Trying to understand old edison fuse box at my parents apartment - Page 1
Forum section: electronics / beginners

author: echo_jey
author_rank: Contributor
timestamp: June 10, 2014, 07:04:06 pm
content: I have no idea what is the total amp of this box. from the box diagram I'm not able to understand any. from top to bottom of the fuse box, first row has two edition plug fuse, left for left side of house(outlets and lights) , right side ( in picture removed plug hole) for right side of house(including outlets and lights and refrigerator)I'm trying to put 15A portable Air conditioner on right side outlet. when I tried last week one of the other outlet on the same line got burned and short circuit. Apartment surrendent replaced the outlet.Could someone please explain the AWG wire guide in the fuse panel(picture attached)? also can I use 15A AC on the outlet?Also what amp rate fuse should I use on top 2 fuse plug holes?Can I use mini breaker of 15A or 20A 'p' type edison plug?http://www.amazon.com/Bussmann-BP-MB-20-Circuit-Breaker/dp/B000GAS1GY

author: echo_jey
author_rank: Contributor
timestamp: June 10, 2014, 07:06:56 pm
content: clear diagram picture in large size.

author: denelec
author_rank: Regular Contributor
timestamp: June 10, 2014, 09:22:33 pm
content: The wire guide seems to indicate a range of usable wire gauges with the panel, not the actual gauges used.Usually, 120V outlets and lighting are wired with #14AWG copper wire.You must use 15A fuse or breaker on these circuits.For an air conditioner, you could use a type "D" time delay fuse.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: June 10, 2014, 09:38:49 pm
content: Some missing info , pictures etc. , seems like there is some of the box not in the picture ?Back off and get the hole box in the picture and any boxes in the area , I do not see the main fuse ?The diagram show more positions than the picture shows , picture from father away ! hole unit .You need to get an electrician , because with your question , it sounds like your are not qualified to work on this ?The rating for each fuse position is mainly established by the gauge of wire between the fuse & outlets - load .Then there are inserts to each fuse position that restrict what fuse can be screwed in [ to keep you from putting lets say a 30 amp fuse is a circuit meant for 15 amps ] .YOU CAN NOT / SHOULD NOT TRY TO CHANGE THE RATING OF ANY FUSE POSITION !With pictures of all , we should be able to find the main fuse / fuses and the adding up of those indicate the load for that box .

author: pickle9000
author_rank: Super Contributor
timestamp: June 10, 2014, 09:52:38 pm
content: You will need to check the wire gauge to be safe. Check the outlet in the wall or pull the panel cover. You also need to know of any other items on that circuit. 15 amps is probably the max you can run but if you have anything else on that branch then you will just risk popping the breaker. If you put in an oversize breaker you risk melting the copper in the wall and starting a fire.You may want to check the stove in the apartment, they often have a 15 amp socket on them, if electric. Get a heavy gauge extension cord and use that. Much safer and less trouble, I know it's ugly.

author: Clear as mud
author_rank: Regular Contributor
timestamp: June 10, 2014, 10:05:02 pm
content: Older panels like that sometimes didn't have a main fuse or breaker. I think that is the case, with this panel. In the final, clearer picture that you posted, you can just barely see, below the bottom right box where it says "AMPS," the manufacturer has stamped "100" on the label. If I'm reading that correctly, you just need to make sure that the total of all fuses on each side of the box does not exceed 100 amps.Also, it is correct that you should look at what wire size is actually connected, to size the fuses. If they wired the house with all 14-gauge wire, then there should not be fuses of greater rating than 15 amps in the box. Often, in an older house, you will find that some of them have been replaced with 20 or 30 amp fuses, but it is really not safe to operate it like that. That could be the cause for the burned up outlet when you plugged in the new air conditioning load.It looks like there is a non-used circuit (the one with no fuse in it) near the top of your picture. You might try to see if you can run a new circuit from that to your air conditioner location. But because it looks like there is no main breaker, you would have to do the work with almost all parts inside the panel live. I would recommend hiring a qualified electrician. Or, as someone else suggested, run an extension cord from another circuit that isn't already loaded too much. But make sure the extension cord is thick enough. 12-gauge wire is generally thick enough to avoid having too much voltage drop, but it depends on the length.

author: echo_jey
author_rank: Contributor
timestamp: June 10, 2014, 11:58:52 pm
content: sorry, here is the main fuse ( picture attached).

author: dfmischler
author_rank: Frequent Contributor
timestamp: June 11, 2014, 12:03:16 am
content: Quote from: Clear as mud on June 10, 2014, 10:05:02 pmNo. There is probably a fused disconnect at the service entrance. The fuses are intended to protect the wires that leave the panel, not the panel itself.QuoteMe, too. Especially if you don't understand it well enough to do a safe job.

