I just looked at a friend's fuse panel yesterday... It has a 60A main fuse that feeds the bus bars for the plug-in fuses, and tapped from the main fuse line side (not load or post-fuse side) are a 40A stove circuit (cartridge fuse) and a 30A air conditioner circuit (cartridge fuse). To me, it appears you can be drawing considerably more current than the service conductors were meant to handle, which in this case is 60A. Why was it ever acceptable to have this setup? Am I missing something? This is a General Switch fusebox installed in 1973, and this box does not appear to have been altered.
Overfusing - why was this allowed???
- Thread starter jimmyh
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Re: Overfusing - why was this allowed???
What size are the service entrance conductors? I'm willing to bet this is a 100 amp service. The General Fuse Box is most probably rated at 100 amps, the second set of pull out line side is internally bugged to the main lugs ahead of the 60 amp fuses. This is not any different than the old split bus panels that fed the bottom half of the panel from a 60 amp 2 pole breaker.
What size are the service entrance conductors? I'm willing to bet this is a 100 amp service. The General Fuse Box is most probably rated at 100 amps, the second set of pull out line side is internally bugged to the main lugs ahead of the 60 amp fuses. This is not any different than the old split bus panels that fed the bottom half of the panel from a 60 amp 2 pole breaker.
GG
Senior Member
- Location
- Ft.Worth, T.X.
Re: Overfusing - why was this allowed???
Maybe the stove and AC were added sometime later after the original panel was installed, and whoever installed them did not take into consideration the fact that they might overload the service conductors?
Maybe the stove and AC were added sometime later after the original panel was installed, and whoever installed them did not take into consideration the fact that they might overload the service conductors?
jwelectric
Senior Member
- Location
- North Carolina
Re: Overfusing - why was this allowed???
The six disconnect rule found in 230.71 (230-71 back then) allows this type of installation.
This service passes
The six disconnect rule found in 230.71 (230-71 back then) allows this type of installation.
This service passes
rick hart
Senior Member
- Location
- Dallas Texas
Re: Overfusing - why was this allowed???
With 60A main fuses, this is a 60A service; you would not have a main fuse and branch fuses within the same box..... I think. Unless you are replacing the main fuses, you don't have an overload regardless of the rating of any other fuses present. It's not a good set up but appears to be just barely legal from the information provided.
If this guy is a friend, a 100A service would be a true act of friendship.
With 60A main fuses, this is a 60A service; you would not have a main fuse and branch fuses within the same box..... I think. Unless you are replacing the main fuses, you don't have an overload regardless of the rating of any other fuses present. It's not a good set up but appears to be just barely legal from the information provided.
If this guy is a friend, a 100A service would be a true act of friendship.
rick hart
Senior Member
- Location
- Dallas Texas
Re: Overfusing - why was this allowed???
Guilty of not reading close once again!
With the two other fuse boxes tapped on the line side of the main fuse, I doubt this would be even barely legal- the lugs on the line side would need to be listed for multiple conductors.
Guilty of not reading close once again!
With the two other fuse boxes tapped on the line side of the main fuse, I doubt this would be even barely legal- the lugs on the line side would need to be listed for multiple conductors.
Re: Overfusing - why was this allowed???
Rick
This is an internal connection common on most fuse boxes manufactured in the 60's and 70's. These are indead rated at and installed as 100 amp service equipment packages. Again this is not any different than the split bus panel configurations and is perfectly legal using the six disconnect rule. Check the manufacturers spec and you will fgind it is 100 amp rated.
Rick
This is an internal connection common on most fuse boxes manufactured in the 60's and 70's. These are indead rated at and installed as 100 amp service equipment packages. Again this is not any different than the split bus panel configurations and is perfectly legal using the six disconnect rule. Check the manufacturers spec and you will fgind it is 100 amp rated.
jwelectric
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- North Carolina
Re: Overfusing - why was this allowed???
Gene is correct with his statement.
As outlined above, article 230.71 has been unchanged over the past thirty years
Gene is correct with his statement.
As outlined above, article 230.71 has been unchanged over the past thirty years
Re: Overfusing - why was this allowed???
To respond to the various questions/comments:
Gene: Size of service conductors appears to be #6 AL. I need to get a better look to be sure, but they don't appear to be the #2 AL they need to be for 100A.
Physis: As for disconnects, you'd effectively have three? the 60A for the bus, 40A for the stove, 30A for A/C.
GG: Thinking that this was the case for the A/C, but my friend who's owned the place since new says "no". Another reason I think that your guess is right is that the feed to the line side of the 30A fuse is only #10 CU. This is definitely not to code, seeing as you have no upstream circuit protection, and basically go from the service conductor to the #10.
JWElectric (1st): Agree? this meets the six disconnect rule.
Rick Hart: 100A would make me happy too. Unfortunately, I have NO idea how the service was run. Picture a long condo complex, meters on one side, my friend's condo on the other. The service appears to neither be run in conduit in the walls (since it's not individual conductors, but service entrance cable with no sign of any conduit), or run to the exterior and run underground (due to the orientation and height the cable leaves the panel, relative to the exterior of the condo). I'm thinking that it may have been run through the walls through the other adjoining condos. I do have to admit I have not looked at the meter bank, but I have a sneaking suspicion that there are no safety disconnects at the meters either.
