Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Shack on March 12, 2016, 05:40:23 pm
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I thought it was a stupid question, but not sure after a search....Can I put fuse on neutral and switch on hot to eliminate wire nut or shrink wrap, or should they both be on hot?
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I believe it's considered good practice to put them both on hot.
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ok, thats how I got it now....power cord still unattached......would be neater to put fuse on one and on/off switch on other
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> would be neater to put fuse on one and on/off switch on other
That's how the old stuff was ALWAYS wired. Neat, simple.
Since you do NOT really know which wire is "neutral" (and neither is a true neutral), you treat them the same and insulate like they are LIVE.
IF you think you know which side is less likely to be live, you favor the connection which makes the outer fuse contact less-live when fuse is blown and is being replaced. But IMHO this is a 40:60 bet (was in my old house). The proper procedure is to UN-PLUG THE DANG AMP!! before you mess with fuses.
In fact the plug-connection is WHY the white/black thinking used for in-wall wiring does not really apply to in-appliance wiring. We can always COMPLETELY dis-connect the electricity before working.
The most modern thinking is a 2-pole switch. Required in some countries. The general regulatory headache encourages use of a standard Power Inlet Module, with line-cord, switch, and often fuse all in one and component-approved. But it is a real pain to chop that funny hole unless you can spread punch-payments over many builds.
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PRR I can attest that without a punch that hole is fun fun fun. :sad2:
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I never thought about the fuse part of it....as far as changing them while plugged in......so if I knew the least live side , thats where the fuse would be, and the switch on the other....I talked to an electrician at work about it, and even tho his explanation was vague, it made more sense after re-reading PRR's explanation
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PRR post with double switch is excellent.
Put fuse on hot side, if single switch, also put on hot side.
With three wire system in US, switch on neutral, creates hazard. From a safety standpoint, we unplug, but not every one is safety minded, this really includes those who work under the hood. Just think, how people have linesman pliers or diagonals, with "holes" in the cutter portion. With switch on neutral, a significant portion of the amp is still hot just ready to go to ground if someone sticks screwdriver in the chassis. (Remember if the wall is wired correctly, that green /green-yellow wire and the white wire meet in the main panel.
Am I correct that some of the caps remain charged at a line voltage differential, if you put the switch on the neutral? if so, then another reason for switching the hot.
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Only England (as far as I can know) uses special attentions to the phase and neutral position on the outlets and special plugs that can't be reversed those plugs also has a protection fuse on it (that is fine)
Franco
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> Only England (as far as I can know) uses special attentions to the phase and neutral
The US has a standard pin-out. 2-pin plugs are polarized (one wide blade). 3-pin plugs have a standard layout. This goes back to the 1970s.
Both features are nuisances, especially on older gear. Adapters are available everywhere and can be used wrong.
In my experience it is often done wrong inside the walls. Good professional electricians get it right; also town inspectors often use a tester which indicates several of the easy faults. But many-many homes have DIY un-inspected wiring, especially in spaces like garages where guitarists hide from the family, also in rural areas where they live to avoid high housing cost and fussy neighbors.
I figure I do NOT know which side is "hot".
Further: my "neutral" is never dead-cold. I have several volts depending on the load on my too-long line from the street. This must be true (to lesser degree) for most "230V" countries which do not bring balanced power to houses.
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Thanks for the precisation PRR
do you mean this type of plugs ?
(https://upload.wikimedia.org/wikipedia/commons/a/ae/NEMA-AC-Power-Plugs.jpg)
if so, I don't understand how the 2 pin plug can be inserted only in one way (or I've misunderstand ?)
EDIT: Are you talking about this type of 2 pin plugs ?
(http://www.worldstandards.eu/WordPress/wp-content/uploads/electricity-tiles-type-A-200-px.jpg)
Franco
p.s.: A nice page about plugs and outlets
http://www.worldstandards.eu/electricity/plugs-and-sockets/ (http://www.worldstandards.eu/electricity/plugs-and-sockets/)
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Your EDIT: yes.
However a Polarized plug will not fit in a non-polarized outlet. Unless you force it. Lots of new plugs and old outlets.
I think the Germans got it right. Either side can be "hot", deal with it.
The only place it "could" make a difference is Edison-type screw-base light bulbs. The outer shell is not quite exposed when lamp is screwed in, but is exposed when you change a bulb. And you never really know if that is "line" or "cold". (The conductors and screws are brass/silver color, but nobody notices.)
IMHO the real answer is to go to plug-type lamps. Some early CFL lamps did have plug bases, utterly safe. But the market for Edison-screw lamps is huge, and these lamp sockets sometimes last many-many years.
There is a precedent. House fuses used to be Edison-screw. Same size 6A to 20A. A US Penny fit nicely in the bottom. Someone makes an adapter to a smaller screw-base, different sizes for different Amps. Won't fit a penny. Once installed it is very hard to get out. This forces future fixers to get the right fuse. But I have never seen a lamp-socket adapter to a plug-type lamp.
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Oh, rare to be seen but exists (on some Electronic Fair I've seen some)
(http://i00.i.aliimg.com/img/pb/861/673/510/510673861_515.jpg)
(http://g03.a.alicdn.com/kf/HTB1sYVCIXXXXXbKXpXXq6xXFXXXn/1Pcs-E27-to-font-b-GU10-b-font-Fireproof-Material-lamp-Holder-Converters-font-b-Socket.jpg)
Franco
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You gotta to be careful when changing a light bulb on a balcony for example. If you think you're safe because you have flipped the switch off, you may wake up at the hospital with your hair curled or pass away.
i have seen so many times a switch hooked up to the neutral. It works, but you have the hot side of line at the socket and if your bare feet are on a concrete floor or in a bathtub....ouch ! :cussing:
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In the US, most hardware box stores sell a device with three leds, that when plugged in, show whether the plug is wired correctly. For those of us who don't have roadies, that five dollar device is cheap insurance.
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yup....I got one......and I put the fuse and switch on the black wire.....because I have learned why its the best way.....the education never slows down here :icon_biggrin:
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here in Belgium we are free to switch hot and neutral around, like in many european countries. so all wiring has to deal with both options. and for the mains plug we combine the french (ground pin) with the german (ground on side contacts). so we have plugs with double ground connections that have a tight fit. makes me feel pretty safe :icon_biggrin:
(https://www.conrad.nl/medias/global/ce/5000_5999/5500/5520/5526/552646_BB_00_FB.EPS_1000.jpg)