replacing a garage box

[pudgybear]

I am replacing an old fuse box with a new modern circuit breaker box in my daughter's garage, existing fuse box is a 60 amp and the replacement box is a 100 amp, my question is can i use the existing wiring that comes from the house - there is no size marking on the wire - all that is going to be used is a couple of plug circuits and a couple of over head lights, and 1 garage door opener, there is no way to replace the incoming power line WITHOUT tearing up a lot of concrete, i think i can just pull one out and put in the other!

 

[madosta]

Determine what it's protected at in the house first as you'll want to turn the power off anyways. How many wires are to the garage now? 3 or 4?

 

[rockwithjason]

If you protect the box at 60 a then there is no need to change wire. If the incoming feed is fused or breaker ed at 60 a at its originating point then just change the box out and you are fine

 

[gregtwojeeps]

I am replacing an old fuse box with a new modern circuit breaker box in my daughter's garage, existing fuse box is a 60 amp and the replacement box is a 100 amp, my question is can i use the existing wiring that comes from the house - there is no size marking on the wire - all that is going to be used is a couple of plug circuits and a couple of over head lights, and 1 garage door opener, there is no way to replace the incoming power line WITHOUT tearing up a lot of concrete, i think i can just pull one out and put in the other!

Oh, oh, later on you are going to hear from the forum members that the garage service must be brought up to code, converted to a 4 wire service as it is a sub panel, ground rods driven, inspected, yada yada, your head is going to spin with all the replies..... And actually they will be right, but we all dont have big bucks to spend and I assume you do not spend want to spend a lot on it either, or you would get the whole service updated.

That said, and do so at your own risk, just be sure the wires going from the house panel to the garage panel has no larger than a 60 amp fuses/ breaker protecting it (assuming it DOES have 60 amp rated service conductors now to the garage) . Because when you put a 100 amp panel box in the garage it will have more spaces and the next owner may come and and put BIG tools/welder/A/c whatever on the breaker box, thinking it has a 100 amp capacity in the garage . good luck.

 

[pudgybear]

So you're trying to tell me that i'll be ok IF the circuit breakers in the house are changed to 100 amps then the service wire should be ok, right? thanks gregtwojeeps

 

[2ManyProjects]

I am replacing an old fuse box with a new modern circuit breaker box in my daughter's garage, existing fuse box is a 60 amp and the replacement box is a 100 amp, my question is can i use the existing wiring that comes from the house - there is no size marking on the wire

The "short answer" is that, IF the existing feeder cable is in good general condition AND adequately protected by a properly-rated fuse or circuit breaker at its origination point (presumably in the house's main distribution panel), then it can probably continue to provide that same level of power to the new panel -- at least for awhile.

HOWEVER...

The "no markings" part is worrisome, to say the least. Do you have ANY idea what that wire really is? Do you really KNOW that it was properly sized for the job and correctly installed (particularly with respect to protecting it from damage) when it went in? This MAY be a moot point, because it presumably dates back to whenever that "fuse box" was originally installed. As such, it might not matter all that much what it started out as, after 50+ years (?) of deterioration from living underground.

So really, the question is not so much "CAN" the old feeder be used, as "Is it wise" to even attempt to do so?

- all that is going to be used is a couple of plug circuits and a couple of over head lights, and 1 garage door opener,

This leads me to ask WHY you're replacing the fuse box in the first place? If the current installation is inadequate for whatever your daughter (or Son-In-Law) wants to do with it, then in all probability so too is the feeder cable.

there is no way to replace the incoming power line WITHOUT tearing up a lot of concrete, i think i can just pull one out and put in the other!

Which is it? Can you re-pull through the existing (?) conduit, or not?

So you're trying to tell me that i'll be ok IF the circuit breakers in the house are changed to 100 amps then the service wire should be ok, right?

ABSOLUTELY NOT!!!

You can NEVER increase a breaker rating without ALSO making ABSOLUTELY CERTAIN that ALL of the wire fed from that breaker is fully capable of safely carrying that (increased) amount of current. In practice, this virtually always means replacing that wire, for reasons which are obvious if you think about it: If the wire had been adequate for more current flow when it was originally installed, a correspondingly higher-rated breaker would presumably ALSO have been installed at that time.

Note that this is EXACTLY why the half-assed "The rules don't matter, do everything on the cheap!" advice sometimes posted here (most recently by "gregtwojeeps") is not only counterproductive, it can be downright DANGEROUS.

 

[theoldwizard1]

The size of the main breaker in a sub-panel has no relationship to the size of the incoming wire or the size of the breaker in the main panel.

So you're trying to tell me that i'll be ok IF the circuit breakers in the house are changed to 100 amps then the service wire should be ok, right? thanks gregtwojeeps

ABSOLUTELY NOT !! Don't touch that breaker ! Assuming the original wiring was inspected that breaker is sized to protect the wire from the main panel to your sub-panel.