Gene/Jwelectric (2nd): The panel is truly rated for 100A, but what I'm not seeing is? if the cable isn't rated for 100A, and you effectively have 60A, 40A, and 30A loads, how is this allowable?
Physis: Exactly. The way this box is wired, the service entrance conductor gets split between a 60A main fuse (that feeds the plug-in fuses below it), a 40A stove fuse, and a 30A A/C fuse. Thus, the stove and A/C fuses are not fed by the 60A main? but are tapped off the lugs on the line side of the 60A main.
To respond to the various questions/comments:
Gene: Size of service conductors appears to be #6 AL. I need to get a better look to be sure, but they don't appear to be the #2 AL they need to be for 100A.
Physis: As for disconnects, you'd effectively have three? the 60A for the bus, 40A for the stove, 30A for A/C.
GG: Thinking that this was the case for the A/C, but my friend who's owned the place since new says "no". Another reason I think that your guess is right is that the feed to the line side of the 30A fuse is only #10 CU. This is definitely not to code, seeing as you have no upstream circuit protection, and basically go from the service conductor to the #10.
JWElectric (1st): Agree? this meets the six disconnect rule.
Rick Hart: 100A would make me happy too. Unfortunately, I have NO idea how the service was run. Picture a long condo complex, meters on one side, my friend's condo on the other. The service appears to neither be run in conduit in the walls (since it's not individual conductors, but service entrance cable with no sign of any conduit), or run to the exterior and run underground (due to the orientation and height the cable leaves the panel, relative to the exterior of the condo). I'm thinking that it may have been run through the walls through the other adjoining condos. I do have to admit I have not looked at the meter bank, but I have a sneaking suspicion that there are no safety disconnects at the meters either.
Gene/Jwelectric (2nd): The panel is truly rated for 100A, but what I'm not seeing is? if the cable isn't rated for 100A, and you effectively have 60A, 40A, and 30A loads, how is this allowable?
Physis: Exactly. The way this box is wired, the service entrance conductor gets split between a 60A main fuse (that feeds the plug-in fuses below it), a 40A stove fuse, and a 30A A/C fuse. Thus, the stove and A/C fuses are not fed by the 60A main? but are tapped off the lugs on the line side of the 60A main.
jwelectric
Senior Member
- Location
- North Carolina
Re: Overfusing - why was this allowed???
You are almost correct Sam.
The range and air conditioner are part of the six disconnecting rule. Or in other words they are part of the Main.
As outlined in the original post there are three disconnects that are part of the main, the six disconnect rule found in 230.71 or 230-71 in the1971 cycle.
You are almost correct Sam.
The range and air conditioner are part of the six disconnecting rule. Or in other words they are part of the Main.
As outlined in the original post there are three disconnects that are part of the main, the six disconnect rule found in 230.71 or 230-71 in the1971 cycle.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: Overfusing - why was this allowed???
As I read 230.71, you don't get to take credit for fuses as the "up to six" disconnecting means. It talks about breakers and switches, but not fuses. How would this change the situation, if at all?
As I read 230.71, you don't get to take credit for fuses as the "up to six" disconnecting means. It talks about breakers and switches, but not fuses. How would this change the situation, if at all?
jwelectric
Senior Member
- Location
- North Carolina
Re: Overfusing - why was this allowed???
Good question Charlie.
The use of a fuse in a disconnect could be a hot trough with six fused knife disconnects as is commonly done.
When I first started as a helper and we did a service upgrade which was rare we was upgrading from a 60 amp service to a 100 amp service.
230-31 of the 1975 cycle Optional Calculation for Additional Loads in Existing Single-Family Dwelling Occupancy. For an existing single-family dwelling occupancy presently being served by an existing 115/230 volt or 120/208 3- wire 60-ampere service???.
What is described by the original post was not uncommon in the 60s and 70s
edited to add: this house was built in 1973 and was under the 1971 cycle
[ July 26, 2005, 04:21 PM: Message edited by: jwelectric ]
Good question Charlie.
The use of a fuse in a disconnect could be a hot trough with six fused knife disconnects as is commonly done.
When I first started as a helper and we did a service upgrade which was rare we was upgrading from a 60 amp service to a 100 amp service.
230-31 of the 1975 cycle Optional Calculation for Additional Loads in Existing Single-Family Dwelling Occupancy. For an existing single-family dwelling occupancy presently being served by an existing 115/230 volt or 120/208 3- wire 60-ampere service???.
What is described by the original post was not uncommon in the 60s and 70s
edited to add: this house was built in 1973 and was under the 1971 cycle
[ July 26, 2005, 04:21 PM: Message edited by: jwelectric ]
- Location
- Massachusetts
Re: Overfusing - why was this allowed???
This is also allowed if the calculated load is less than the rating of the service conductors.
Re: Overfusing - why was this allowed???
I've worked on plenty of these myself,Main,Range,and 4. that is what we used to call them.
The fuses are in a pullout set up,you could turn it upside down and reinstall the pullout and in a small area it would say 'OFF' turn it around and 'On'
Rating was: 100amp. ,Pullout's were Disconnecting Means
frank
I've worked on plenty of these myself,Main,Range,and 4. that is what we used to call them.
The fuses are in a pullout set up,you could turn it upside down and reinstall the pullout and in a small area it would say 'OFF' turn it around and 'On'
Rating was: 100amp. ,Pullout's were Disconnecting Means
frank
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