author: echo_jey
author_rank: Contributor
timestamp: June 11, 2014, 12:37:05 am
content: Quote from: Clear as mud on June 10, 2014, 10:05:02 pmWow you spotted that 100 amp total which I never noticed before. That hole was the main reason for this post since this hole blowing every fuse I tried to put in, later I reported to their apartment superintendent (self claimed electrical-electronics engineer in Kenya) he shown up and he replaced the outlet that has burned due to short circuit , also he and I agreed thats the reason for that hole not accepting any fuse. later he put new fuse and now everything works.also he changed another recently replaced outlet with new receptacle, since I shown him one portion of the outlet has yellow marks. these all outlets are connected to that 'hole' fuse. also the burnt outlet is not the one that I connected AC ( I connected AC to the adjacent burned outlet which is 4 feet apart on the same wall).I forgot to check whats the new fuse amp rate he put on that hole, but he advised me that I can use max 20amp fuse. still I'm not quite understand whether I can use my 15amp ac or not. so now the question is what gauge of wires running inside the wall, for argument sake if the wire capable of carrying 20Amp then I won't have any problem in connecting my 15Amp AC? also is there any easy way to tell what gauge wires used behind the walls using multimeter? I don't think I can read any label on that wire since its old apartment.Also I'm planning to use edison plug mini breaker, but its only available in P type in 15Amp and 20Amp, this is very economical considering we already gone through 10 fuses.http://www.amazon.com/Bussmann-BP-MB-20-Circuit-Breaker/dp/B000GAS1GY

author: ignator
author_rank: Regular Contributor
timestamp: June 11, 2014, 02:52:21 am
content: Quote from: echo_jey onTodayat 07:37:05 PMRemove the cover plate that allows the access to the wires that connect to terminals for each of the fuses. You can inspect the wire size at this point. Should be very easy to tell if they are 14 or 12 AWG. It does appear the someone painted over your panels, so you will disturb the paint.Now it will be trust that the size of wire in the panel is the same size all the way through the wire path to the outlets.

author: Clear as mud
author_rank: Regular Contributor
timestamp: June 11, 2014, 04:06:25 am
content: Quote from: ignator on June 11, 2014, 02:52:21 amBut in the case where you have absolutely no experience working with these types of wire, it's not so easy. You will need to acquire a short length of each gauge of wire, to compare with. 14 and 12 are very different, and the odd-numbered ones around them are never used, so you really ought to find one or the other gauge hooked to each general-purpose circuit in your panel. If for example, you buy 1 foot of 14 AWG and 1 foot of 12 AWG at a hardware store, then you will have something to compare with if you take the panel cover off and take a look. 12 is the bigger size and can safely be used with a 20 amp breaker or fuse.The National Electrical Code generally specifies that the continuous load on the circuit should be no more than 80 percent of the fuse rating, or 16 amps for a 20 amp circuit, so yes you could use the 15-amp air conditioner on a 20-amp circuit. Although, as you already found out, all the load may pass through one or more 15-amp rated outlets, and especially in the case where those are old and have been subjected to repeated loads at or near their maximum rating, they can burn up.

author: echo_jey
author_rank: Contributor
timestamp: June 11, 2014, 04:09:57 am
content: Quote from: ignator on June 11, 2014, 02:52:21 amis it same as if I remove receptacle and check the wire size? When I go parents house I will take picture and post here. even in new houses they use 14 ? in my opinion its better to use 12AWG and let the home owner to decide what plug he want to use for what appliance.

author: echo_jey
author_rank: Contributor
timestamp: June 11, 2014, 04:15:58 am
content: Quote from: Clear as mud on June 11, 2014, 04:06:25 amThanks for the advice, darn, I just threw out the wires that superintendent cut while putting new receptacle. I'm going to replace another loose receptacle myself and that time I'm going to cut a piece and run to HomeDepot to compare.

author: Clear as mud
author_rank: Regular Contributor
timestamp: June 11, 2014, 04:23:12 am
content: You can check the wire size at the outlet or at the panel, but as ignator already pointed out, in either case you have to make the assumption that the same wire size is used throughout. That may or may not be true. In my house which was built in 1935, there were originally only a couple of circuits powering most of the house, and they used 12 AWG for the main run to the panel, but branched off that with 14 AWG.Even in new houses, 14 is sometimes used. It depends a lot on which electrician you hire, and what is typical in your area. Around here (Oklahoma), 12 seems to be most common, but in other areas of the country they commonly use 14 gauge and all 15-amp circuits.

author: SL4P
author_rank: Super Contributor
timestamp: June 11, 2014, 10:26:51 am
content: Following on from other contributors...You don't sound like you are capable of doing this job safely - at allNo insurance, fire, death - all cheaper options.

author: ignator
author_rank: Regular Contributor
timestamp: June 11, 2014, 03:00:10 pm
content: Quote from: ignator onYesterdayat 09:52:21 PMQuote from: echo_jey onYesterdayat 11:09:57 PMYes same if you check wire size at receptacle.If you were wiring your OWN house you might do this (I've only done this in workshop). But $ drives to cheaper solutions, as even with custom built, electrician selected is low bidder, and most home builders just need code compliant construction, not excessive, and 14-2 NM wire is cheaper then 12-2 NM (Non Metallic, referring to sheathing of the cable Romex is a trade mark name sometimes used in US). There's no price difference between the fuses or circuit breakers. Same with 15 vs 20 amp outlet receptacles. (at least here in the States). And most consumer loads are lamps or small appliances, so 20 amp is generally not a high usage power requirement. Most homes have central air conditioning, so having 20 amp or 240V outlet for a window AC use is not needed. Apartments are a whole different thing. Unless specified by drawing print, you get minimum.