on (no main breaker in this panel) and no lights (at least in the two bedrooms nearest the panel) would come on. Went back outside and reversed the two hot legs in the connectors. Didn't touch the neutral.
Went back in the home - lights now working again. This I don't understand.

The only reason I thought to go out and reverse the two hot legs was because someone told me to give that a shot (previously) to see if that would fix the stove problem. But I never did try it.

Is it possible that after I get this stove cable hooked back up to the panel on Monday, that if it still isn't working, reversing the two hot legs on the load side of the breaker (at subpanel) might make a difference?

joed 11-03-2012 10:00 PM

One of the hot leads is bad. Half of the breakers in the panel won't be working. The bedrooms light were on the bad leg on the first try. When you swapped the black wires you put the bedroom onto the good hot wire and something else not does not work.

The water heater could be a 120 volts or they did the neutral connection because of the bad hot lead. At least they would get hot water but it would take a long time to recover. If they never drained the tank down then they may not have even noticed.

AllanJ 11-03-2012 10:07 PM

Verify that the water heater needs 240 volts before hooking it up to 240 volts.

Is part of the run from the meter (voltage okay) to the main panel (voltage problems) underground? It is not unusual for aluminum underground feeds to rust out because the insulation got chewed by animals. Then you can measure the full 120 or 240 volts with no load and there is significant voltage drop under load. Here you may have lost one of the two hot leads.

You can test for a broken conductor (for DIYers, downstream of a main breaker only) by running an across the floor or across the lawn jumper for a few minutes. But be careful, you don't want to jumper the A hot leg at the meter to the B hot leg at the panel. Verify using your voltmeter before connecting the second end of the jumper

Then turn on the stove burner.

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