What is the size of that breaker in the main panel ? Let;s just say it is 60A. It will be possible to trip the breaker in the house without tripping any breakers in the garage, This is a nuisance, but it is the correct, safe answer.


Regarding upgrading the wire from the house to the garage, yes, you should. Mainly, because if she ever sells the house, it will likely fail an electrical inspection and you will have to do it then. At a minimum, I would install proper grounding at the garage (2 6' ground rods)

 

[gregtwojeeps]

The "short answer" is that, IF the existing feeder cable is in good general condition AND adequately protected by a properly-rated fuse or circuit breaker at its origination point (presumably in the house's main distribution panel), then it can probably continue to provide that same level of power to the new panel -- at least for awhile.

HOWEVER...

The "no markings" part is worrisome, to say the least. Do you have ANY idea what that wire really is? Do you really KNOW that it was properly sized for the job and correctly installed (particularly with respect to protecting it from damage) when it went in? This MAY be a moot point, because it presumably dates back to whenever that "fuse box" was originally installed. As such, it might not matter all that much what it started out as, after 50+ years (?) of deterioration from living underground.

So really, the question is not so much "CAN" the old feeder be used, as "Is it wise" to even attempt to do so?



This leads me to ask WHY you're replacing the fuse box in the first place? If the current installation is inadequate for whatever your daughter (or Son-In-Law) wants to do with it, then in all probability so too is the feeder cable.



Which is it? Can you re-pull through the existing (?) conduit, or not?



ABSOLUTELY NOT!!!

You can NEVER increase a breaker rating without ALSO making ABSOLUTELY CERTAIN that ALL of the wire fed from that breaker is fully capable of safely carrying that (increased) amount of current. In practice, this virtually always means replacing that wire, for reasons which are obvious if you think about it: If the wire had been adequate for more current flow when it was originally installed, a correspondingly higher-rated breaker would presumably ALSO have been installed at that time.

Note that this is EXACTLY why the half-assed "The rules don't matter, do everything on the cheap!" advice sometimes posted here (most recently by "gregtwojeeps") is not only counterproductive, it can be downright DANGEROUS.

Hello 2 Many Words,

While you were so busy typing so many words in your replies, some of your time would have been well spent comprehending what other posters have posted... For clarity, here is my post from above again and take note of the key words in blue:

" Oh, oh, later on you are going to hear from the forum members that the garage service must be brought up to code, converted to a 4 wire service as it is a sub panel, ground rods driven, inspected, yada yada, your head is going to spin with all the replies..... And actually they will be right, but we all dont have big bucks to spend and I assume you do not spend want to spend a lot on it either, or you would get the whole service updated.

That said, and do so at your own risk, just be sure the wires going from the house panel to the garage panel has no larger than a 60 amp fuses/ breaker protecting it (assuming it DOES have 60 amp rated service conductors now to the garage) . Because when you put a 100 amp panel box in the garage it will have more spaces and the next owner may come and and put BIG tools/welder/A/c whatever on the breaker box, thinking it has a 100 amp capacity in the garage . good luck.


I know you do not want to read this 2ManyWords, but try to comprehend this key point about DIY internet forums. When people post questions like the OP did, HE DOES NOT WANT TO SPEND LOT OF MONEY ON HIS DAUGHTER'S GARAGE FOR REASONS OF HIS OWN, OF WHICH HE DOES NOT HAVE TO AIR ON A FORUM. HE ASKED A SIMPLE QUESTION. IF HE WANTED A NEW SERVICE TO THE GARAGE, I FEEL SURE HE WOULD JUST HIRE A ELECTRICAL CONTRACTOR OR HE WOULD HAVE ASKED THE FORUM HOW TO INSTALL A NEW SERVICE... INSTEAD, HE ASKED IF HE COULD JUST USE THE EXISTING FEEDER, WHICH FEEDS A 60 AMP BOX.

So, slide down from your high horse, 2ManyWords, it is not a becoming attribute for one to have.

 

[2ManyProjects]

Hello 2 Many Words,

While you were so busy typing so many words in your replies, some of your time would have been well spent comprehending what other posters have posted... For clarity, here is my post from above again and take note of the key words in blue:

Stomp and sputter all you like; but the fact remains that your "words of wisdom" did indeed lead the OP to (at least tentatively -- thank Ghod he asked for confirmation!) erroneously conclude he could just replace the breaker in the main panel to effect an "instant upgrade" of his sub-panel service, with no regard to the capacity of the feeder cable itself. If that is not the very definition of "dangerous advice", I don't know what is.

