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| Electricity 101 [message #169377] |
Sat, 12 May 2012 19:37  |
SThornbg
Messages: 127
Registered: September 2011
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First, I plead guilty to being easily confused by anything more than a simple two wire circuit. Third and fourth wires become totally cosmic.
Trying to verify 120 VAC at my water heater - measuring across the major black wire (jumpers to the thermostat) and the major white wire (tied to one side of the heating element). No voltage.
The switch toggle seemed flimsy but the outlet worked fine. I elected to replace the switch.
The old switch has three connect points - two black wires across the switch and one common white (plus the bare wire ground).
The new switch/outlet has one copper contact on each side - one adjacent to the switch and the other adjacent to the outlet. There are two black contacts side by side with no bonding tab. So, I think two independent circuits - white one side, black the other side.
I have two black wires and two white wires coming into the work box. One black/white pair powers the outlet. The remaining white wire shows continuity with the white wire at the heating element. The remaining black wire does not show continuity.
With the last two wires connected across the switch with the circuit breaker turned on and the switch turned on, there is no power at the water heater.
I am looking for help understanding where all my little electrons are coming from and where they are supposed to be going to put power at both sides of the water heater.
Thanks for any and all guidance.
Steve Thornburg
South Bend, IN
77 PB 455 "Tinker Toy"
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
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| Re: Electricity 101 [message #169390 is a reply to message #169377] |
Sat, 12 May 2012 22:28  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| SThornbg wrote on Sat, 12 May 2012 20:37 |
First, I plead guilty to being easily confused by anything more than a simple two wire circuit. Third and fourth wires become totally cosmic.
Trying to verify 120 VAC at my water heater - measuring across the major black wire (jumpers to the thermostat) and the major white wire (tied to one side of the heating element). No voltage.
The switch toggle seemed flimsy but the outlet worked fine. I elected to replace the switch.
The old switch has three connect points - two black wires across the switch and one common white (plus the bare wire ground).
The new switch/outlet has one copper contact on each side - one adjacent to the switch and the other adjacent to the outlet. There are two black contacts side by side with no bonding tab. So, I think two independent circuits - white one side, black the other side.
I have two black wires and two white wires coming into the work box. One black/white pair powers the outlet. The remaining white wire shows continuity with the white wire at the heating element. The remaining black wire does not show continuity.
With the last two wires connected across the switch with the circuit breaker turned on and the switch turned on, there is no power at the water heater.
I am looking for help understanding where all my little electrons are coming from and where they are supposed to be going to put power at both sides of the water heater.
Thanks for any and all guidance.
Steve Thornburg
South Bend, IN
77 PB 455 "Tinker Toy"
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Steve,
There is undoubtedly an Open (not a short) someplace. The trick will be to locate it.
You can get a wiring diagram of the Bdub site. Print it - in pieces if you have to but get a copy that you can work with and read. Trace the power to the water heater with a highlighter.
You seem to have a meter.
With the breaker box open, and the meter set for AC volts, put one probe on the neutral bar (where all the white wires go) and read the terminal on the breaker. Should be 120.
While you are at that breaker, look for the wire nut that connects that breaker to two other black wires (3 in that wire nut). Pull on it. You can put a probe inside it if you care to, but the pull test works best.
With the circuit still live, test for power between the white and both blacks on the switch? If both are not hot, at least one should be. Close the switch now both should be....
We are going to skip a box and come back to it if we have to.
In the water heater, there is the heating element and a control switch (thermostat). The control switch should have a black jumper that goes to the heater. With things live, check for power between the black coming into the control and the white on the heater. Power there? Good, now check again for power across the heater.
No? The controller is open. Some coaches controllers have a separate over temp safety (a small item that often has a reset button). This may or may not be a separate component.
If there was power at the switch, but none at the water heater, follow the cable back to the other box that is supposed to be near the water heater. Open it up and check those wire nuts and then check the black wire there for power.
According to the diagram there are a number of wire nuts in the system. I have had three of these come loose in my coach. If the coach is still as built, you should check every one of these that you come across.
If you haven't found the problem now, we need to know what you have found so we can make a guess where else to check. This should have covered everything.
I won't be back at the keyboard until late tomorrow.
Good Luck,
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Electricity 101 [message #169391 is a reply to message #169377] |
Sat, 12 May 2012 22:41 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
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Senior Member |
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Steve,
Perhaps I can give you a little help.
