In the US, parallel conductors are not allowed in the smaller sizes, and connections that depend on solder are not allowed for service conductors. Also, if this was allowed, wouldn't it be a lot more material and labor than just using a single wire of the correct size?
Just for the techs who wonder why solder isn't allowed. When a connection gets hot the solder would melt and create all kinds of problems.. Solder has a much lower melt temp than copper. That's why in higher load carrying circuits we use crimp or compression type connectors.
I read in sci.engr.electrical.compliance that PJx wrote (in ) about '30A wiring advice', on Wed, 24 Dec 2003:
I would expect soldered connections in terminal blocks to be banned, because the solder creeps under pressure and the clamping screws loosen. Soldered connections are not allowed in Europe.
It's posted in four newsgroups, including sci.engr.electrical.compliance , where people know about wiring codes.
Here in Canada we have rule 12-108 which has 7 rules for parallel runs. One of these rules is that the condustors be 1/0 or larger. My guess as to the reason for this rule: parallel runs have certain risks ie if one run becomes lose or disconnected the remaining run(s) may overheat, therefore, don't use'm where you don't need'm.
230.81 Connection to Terminals. The service conductors shall be connected to the service disconnecting means by pressure connectors, clamps, or other approved means. Connections that depend on solder shall not be used.
310.4 Conductors in Parallel. Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, neutral, or grounded circuit conductor, shall be permitted to be connected in parallel (electrically joined at both ends to form a single conductor).
I agree with your comments about soldered connections in terminal blocks. However, soldered (or crimped or brazed) connections are required in the UK if the join will not be accessible for maintenance and inspection.
One way which is acceptable to do this is to use screw terminals, and then also solder the conductors to the terminals. Solder creep is not an issue in this case. However, most commonly, such connections are done by crimping -- soldering is a skill which installation electricians would rarely have.
Ummm, well, no, not exactly. It has more to do with solder's lack of mechanical strength. The melting point of solder, while indeed well below that of copper, is well *above* the temperature rating of any conductor insulation that I've ever heard of -- IOW, the insulation would burn off of the conductor
*long* before it got hot enough to melt a soldered connection.
-- Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
Yes Minister Series Quotes from the dialogue "The argument that we must do everything a Minister demands because he has been 'democratically chosen' does not stand up to close inspection. MPs are not chosen by 'the people' - they are chosen by their local constituency parties: thirty-five men in grubby raincoats or thirty-five women in silly hats. The further 'selection' process is equally a nonsense: there are only 630 MPs and a party with just over 300 MPs forms a government and of these 300, 100 are too old and too silly to be ministers and 100 too young and too callow. Therefore there are about
100 MPs to fill 100 government posts. Effectively no choice at all."
replying to John Woodgate, Albert wrote: John, THANK you for yr Comments. can you tell me when cable ratings are calulaged for say 10mm2 twin and earth do they apply to the WHOLE cable, or just per single Conductor? If at all poss please Emil your reply. Many many thanks. albert
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