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| [GMCnet] 12 volt questions [message #306578] |
Mon, 05 September 2016 21:34  |
Burt and Faye curtis
Messages: 256
Registered: June 2012
Karma: 4
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When Bert relocated the water tank to outside under the coach (no, did not
use the existing one, made a stainless tank to fit the location), he also
relocated the water pump to under drawers in the kitchen. Due to this, he
then ran a new hot wire to a switch that he installed in the electrical
compartment inside the coach. While this works, it is mighty inconvenient
to use and since I have the oven out along with the ceiling, I thought it
would be a good time to run the wire over head and connect to the existing
on from the switch at the doorway.
However, that wire appears to run up towards the ceiling and then towards
the back of the coach before returning back down behind the bath unit. If I
could find that wire at the top of it's run, it would be easy to connect
onto it there. Short of pulling the refrigerator out, that doesn't appear
to be possible, unless someone else has a solution. So, I figured that I
would just run a wire up over the ceiling and back down to the existing
wire and splice it in. While looking at the 12 v wiring diagram for 1975
-1976 coaches and following the wire from the pump to the switch, it shows
a 10 g wire going through an inline fuse at pump to a square box with a 2
in it and then becoming a 12 g wire, which then goes through another square
boa with a 2 and then on to the switch.
Hence the questions: are these boxes connection points and would I be
correct in downsizing the wire from 14g to 12g? And, is an inline fuse
needed at the pump (don't have one now) and if so, what amp?
Again, thanks in advance for the help
fay Curtis
"76 Glenbrook
Kneeland, CA
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| Re: [GMCnet] 12 volt questions [message #306583 is a reply to message #306578] |
Mon, 05 September 2016 23:20  |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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Hi Faye,
I just replaced my water pump with a constant pressure unit on my Glenbrook (modified by Clasco) In my case, the pumpn switch was above the refrigerator in a panel along with tank status display and generator controls. Clasco installed a new electrical panel with circuit breakers replacing the original GMC unit. I had a spare 20A breaker in that panel and used it to connect to the new pump. It continually tripped, so I increased the wire size to #10 and installed a 30A breaker. My new pump is certainly different from yours, but considering my experience, I would not decrease the wire size and would use #12 wire and fuse it at 20A.
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: [GMCnet] 12 volt questions [message #306584 is a reply to message #306583] |
Mon, 05 September 2016 23:28 |
Burt and Faye curtis
Messages: 256
Registered: June 2012
Karma: 4
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Senior Member |
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So Jack,
the switch is fused at 15 A and the wire to it is 12G, somewhere it becomes
10G before the inline fuse before the pump in its original run according to
the diagram. If I am understanding you, you feel I should install a 20A
inline fuse between the pump and switch and down size to 12G after this
fuse in my case. Right?
Fay
On Mon, Sep 5, 2016 at 9:20 PM, Jack Christensen wrote:
> Hi Faye,
> I just replaced my water pump with a constant pressure unit on my
> Glenbrook (modified by Clasco) In my case, the pumpn switch was above the
> refrigerator in a panel along with tank status display and generator
> controls. Clasco installed a new electrical panel with circuit breakers
> replacing the original GMC unit. I had a spare 20A breaker in that panel
> and used it to connect to the new pump. It continually tripped, so I
> increased the wire size to #10 and installed a 30A breaker. My new pump
> is certainly different from yours, but considering my experience, I would
> not
> decrease the wire size and would use #12 wire and fuse it at 20A.
> --
> Jack Christensen - K6ROW,
> '76 Glenbrook/Clasco - "The Silver Bullet",
> Sebastopol, CA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] 12 volt questions [message #306585 is a reply to message #306578] |
Mon, 05 September 2016 23:32 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Fay if the current wire to the water pump is the proper gauge and is a short run what I would do is add a 12 volt spst n.o. Relay at the pump then you can run a # 16 or 18 gauge wire to a remote switch at a location of your choosing to energize it this way you won't have to worry about large gauge wires and voltage drops.
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Mon, 05 September 2016 23:35] Report message to a moderator |
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| Re: [GMCnet] 12 volt questions [message #306587 is a reply to message #306584] |
Tue, 06 September 2016 00:15 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Faye, I am not totally understanding what you are wiring there but...
