Central A/C Wiring

I was doing some electrical work yesterday, and I accidentally nipped one lead of the 240 volt circuit (10/2 w/ground).

(Needless to say I really spooked myself!)

I turned off the breaker (double-pole 40A) to be safe.

What I would like to know is -

Given enough slack in the cable, can I connect the ends in a junction box with wire nuts, or do I have to rerun the entire line from the maintenance panel to the outside disconnect?

Secondly,
Would what happened have any affect to the outdoor condenser unit? (The unit is 30 years old.) When the breaker was on, I had the thermostat call for cooling, but only the fan came on, but not the outdoor unit. There was no power at the outdoor unit as I have a cutoff switch (installed by the power company to allow them to cut A/C during brownout conditions) and the green indicator lamp is off.

Thank you.

 

My first question is.....Why the______ are you snipping on a hot wire ????

You can splice the wire in a j-box provided that you can obtain 6 inches of excess wire from each direction to make the splices with. If this can't be achieved , you could add 2 junction boxes and run a new piece of 10-2 w/grd between them. The light company probably had the relay open at the outside unit which would not allow the unit to run. That is its purpose!

 

I would help if you would tell us where you nipped this cable. Is it in an attic, underground, ??? Also tell us how much damage you did.

 

As I stated originally, I nipped it by accident. I was working in the basement and I was just tightening the cover on a nearby j-box when the screwdriver slipped off the screw and hit the cable. As for damage, it looks like I put put a small hole on the one lead. Nothing looks fried. I think there is enough slack to make the connection in a j-box.

Generally, I excersize safety working with electricity and when I run new circuits or rework old ones, I lay them out on paper first and reference my Time-Life books for more information.

 

I know this wasn't the original question, but shouldn't that #10 cable be protected by a 30 amp fuse or breaker? Wouldn't a 40 amp breaker normally serve a #8 wire?

 

This circuit was already wired this way when I bought the house 12 years ago.

 

I do appreciate the replies to my original post, but no one has answered the second part of the post - namely, would there have been any ill effects to the outdoor condensor unit that is on this circuit? I would appreciate knowing.

Thanks.

 

Did you check for voltage at the line side of the utility company's switch or on the load side of the breaker? If you don't have 120+ volts line to ground and 240+ volts line-to-line, the breaker could be defective. If could have worked O.K. until it tripped and then malfunctioned when you tried to reset it.

 

When I nipped that one side, the breaker didn't trip. I turned it off manually. I haven't had a chance to go out and check the line side, since it never seems to stop raining here in NJ. If I get a dry moment outside I will check.

 

no damage to the outdoor unit has occurred, was it running at the time? a 30 year old a/c is pretty inefficient and unreliable.

 

The unit was not running at the time and the thermostat was set for heat. I know that the unit is old, and inefficient, but it has been reliable for my needs. I'm fortunate that I have a cousin in the HVAC biz and my wife & I have a friend in the biz as well. Unfortunately, its the replacement cost that we can't afford right now. I would love to replace the A/C and heating systems. Does anybody have a recommendation on brands?

 

on the hvac forum you will get a lot of opinions. i recommend carrier or trane, but there are good quality "value line" units. what brand is that relic of yours?

 

The relic is Singer. Ironically, the guy who installed it lives next door to me. Unfortunately, he's out of the biz, since he's now 91 years old. He worked up until he had some health problems that started about 5-6 years ago. My cousin, when he first saw the ductwork (in 1991), commented, "A real tinbender did this!". I asked him if that was bad. He said no, that it was all done by hand. I then asked him if he wanted to go next door to meet the tinbender.

I will look in the HVAC Forum for the opinions. Thank you very much.

 

I was asked to give an update to this post.

I ran a new piece of 10/2 w/ground from the breaker to a j-box and brought in the other end of the cable and connected color to color and ground to ground, even grounding the j-box as well.

When I turned the circuit back on, I set the thermostat to cool and pushed the temp. down enough to call for A/C. The blower came on, but the outdoor unit didn't start. I looked at the power company's "brownout switch" and I didn't see any lights on it.

So I turned off the A/C, went downstairs and tripped off the breaker. I then went outside to the outdoor disconnect and pulled out the "plug" in the disconnect. Renenergized the circuit and using a volt meter, I tried to determine the voltage at this point. I believe it said 50 volts - on a 240 circuit.

Any thoughts? At this point, I'm ready to call in the A?C tech to look at it.

Thank you.

 

Remove the cover off the breaker panel and check the voltage across the breaker terminals. If you don't "read" 220 volts then check for voltage across other breaker terminals to be sure you'r tester is not the problem.

You must read 220 volts across the breaker terminals before proceeding further. If the breaker tests OK then check for 220 volts across the Black & White wires in the J.B.----Good Luck!!!

 

I get 220 volts across breaker terminals and 220 volts at the supply side in the j-box.

 

you have a low voltage problem, if proper high voltage is present at the unit. does the unit "click" when the tstar is turned to cool? check the small wire going outside for breaks, you may have safeties in line as well.

 

You must read 220 volts across these connection points in this order-----the breaker terminals----the Black-to- Black and White-to-White JB conections--the Line terminals of the of the dis-connect--the Load terminals of the dis-connect--the Line terminals of the compressor contactor.-----Good Luck!!!!

 

I finally had contacted my utility company, Public Service Electric & Gas of New Jersey. I have a contract with them for the C/AC system. The tech came, and when he noticed the brownout controller on the unit, he asked if I had let the t-stat call for cooling for at least 15 minutes. I said, "No, why should I have done that?". He replied, "These units have a 15 minute delay when the breaker is tripped. If you had left the system calling for cooling for 15 minutes, it would have reset itself.". He said that I wouldn't have known that and because the unit didn't come on, it looked as if the unit was inop. Needless to say, 15 minutes later the unit came up and is now running well.

The tech had checked the power at the quick disconnect and he did read 240 VAC, so my wiring repair did work properly. If I knew about the 15 minute delay, this would have resolved long ago.

Now I intend to contact a few folks for replacement costs for the entire HVAC system, so I can plan on a budget for them.

Thanks to everyone who replied and offered advice.