Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

can you jumper both legs of a fuse panel using one 110v wire?

can you jumper both legs of a fuse panel using one 110v wire?

Reply

  #1  
Old 10-26-10, 07:40 PM
N
Member
Thread Starter
Join Date: Oct 2010
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Exclamation can you jumper both legs of a fuse panel using one 110v wire?

By connecting both legs of the sub panel to one 110v wire will it draw too many amps and melt my main line or be unsafe in any way?

*note: there are only 110v devices hooked up in the garage, no 220v

I purchased a foreclosed home and the garage is wired up from my main panel in my house via a 10-2 w/ ground wire to a sub panel in the garage. Every wire in the fuse panel completely bypassed the sub panel and connected directly to the incoming hot wire (i know i know!)

so I did a little rewiring and I need to make sure its safe before I melt the main line coming in. here is the new configuration:

From house main panel (60amp breaker) to garage sub panel
10-2 w/ ground (only 1 hot coming in to the garage)
  • Black wire = 110 hot
  • White wire = neutral
  • Ground = ground

The black wire is connected to the left leg of the sub panel. There is a 10guage jumper from where the black wire meets the left leg that jumpers over to the right leg. This makes both legs of the sub panel hot @ 110. Here is crude picture of the current configuration:



http://i52. tiny pic . com/2cehy05.jpg <-- take out the spaces
 
  #2  
Old 10-26-10, 08:19 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Please host your picture on some site other than tinypic. This forum does not allow tinypic.

You use the terms circuit breaker and fuse panel, which is it or do you have both? If both fuses and circuit breakers WHERE are the circuit breakers and where are the fuses.

What kind of "10-2 w/ground CABLE (not wire) do you have and how is it installed between the garage and the house? Is the garage a separate building or is it attached to the house? Does the cable have "type UF" printed or embossed on the outer jacket?

A sixty ampere circuit breaker is too large to feed a #10 conductor. #10 has a maximum Ampacity of 30 amperes except in some very specific and rare cases.

Under some circumstances a 120 (not 110) volt circuit MAY be connected to both legs of a single-phase circuit breaker or fuse panel but not in the manner that you described.
 
  #3  
Old 10-26-10, 08:30 PM
N
Member
Thread Starter
Join Date: Oct 2010
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Thank you for your response Furd.

I checked everything again, did some research, and I believe everything is up to code.

My house has a breaker panel with a 40 amp breaker. The 10-2 w/ ground is UF-B rated @ 90c @ 600v. According to my research, a 10-2 @ 90c can support 40 amps.


and to answer my own question, by connecting both legs of a fuse panel (yes my sub panel in the garage is the old screw in style fuse panel) to the one 110 wire will allow up to the amps the other end of the the wire allows. Therefore, if the house end allows 40 amps and the wire supports 40 amps, then the fuse panel in my garage can handle up to 40 amps before the house breaker 'breaks'.

wordy yes. hah


What image site can I use to post images for future reference?
 
  #4  
Old 10-26-10, 08:37 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,581
Received 13 Votes on 11 Posts
My house has a breaker panel with a 40 amp breaker. The 10-2 w/ ground is UF-B rated @ 90c @ 600v. According to my research, a 10-2 @ 90c can support 40 amps.
#10 is only rated for 30a not 40a. Code requires using the 60 column. Does the fuse panel have an isolated neutral bus and separate bonded ground bar? Do you have a ground rod at the subpanel?
 
  #5  
Old 10-26-10, 08:49 PM
N
Member
Thread Starter
Join Date: Oct 2010
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Correct on the #10 only being rated for 30a. Through research i've found that 90 can handle 40amp (dont quote me on this, just read it somewhere, the internet is always right! hah).

Old house, old stuff. The breaker panel in the house does not have a seperate bonded ground bar and there is a ground rod on both the main panel and sub panel.
 
  #6  
Old 10-26-10, 08:52 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,581
Received 13 Votes on 11 Posts
The breaker panel in the house does not have a seperate bonded
That is correct for the main panel. Only the subpanel, fuse box, needs ground and neutral separate.
 
  #7  
Old 10-26-10, 08:58 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
The 90 degree C. column is used only for derating purposes. Cables ( a cable is defined as more than one conductor with an overall covering or sheath) are almost always limited to the 60 degree C. column. By code size #14, #12 and #10 are limited to 15, 20 and 30 amperes respectively under all conditions.