Two fuses in series will buy you nothing. So if the switch is already fused at 15 and you add a second one at the pump at 20, in the case of a short or overload the 15 is going to blow first. The second 20 probably will still be there good. So eliminate the 20 at the pump. It buys you nothing except another connection point to possibly go bad in the future.
The other thing is you keep saying "downsizing" to a 12 ga. wire. 12 ga. is a lower number than 14 ga, but the wire diameter will be heavier than 14. It was the word "downsize" that bothered me. Using heavier wire than spec will not hurt anything.
I looked at the wiring diagram for a 75 coach and everything in the circuit back to the fuse is #12 except for that one wire at the pump that says #10 I believe that is probably a error in the diagram. There would be no need for a #10 in just that piece. That is a small part of the circuit.
I haven't looked up the current requirement for a 12 volt fresh water pump but I would assume it is under 15 amps, so #12 should be good everywhere in that circuit. I would use #12 for what you are doing.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] 12 volt questions [message #306626 is a reply to message #306578] |
Tue, 06 September 2016 19:50 |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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Hi Faye,
I thought I sent a note earlier, but it's not come up so I'll try again.
I like Roy's suggestion of a relay. It's what I did to minimize voltage drop and it may be the easiest solution to your problem. I've emailed you a couple of schematics on how it might be implemented.
Like Ken, I really don't understand how your unit is wired, but like Roy, I agree #12 wire and a 15 amp fuse is adequate.
Are you going to the Coos Bay rally? If you can wait, I could stop by on my way to Coos Bay and help you resolve this problem.
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: [GMCnet] 12 volt questions [message #306627 is a reply to message #306626] |
Tue, 06 September 2016 20:40 |
Burt and Faye curtis
Messages: 256
Registered: June 2012
Karma: 4
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Senior Member |
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Jack and Ken,
Think what I am understanding is to disconnect the wire from the switch
that Bert added (switch is wired between fuse box and pump) and connect it
to the wire coming from the original switch by the entry door. Will not add
inline fuse by pump and will use 12G wire to do this. I don't see a need to
have two switches, leaving it on overnight isn't a problem with a tight
water system.
Will worry about shortening the wire run when/if i ever need to replace the
frig and can access the wires more easily.
Does this seem reasonable?
Jack, I will be going to Coos Bay, but want to get stove and ceiling in
before then. However I could run the wire over the ceiling and not connect
it and remove stove again, not that hard to do, if you think using a relay,
etc is really needed.
Please feel free to stop by regardless and or come caravan up 101 to WS
with us.We are planning on leaving the Saturday before and spending that
night at HumBug State Park, before arriving a day early for the rally.
Fay
On Tue, Sep 6, 2016 at 5:50 PM, Jack Christensen wrote:
> Hi Faye,
> I thought I sent a note earlier, but it's not come up so I'll try again.
>
> I like Roy's suggestion of a relay. It's what I did to minimize voltage
> drop and it may be the easiest solution to your problem. I've emailed you a
> couple of schematics on how it might be implemented.
>
> Like Ken, I really don't understand how your unit is wired, but like Roy,
> I agree #12 wire and a 15 amp fuse is adequate.
>
> Are you going to the Coos Bay rally? If you can wait, I could stop by on
> my way to Coos Bay and help you resolve this problem.
>
> --
> Jack Christensen - K6ROW,
> '76 Glenbrook/Clasco - "The Silver Bullet",
> Sebastopol, CA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] 12 volt questions [message #306642 is a reply to message #306626] |
Wed, 07 September 2016 01:05 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Faye,
I just remembered that I have a used Wisper King water pump in the basement. I just checked the label and it says to use a 10 amp Slo-Blow fuse. From that I can assume that the running current draw is 7.5 amps or less and it has a start up current of slightly over 10 amps for a second or two.
Based on that I can tell you that 12 Ga. wire is fine and a 15 amp normal fuse or a 10 amp slow-blow fuse should work just fine. I personally see no need for the relay, but if you choose to use one, it will not hurt anything other than adding some additional connection points in the circuit.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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