I know you do not want to read this 2ManyWords, but try to comprehend this key point about DIY internet forums. When people post questions like the OP did, HE DOES NOT WANT TO SPEND LOT OF MONEY ON HIS DAUGHTER'S GARAGE FOR REASONS OF HIS OWN, OF WHICH HE DOES NOT HAVE TO AIR ON A FORUM.

"I don't want to spend the money" is NEVER an acceptable excuse for taking ad hoc shortcuts, or ignoring basic safety principles.

To suggest (as you did, even if you also gave lip service to the contrary in a somewhat "backhanded" manner) that completely ignoring the fundamental safety principles upon which the NEC is based, and/or not bothering to ground the outbuilding, and/or using an inadequate feeder cable, can EVER be OK -- and especially that "I don't want to spend the money" could EVER make any of that even the slightest bit "more OK", is irresponsible in the extreme.

 

[Speedy Petey]

Stomp and sputter all you like; but the fact remains that your "words of wisdom" did indeed lead the OP to (at least tentatively -- thank Ghod he asked for confirmation!) erroneously conclude he could just replace the breaker in the main panel to effect an "instant upgrade" of his sub-panel service, with no regard to the capacity of the feeder cable itself. If that is not the very definition of "dangerous advice", I don't know what is.



"I don't want to spend the money" is NEVER an acceptable excuse for taking ad hoc shortcuts, or ignoring basic safety principles.

To suggest (as you did, even if you also gave lip service to the contrary in a somewhat "backhanded" manner) that completely ignoring the fundamental safety principles upon which the NEC is based, and/or not bothering to ground the outbuilding, and/or using an inadequate feeder cable, can EVER be OK -- and especially that "I don't want to spend the money" could EVER make any of that even the slightest bit "more OK", is irresponsible in the extreme.

If this message board had a "Thanks" function I'd use it now.

 

[gregtwojeeps]

Stomp and sputter all you like; but the fact remains that your "words of wisdom" did indeed lead the OP to (at least tentatively -- thank Ghod he asked for confirmation!) erroneously conclude he could just replace the breaker in the main panel to effect an "instant upgrade" of his sub-panel service, with no regard to the capacity of the feeder cable itself. If that is not the very definition of "dangerous advice", I don't know what is.



"I don't want to spend the money" is NEVER an acceptable excuse for taking ad hoc shortcuts, or ignoring basic safety principles.

To suggest (as you did, even if you also gave lip service to the contrary in a somewhat "backhanded" manner) that completely ignoring the fundamental safety principles upon which the NEC is based, and/or not bothering to ground the outbuilding, and/or using an inadequate feeder cable, can EVER be OK -- and especially that "I don't want to spend the money" could EVER make any of that even the slightest bit "more OK", is irresponsible in the extreme.

My post to the OP could not have been any more direct to the point when he was asking about the service feeder breaker size. Yet the OP replies to my post and asked....

" So you're trying to tell me that i'll be ok IF the circuit breakers in the house are changed to 100 amps then the service wire should be ok, right? thanks gregtwojeeps " HUH ? How did the OP derive this from my post above ??

I agree with you TMP on doing electrical projects to code, never was a doubt about that. But not all people have the money to bring their project "up to code" which is most likely the case in this thread, or the OP would not be asking on a internet forum about their project. ....

But I think this thread should be a lesson to all the readers here. If someone is asking about doing a electrical project on this forum, the person that is responding to their inquiry, " Does not know the electrical skill level or in general, the mental aptitude of the OP' ...

So in knowing this, all the people giving out advice on a DIY electrical forum are subject to scrutiny. If I was not knowledgable of electrical work, how do I know if I am getting the correct advice from TMP ? Or anyone else on here for that matter ? Better yet, why do people give advice to someone doing electrical work, that has to ask questions about their project on a forum ? ...

Harsh statement ? I dont think so. Look at this thread. The person was told his plan of action was NOT the right way by more posters than just I. Yet his next question was after reading the replies was, "Is it O.K. to increase the existing breaker protecting the existing 60 amp service to his daughter's garage to 100 amps ?? ! Do What !! ??!!

I have learned my lesson here about DIY electrical forums so, I will not be returning ( try to keep down the applause please) . ....

I think anyone replying on DIY electrical forums should make themselves aware of the fact, they may be giving info out to someone that is not capable of handling it. There always exists the "possibility " that the use of the info given out on a forum and used by the person asking for advice could get the the advice taker killed, injured or have property damage in trying to impelment the forum's advice. ....

And also, is their potential litigation risks for the advice givers on a electrical forum ? What if someone gets hurt while doing a project advised by the forum member, and they got hurt taking GOOD advice ? Yet, the user (person asking for help) was NOT qualified to be doing the work advised ? ...

There may be a, "freedom of liability clause" for all posters somewhere in the TOS for this site, I dont know. But I learned a long time ago, if enough money is spent on a powerful attorney, NO ONE can sign away their right to sue.

Bye ya'll Happy New Year !