Tapping Into Subpanel Feed To Detached Building


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Old 10-12-09, 12:43 PM
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Tapping Into Subpanel Feed To Detached Building

I have a 30 amp breaker in my main service entrance in the house that feeds a 30 amp subpanel in my detached garage. I asked an electrician if it was feasable to tap into that line where it runs through the basement (then onto the garage). He said it could be done, but didn't give too many details.

I would like to feed a couple of 3 foot baseboard heaters from this line as it is easily accesible. Running a new line from the main panel would be a real chore as the part of the house it is located in is on slab, so no under floar access. Running through the attic would be treachorous as I had a foot of insulation blown in.

Here is what I have now:





Proposed:





So, I am wondering if can join the wires at the new panel to continue to the garage, or if I should continue the run to the garage with another 30 amp breaker in the new panel. Or is none of this possible.


P.S. I have shown in my diagram that the ground wire from the main panel is running to the garage panel, but this may not be so. I realize that detached buildings need a seperate ground, but this house is 50 years old so I will see how they did it way back when.


P.S. P.S. I live in British Columbia, Canada, so U.S. codes won't apply.
 
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Old 10-12-09, 01:30 PM
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what wattage and voltage are the heaters?
 
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Old 10-12-09, 01:39 PM
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What is currently powered by the subpanel in the garage and what wattage heaters do you want to add?

A 30A feeder is already pretty small, and I'm worried that the wires can't handle the load even if you can do the basement tap. This feeder would max out at 5700W of heaters with no room to power anything else in the garage.
 
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Old 10-12-09, 06:37 PM
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I want to add 2 baseboard heaters to this circuit. They are 240 volt, 750 watts and 3 amps each. So, a total of 6 amps.

Currently the subpanel is powering 8 wall outlets and 12 8' flourescent lamps. I should mention that this is just for the garage. I have a seperate 60 amp service for my compressor and welder in my workshop.

One other thing that I discovered. The wire from the main panel to the junction box in the basement (where it feeds into underground conduit) is "8awg Vynilex type NMD7 Nylon 90* 300 Volts". So I am wondering if I can swap out the 30 amp breaker in the main panel with a 40 amp, and feed the garage with a 30 amp breaker in the new panel. The wire goes to 10awg in the junction box.


Speaking of junction boxes, this is what I found when I removed the electrical tape from one of the connections. How stupid is that!!







 
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Old 10-12-09, 09:38 PM
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Why are you calling that connection stupid? Using copper barrel crimps is a perfectly acceptable method as long as the wires are twisted before crimping as was obviously done and the proper crimping tool was used as is also obvious. I would have probably cut off the excess wire from the outboard end of the barrel crimp but as long as it was properly taped it is A-OK.
 
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Old 10-12-09, 10:35 PM
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This is " A-OK "? I think not. Would an electrical inspector pass this? I hope not. Along with the wires scraping on the edges of the sharp metal conduit when Bubbah the electrician stuffs the wires back into the box?


If this passes code I will throw all my books away and do things my way. My way being I can sleep at night knowing nothing I did will burn my house down.


I will use electrical tape on speaker wire, but not on high voltage.







 
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Old 10-12-09, 11:20 PM
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Originally Posted by bunsorama View Post
This is " A-OK "? I think not. Would an electrical inspector pass this? I hope not. Along with the wires scraping on the edges of the sharp metal conduit when Bubbah the electrician stuffs the wires back into the box?


If this passes code I will throw all my books away and do things my way. My way being I can sleep at night knowing nothing I did will burn my house down.


I will use electrical tape on speaker wire, but not on high voltage.








if you use voltage rated tape, what is the problem?. That is exactly what I use on a split bolt connection although I also use 3M 130C which is a thicker tape but ultimately, the metal is insulated with 600 volt rated tape.
 
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Old 10-13-09, 06:40 AM
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Depending on the amp draw of garage equipment another subpanel should be ok with 15a breakers for the heaters. You will though probably have to add a Jbox to splice on extra cable.

My electric books say to twist, solder, wrap with rubber tape then friction tape. Over the years ways change but it doesn't mean they were bad,. Oh and the soldering iron wasn't electric. It was heated in a gasoline blowtorch.
 
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Old 10-13-09, 08:04 AM
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Originally Posted by bunsorama View Post
This is " A-OK "? I think not. Would an electrical inspector pass this? I hope not.
Electricians make crimped or bolted and taped connections all the time. It is legal by the code as long as you use the correct materials, which it appears your former electrician did. Once you get above #6 there really is no other way to do it unless you buy Polaris connectors at $40/ea.

Along with the wires scraping on the edges of the sharp metal conduit when Bubbah the electrician stuffs the wires back into the box?
The picture shows no evidence of damaged wires or improper box fill.

If this passes code I will throw all my books away and do things my way. My way being I can sleep at night knowing nothing I did will burn my house down.
It's not like wirenuts are magical -- they can come loose, melt and cause a fire too. Every splice is a potential failure point.

I want to add 2 baseboard heaters to this circuit. They are 240 volt, 750 watts and 3 amps each. So, a total of 6 amps.
I think it should be fine as long as the load in the garage doesn't over do it. Install a small subpanel in the basement and continue out to the garage from that panel with a 30A or even a 20A double-pole breaker. Keep your neutrals and grounds separate in the new sub.
 
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Old 10-13-09, 09:53 PM
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Thanks for all yor replies. Appears I overreacted regarding the electrical tape covered connections. As 'Furd' said, it would be better if the former electrician had cut off the loose strands at the end of the clamp, therefore making the end 'blunt' so none of the wires could pierce the tape.


As far as wirenuts are concerned, I'm not crazy about them either. Undertightened or overtightened makes for bad connections, especially when joining solid to stranded.


So I had this great idea for a junction box that uses buss bars with screw connections, like a service panel or subpanel, except without the breakers. Or does something like this already exsist?



 
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Old 10-13-09, 10:19 PM
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why don't you just use these:

 
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Old 10-13-09, 10:51 PM
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^

And these are called....???




P.S. What is a 'J' Box?
 
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Old 10-14-09, 07:39 AM
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P.S. What is a 'J' Box?
A Jbox. is a Junction box


,,,,
 
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Old 10-14-09, 08:21 AM
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The picture is of Polaris brand connectors. Most of these types of connectors are not stocked at hardware and big box stores, but if you go to an electrical supply house they should have several different types of connectors you can choose from. There are devices similar to your drawing usually sold as motor connection blocks. You can also use insulated crimps which are basically a copper barrel with a plastic or rubber sleeve that slides over instead of tape.
 
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Old 10-14-09, 12:25 PM
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I have used these in the past and feel 'comfortable' doing so. Wires are secured by a setscrew, then the plastic cap is threaded on. They can handle 10 gauge wire. Any reasons not to use these?



 
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Old 10-14-09, 05:00 PM
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That wire nut you mention that I use that once a while but not very often normally I used wirenut or " choc block " aka 3M connectors depending on which area I am in { the French use the latter while the USA / Cananda use the wirenut/marrte those are good until you get up to #6{ 16mm˛} but once get larger or large number of connections then I used Polaris block connector or choc connector.

Merci,Marc
 
 

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