By using the fused panel you have made the #10 cable a "feeder" rather than a branch circuit. This means that you may have a combination of less than six possible disconnects in the sub-panel without having a main disconnect. If this sub-panel has room for more than six fuses then it MUST be preceded by a disconnect switch. (It is possible that since it is a fuse panel rather than circuit breakers it must have a disconnect switch regardless of the number of fuses.) The simplest disconnect would be a 30 ampere unfused "air conditioner" disconnect, about ten or fifteen dollars at the big box megamart homecenter. You will need to have short pieces of wire (pigtails) from each main lug in the sub-panel and wire-nut them to the black wire from the feeder cable (or disconnect) with the white wire going to the neutral bus. You will need a separate equipment ground bus (a few bucks at the homecenter) bolted to the sup-panel and the "bond" between the neutral bus and the box itself removed. This "bond" is probably a screw through the neutral bus to the metal of the box. You need at least a single eight foot long ground rod at the site of the sub-panel connected with not less than #6 copper wire. If the soil conditions are not ideal (usually damp a foot or so below grade) then you need a second ground rod a minimum of six feet from the first. The two rods need to be connected together and the connections need to made with an "acorn" type clamp. The #6 copper from the rod(s) connects to the equipment ground bus in the sub-panel.

Good sites for hosting pictures are photobucket.com, villagephotos.com and imageshack.com All have free accounts although you may have to register which you can do with an assumed name.
 
  #8  
Old 10-26-10, 09:11 PM
N
Member
Thread Starter
Join Date: Oct 2010
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Thank you for your insight ray. Here is my current configuration:



http://img818.imageshack.us/img818/6585/68781469.jpg
 
  #9  
Old 10-26-10, 09:22 PM
N
Member
Thread Starter
Join Date: Oct 2010
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
alright Furd, since I really dont want to spend money if i dont have to, would the first scenerio (drawing) work to keep the Amp rating under 30 or should I just not worry about going over 30 since I have UF-B wire?

Theoretically keep amp under 30


Current existing configuration
 
  #10  
Old 10-26-10, 10:07 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,581
Received 13 Votes on 11 Posts
It is the feeder from the house that must be protected by a 30 amp OCPD so you must have a 30a breaker at the house. Is one of the black wires supposed to be green/bare? All pictures are wrong because they seem to show a combined neutral ground at the fuse box.

Also most bus line connections aren't designed to be double lugged as shown in the first image. Going from load side of a fuse holder to line in on the other bus as shown in other images would be OK.
 
  #11  
Old 10-26-10, 10:26 PM
N
Member
Thread Starter
Join Date: Oct 2010
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
first off i'd like to thank everyone for posting. every little bit of information will help me understand the electrician better when he arrives.

I'd also like to add that this is only temporary wiring until the electrician does what he needs to do to bring it all up to code.

The only thing that runs constant in the garage is 1 fridge and I have no heavy duty power tools that will even draw anywhere near 30 amps.

so for the next couple weeks......



The bottom picture of the 2 is the current wiring diagram. The ground and neutral from the house, the wire to the grounding rod, and the nuetrals/grounds for every circuit all connect to the same grounding bar. This is a very old (i'd say from the '50s) and small sub panel with no room to add a bonded ground bar.

In your opinion, should I rewire the box to the top picture or leave it hooked up like the bottom picture?
 
  #12  
Old 10-26-10, 10:45 PM
F
Member
Join Date: Mar 2006
Location: NE Wis / Paris France{ In France for now }
Posts: 4,807
Received 0 Votes on 0 Posts
If your electrician is comming to deal with service size and other related items to bring up the code and talk to him about the garage subpanel IMO that part you may need to bring it up to the code anyway due the exsting set up is not really safe at all due you have both netural et grounding conductor in the same bussbar.

I do understand that you have old plug fuse box there but as soon the electrician start work on it it good time to ditch that one and run a new one and you will not have to worry about anything.

Most subpanel I install typically are 50 amp size but few will have larger only if the owner of that place will have much bigger powertools etc etc.

Per modern code all the 120 volt garge circuit have to be RCD { GFCI } no extempts { but check with your local codes for latest info if any change }


If you have more question just ask us we will reply to ya

Merci,.
Marc
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: