Air Conditioner Hazard Potential - Page 3 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 


Like Tree3Likes
Reply
 
LinkBack Thread Tools
  #21  
Old 11-25-2013
ebs001's Avatar
Senior Member
 
Join Date: May 2006
Location: Ottawa, Canada
Posts: 2,108
Thanks: 5
Thanked 21 Times in 19 Posts
Rep Power: 9
ebs001 is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by svHyLyte View Post
Subsequent to my last post, I have spoken with the engineers at the AC Maker. The red wire I observed is near to, but has nothing to do with the fan assembly. The white and black cables are 120v and power the fan. The copper tube that temporarily connected these wires merely completed the circuit in place of the connection normally made by the fan speed control module on the circuit board which was inactive in the event. The insulation on the green "neutral ground" cable was damaged but not fully compromised and so not involved in the event.

FWIW...
Now you do have a potential hazard. If the wires in question are indeed 120 volts the whole A/C unit becomes "live when those wires touch the copper tubing. Touch that baby and a good grounding source and your bye bye. Once a 120 volt live wire touches ground it should cause the over current device to trip. That is the built in safety by grounding the system so you don't die.

I really doubt this is the case. The fan speed control will be is 24 volts.

Last edited by ebs001; 11-25-2013 at 05:41 PM.
Reply With Quote Share with Facebook
  #22  
Old 11-25-2013
ebs001's Avatar
Senior Member
 
Join Date: May 2006
Location: Ottawa, Canada
Posts: 2,108
Thanks: 5
Thanked 21 Times in 19 Posts
Rep Power: 9
ebs001 is on a distinguished road
Re: Air Conditioner Hazard Potential

I looked here diagram marine air conditioning system which seems like a typical schematic for an A/C unit.

The fan is 120 volts but all 120 volt wire is protected by a circuit breaker. Any live wire touching ground will cause the circuit breaker to trip.

The 24 volt wires are neither protected by a circuit breaker nor is one side grounded.

The only way the fan can come on in the scenario you described i.e. frayed wires completing the circuit, is by energizing the fan coil which is done on the 24 volt side.

In the schematic above there is a fan cycle switch which can turn on the fan and it could be wonkie and the frayed wires were a coincidence. If this is the case moving the wires will be of no consequence.
Reply With Quote Share with Facebook
  #23  
Old 11-25-2013
deniseO30's Avatar
Move over Joan Rivers!
 
Join Date: Nov 2006
Location: Bristol pa
Posts: 5,872
Thanks: 51
Thanked 72 Times in 64 Posts
Rep Power: 9
deniseO30 will become famous soon enough deniseO30 will become famous soon enough
Re: Air Conditioner Hazard Potential

Pops in again... wonders if she should drop off a pee pot for the wizzing contest w or stay with a cam to take photos of the chest thumping when it begins..
__________________
Denise, Bristol PA, Oday 30. On Tidal Delaware River, Anchor Yacht Club. New Website!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

my current "project"!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #24  
Old 11-25-2013
therapy23's Avatar
Back to just the Jon boat
 
Join Date: Jul 2007
Posts: 911
Thanks: 1
Thanked 5 Times in 5 Posts
Rep Power: 8
therapy23 is on a distinguished road
Re: Air Conditioner Hazard Potential

I don't want the name of the mfgr to avoid it.

I would want it to decide to buy it.

That was great service!!
Reply With Quote Share with Facebook
  #25  
Old 11-26-2013
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,384
Thanks: 0
Thanked 23 Times in 22 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by deniseO30 View Post
Pops in again... wonders if she should drop off a pee pot for the wizzing contest w or stay with a cam to take photos of the chest thumping when it begins..
I'm wondering if Denise has anything constructive to add to the discussion, or whether she is just popping in to make her usual sexist remarks!
__________________
1979 Santana 30 Tall Rig
Hull#101
Reply With Quote Share with Facebook
  #26  
Old 11-26-2013
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,384
Thanks: 0
Thanked 23 Times in 22 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by ebs001 View Post

BTW here is the definition of a short circuit from the on line free dictionary

(Electronics) a faulty or accidental connection between two points of different potential in an electric circuit, bypassing the load and establishing a path of low resistance through which an excessive current can flow. It can cause damage to the components if the circuit is not protected by a fuse.

I was unable to find anywhere that said a short circuit was just an alternate path. Maybe HVAC guys have their own definition that is different than the rest of the world.
I guess you missed this definition from the very same page that you cherry-picked your definition from:
short circuit
n.
A low-resistance connection established by accident or intention between two points in an electric circuit. The current tends to flow through the area of low resistance, bypassing the rest of the circuit.


I'm not really interested in the semantics. In my world there are many different kinds of short circuits that can happen, even a short that bypasses a switch instead of a load!

Quote:
X1 or X2 of the 24 volt transformer has to be grounded in order for the hot to cause a short to ground. You are without question wrong in that regard.
Well I have to say it is rare to encounter a control transformer that is NOT grounded so today I thought I would test my assumption by disconnecting the ground on a transformer. What do you know! Even with the ground disconnected we still have 27v potential to ground!


Funny though on another, larger transformer I had an interesting result. I disconnected both X terminals and the ground, and checked the voltage potential to ground. Damn! 173 volts! (that is supposed to be a 24v secondary btw) Do ya think that is why the secondary is supposed to be grounded?


For the record though, you are correct that if there is no ground reference on a transformer shorting one x terminal to ground will not blow a breaker, it will merely give it that ground reference. The thing is, almost ALL control transformers ARE grounded. I worked on 7 different units today alone, and every single one of them was grounded.

Right Denise?
__________________
1979 Santana 30 Tall Rig
Hull#101
Reply With Quote Share with Facebook
  #27  
Old 11-26-2013
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,384
Thanks: 0
Thanked 23 Times in 22 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by ebs001 View Post
Now you do have a potential hazard. If the wires in question are indeed 120 volts the whole A/C unit becomes "live when those wires touch the copper tubing. Touch that baby and a good grounding source and your bye bye. Once a 120 volt live wire touches ground it should cause the over current device to trip. That is the built in safety by grounding the system so you don't die.

I really doubt this is the case. The fan speed control will be is 24 volts.
Yes, this is what I have been trying to say! So assuming that it was indeed the 115v circuit that was shorted. (yes I said SHORTED!) Perhaps what happened was that the insulation on the individual conductors melted, and those wires contacted each other while remaining electrically isolated from the copper discharge line by the molten remains of the outer cable casing. That would explain why the breaker didn't trip.

Either that or the unit isn't grounded properly.

24v speed controller?
__________________
1979 Santana 30 Tall Rig
Hull#101
Reply With Quote Share with Facebook
  #28  
Old 11-26-2013
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,384
Thanks: 0
Thanked 23 Times in 22 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by therapy23 View Post
I don't want the name of the mfgr to avoid it.

I would want it to decide to buy it.

That was great service!!
I agree, the manufacturer should be recognized for making good on something they could have easily wriggled out of. The technician that installed the unit is the one that is supposed to catch problems like that. Cable ties don't just break by themselves. He probably broke the cable loose when installing the unit, and then failed to secure it again when it was in.
__________________
1979 Santana 30 Tall Rig
Hull#101
Reply With Quote Share with Facebook
  #29  
Old 11-26-2013
ebs001's Avatar
Senior Member
 
Join Date: May 2006
Location: Ottawa, Canada
Posts: 2,108
Thanks: 5
Thanked 21 Times in 19 Posts
Rep Power: 9
ebs001 is on a distinguished road
Re: Air Conditioner Hazard Potential

SchockT, you cannot disconnect the ground from X1 then measure X1 to ground and get potential. You are actually talking about the bonding connection and 120/24 volt transformers are bonded. If X1 is grounded and you disconnect the bonding wire then you will of course get potential between X2 and ground, between X1 and X2 but zero between X1 and ground.

If on the other hand neither X1 nor X2 is grounded you have an isolating transformer with neither line having potential to ground. This is exactly what the old razor plugs were back in the day before GFCIs were introduced for bathrooms.
Reply With Quote Share with Facebook
  #30  
Old 11-26-2013
svHyLyte's Avatar
Old as Dirt!
 
Join Date: Nov 2008
Location: Tampa Bay Area
Posts: 2,573
Thanks: 11
Thanked 87 Times in 83 Posts
Rep Power: 6
svHyLyte is on a distinguished road
Re: Air Conditioner Hazard Potential

Whoa... I did not intend to give rise to such a controversy. I just thought posting a notice would be wise in case others might have the potential for the same kind of problem.

Our unit came "pre-packaged/wired" and is/was meant to be simple enough for owner installation. One merely positions the machine, bolts the base down, plugs a power cable into a suitable 120 source, plugs the power cable for the raw water pump into a plug provided for it in the machine's wiring bundle, connects the raw water in-put and discharge lines and positions the thermostat/control panel in a convenient location for managing the operation of the device. All of the wiring goes to a 10" square, 4" deep box which holds the device's circuit board/brains and is mounted in a convenient location adjacent to the machine. The owner/installer's "wiring" efforts involve nothing more than connecting two plugs.

The wire ties on the machine itself are (or are supposed to be) thin metal straps with a foam rubber liner (that bears against the enclosed wiring) fastened to the base in the proper position with small sheet metal screws. In our case, one of these strap ties was omitted and a simple plastic zip tie (that broke) was used instead. With the strap ties, the wiring is/would have been firmly affixed and not subject to chafe as the yacht moves. Further, the hot gas line from the compressor to the heat exchanger (where it is cooled by the raw water) is supposed to be enclosed within a small foam insulation tube, which was missing. The combination of missing insulation and incorrect wire tie is evidently what gave rise to our problem approximately 19 months after the machine was installed.

For what it's worth, the technician that tracked down the problem/error on our boat was fit to be tied when he did so. He evidently went back to the company and (according to the company's owner) got into a heated shouting match with the people in the assembly department over the error.

N'any case, the problem is solved and I have looked at two other boats in our marina with similar AC systems by different manufacturers, one by Flagship and one by Mermaid. The wiring in both was done in a manner similar to mine, with plastic zip ties at some points and insulated strap ties at others. We added reinforcements where it looked to be advisable on those systems but neither had any problems so my situation may have been relatively unique.

FWIW...
__________________
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Air conditioner questions saillife Gear & Maintenance 6 08-13-2010 02:49 PM
Paint in the Air Conditioner labestia Gear & Maintenance 3 06-29-2009 09:16 AM
Recommissioning Air Conditioner mgmhead Gear & Maintenance 8 06-09-2009 11:45 PM
Smoke from air conditioner dohenyboy Gear & Maintenance 7 07-28-2007 11:11 PM
Air Conditioner randall2v Gear & Maintenance 0 06-30-2004 01:39 PM


All times are GMT -4. The time now is 05:37 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.