First, be sure there is water in the heater before you even try to turn it on. If it is empty you will burn out the element.
AC wiring ALWAYS uses a black wire as "hot", a white one as neutral and either bare or green as ground. There should never be any voltage between white and ground, they are essentially the same. In a "live" circuit there should be 115 volts between black and either white or ground. The black and white are the current carrying pair, the ground is for safety.
Look at the connectors on your switch/outlet. The connection screws will be either silver or brass colored. Black (hot) wires are connected to the brass colored screws, white to the silver. There should be a green screw adjacent to one of the mounting tabs, this is for the ground.
On a combination switch/outlet a white wire from the breaker box should be connected to a silver screw, this feeds the "neutral" to the outlet. (A second white wire may be connected there also carrying neutral on to another outlet and/or to the heater.) A black wire from the breaker box should be connected to a brass screw bringing 115 volts to the outlet. There is most likely a jumper from this screw to another carrying the 115 volts into the switch (your outlet/switch may have an internal connection so one brass connector feeds both the outlet and the switch. I think this is rare.) (And like the connection to the silver terminal, there may be yet another black wire sharing the brass connector that takes 115 volts on to another outlet.)
In either case another brass connector on the outlet/switch should have a black wire taking 115 volts from the switch to the thermostat on the heater.
Confused yet?
OK, now for some testing. Connect one side of your volt meter to a convenient ground. Poke the other test lead onto the screw with the black wire from the breaker, you should see 115 volts. Now poke it onto the screw that you think feeds current from the switch to the heater. You should see 115 volts with the switch on, nothing with it off. If you don't the switch is bad.
If you got the right black wire and if the switch works, move over to the THERMOSTAT on the heater (which is full of water, right?). With the switch on you should see 115 volts on the black wire coming from the switch. If you do, move the probe to the black wire connected from the thermostat to the heating element. If you see 115 volts the thermostat is probably OK. If you see nothing the thermostat is probably NG.
Finally, move your second probe from the ground to the white wire connection on the heating element, the other probe to the black connection. If you see 115 volts but no sign of water heating then the element is probably NG.
AND, there is always the possibility of a bum connection somewhere between hither and yon.
Be careful, 115 volts hurts.
Glenn (I'm not an electrician but I play one on TV)
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
[Updated on: Sun, 13 May 2012 16:14] Report message to a moderator |
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| Re: [GMCnet] Electricity 101 [message #169413 is a reply to message #169391] |
Sun, 13 May 2012 09:00 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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On Saturday, May 12, 2012, Glenn Giere wrote:
>
> AC wiring ALWAYS uses a black wire as "hot", a white one as neutral and
> either bare or green as ground. There should never be any voltage between
> white and ground, they are essentially the same. In a "live" circuit there
> should be 115 volts between black and either white or ground. The black
> and white are the current carrying pair, the ground is for safety.
>
>
Glenn, let's not be too simple. "Always" is always a dangerous word with a
GMC. Lots of time for previous owners to make undocumented changes that
violate norms.
The neutral (white wire) and the safety ground (green/bare wire) should NOT
be connected in the panel. They should only be bonded (connected) at the
source, which is either a main panel (outside the coach) or a generator.
So, if the Onan is connected or campground power is plugged in, the neutral
and ground should be the same. If not, they should be isolated. You'll
notice the neutral bus in the coach's panel is insulated from the
panel--it is considered a sub-panel.
The black wire is the source of pressure (voltage), which it both pushes
and pulls through the load (that's what makes it AC), assuming the wire
colors haven't been monkeyed with by a PO.
A switch merely creates an open or closed connection in the black wire. The
white wires should just be tied together around the switch. The load
(heating element) should have a black wire on one side and a white wire on
the other. The black wire also goes through other switches (e.g.
thermostat) as Matt described.
120VAC doesn't just hurt, it can easily kill. Thus, always test a circuit
before assuming anything. Maybe there's a GMCer with electrical experience
nearby who can help.
Rick "a little scared to give advice on testing hot AC circuits over the
net" Denney
--
'73 230 "Jaws"
Northern Virginia
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| Re: [GMCnet] Electricity 101 [message #169444 is a reply to message #169413] |
Sun, 13 May 2012 16:09 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
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Senior Member |
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Rick is right so let me clarify. In the US electrical code black is ALWAYS hot.
From your post it sounds like this is so in your coach. If black is not hot stop right here and find out why.
Glenn
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: Electricity 101 [message #169455 is a reply to message #169377] |
Sun, 13 May 2012 17:49 |
SThornbg
Messages: 127
Registered: September 2011
Karma: 0
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Senior Member |
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Thanks guys for all your help and guidance. Armed with a bit more confidence from your advice, I dug a bit deeper and found that the black wire going to the WH was pulled loose from the jumper wire to the thermostat and the separated ends were lost up into the wad of insulation above the thermostat. Also, I was trying to make two separate circuits at the switch/outlet. When I got the common white sorted out and realized there was only one black wire power source, everything came together and I now have power across the WH. I have not tried to run the WH yet as I have not filled the water system, but that will probably come tomorrow.
Just gave the element bolts a good shot of PB Blaster in case it proves that the unit does have to be replaced. At least now I know that I have power up there.
Steve Thornburg
South Bend, IN
77 PB 455 "Tinker Toy"
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
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| Re: [GMCnet] Electricity 101 [message #169524 is a reply to message #169377] |
Mon, 14 May 2012 09:29 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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It sounds from here like you're describing a bad thermostat on the water heater. And, you've shown that, so far, there's no need to unship the heating erlement. The black wire on the heater element should go to the thermostat, the other connection on the 'stat should go to the switch in the work box. Quick n dirty test - clip lead (use decent size wire) the black at the switch to the black on the water heater and seef it gets warm. If it does, locate and replace the thermostat.
--johnny
From: SThornbg <SThornbg@aol.com>
To: gmclist@temp.gmcnet.org
Sent: Saturday, May 12, 2012 8:37 PM
Subject: [GMCnet] Electricity 101
First, I plead guilty to being easily confused by anything more than a simple two wire circuit. Third and fourth wires become totally cosmic.
Trying to verify 120 VAC at my water heater - measuring across the major black wire (jumpers to the thermostat) and the major white wire (tied to one side of the heating element). No voltage.
The switch toggle seemed flimsy but the outlet worked fine. I elected to replace the switch.
The old switch has three connect points - two black wires across the switch and one common white (plus the bare wire ground).
The new switch/outlet has one copper contact on each side - one adjacent to the switch and the other adjacent to the outlet. There are two black contacts side by side with no bonding tab. So, I think two independent circuits - white one side, black the other side.
I have two black wires and two white wires coming into the work box. One black/white pair powers the outlet. The remaining white wire shows continuity with the white wire at the heating element. The remaining black wire does not show continuity.
With the last two wires connected across the switch with the circuit breaker turned on and the switch turned on, there is no power at the water heater.
I am looking for help understanding where all my little electrons are coming from and where they are supposed to be going to put power at both sides of the water heater.
Thanks for any and all guidance.
Steve Thornburg
South Bend, IN
77 PB 455 "Tinker Toy"
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Electricity 101 [message #169545 is a reply to message #169391] |
Mon, 14 May 2012 10:51 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
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Not to hack this thread on water heaters, but
a really basic 101 question.
What size are the breakers in a camp ground outlet with 50 amp service?
That can't be two 50's as I just read somewhere?
Two 25's ganged as 50 ? If you had an roof a/c on each side, is there enough left for the microwave?
Thanks
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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| Re: [GMCnet] Electricity 101 [message #169549 is a reply to message #169545] |
Mon, 14 May 2012 11:08 |
Dave Mumert
Messages: 272
Registered: February 2004
Location: Olds, AB, Canada
Karma: 0
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Hi
One would logically expect a two pole 50 amp breaker giving two 120 volt 50
amp feeds, or one 240 volt 50 amp feed.
But we are talking campgrounds here so that may not always be the case.
Two pole breakers are just two standard breakers mounted together with the
actuators connected so they both shut off (and turn on) together.
Dave
> Subject: Re: [GMCnet] Electricity 101
>
> Not to hack this thread on water heaters, but
> a really basic 101 question.
>
> What size are the breakers in a camp ground outlet with 50 amp service?
>
> That can't be two 50's as I just read somewhere?
> Two 25's ganged as 50 ? If you had an roof a/c on each side, is there
enough
> left for the microwave?
>
> Thanks
> --
> Don
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