Uk Electricain Help

Reply

  #1  
Old 06-23-04, 01:25 AM
Snape
Visiting Guest
Posts: n/a
Talking Uk Electricain Help

Hi guys, im currently a electrician in England, im moving to Ottawa next year and i have been studying alot of Canadian electrics via sites just brushing up on the cable colours and differences.
Ive noticed that you run both your power sockets (Recepticles) on the same circuits as your lighting, is this practical as in England lighting is on a seperate circuit usually 6A and Sockets (Recepticles) are on 20A - 32A.
Also does anyone know which saftey code book i will need to get and follow, and where i might buy a copy so i can start studying the regulations.

Will be greatfull for any advice that can be offered to me.

Thanks for all your help so far.
This is a really useful site aswell by the ways.
Ian Snape
 
Sponsored Links
  #2  
Old 06-23-04, 04:43 AM
HandyRon's Avatar
Member
Join Date: Dec 2001
Location: New York
Posts: 1,365
I am not an electrician in Canada, but this link below seams logical.
http://www.techstreet.com/cgi-bin/de...duct_id=931615
 
  #3  
Old 06-23-04, 06:16 AM
Member
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
Having lighting and receptacles share the same circuit works acceptably; after all, even in England they plug their floor lamps into the receptacle circuit. Sometimes one has problems with the lights flickering when large loads are turned on, and it is IMHO good design to separate lighting and receptacle circuits, but this is not required by code (US perspective here).

The really really big difference is that much less power is delivered by a single circuit, so there are more circuits in a comparable home. A UK ring main is often 32A at 240V...but the largest 'general purpose' circuit in a US home will be 20A 120V. Ring circuits are prohibited. Receptacles and plugs are not fused. Large appliances use 240V, but in the form of two 120V phases balanced about a neutral (or in some cases 208V in the form of two 120V phases in a three phase system)

The safety code varies considerably from location to location. In the US, the NFPA (a private corporation) publishes the 'National Electrical Code', which may then be adopted by the government in a particular region. Sometimes the government entity will amend the rules, sometimes they will adopt a particular edition of the rules, etc. I do not know what the Canadian equivalent is, but I do know that the rules are _generally_ the same, but with differences in many specifics.

If you want a site that explicitly discusses the Canadian electrical code from the point of view of the professional electrician, take a look at http://electrical-contractor.net/forum

-Jon
 
  #4  
Old 06-24-04, 02:14 AM
Snape
Visiting Guest
Posts: n/a
Talking Hi Guys

Thanks for the replys guys they were usefull. I got a few more questions that hopefully you will be able to help me with. Does anyone know where i can get hold of the calculations to work voltdrop and for working out services etc..
I would like to see if they are similar to ours in the Uk, here are some from the Uk.
For Voltdrop the calc would be Vc = mV x Ib x L / 1000
Where mV = Value from the IEE BS7671 Regs book
Ib = Design Current Of The Circuit
L = Length Of The Run

We work out the Protection device (Fuse) by taking the
Design Current(Ib) and Choosing a Fuse that is > or = to the design current.
We would the work out the correction factors of the circuit by looking at
Ambient Temp(Ca), Grouping Factor(Cg) Thermal Insulation(Ci) this would give us the operating voltage of the chosen cable to see if it complies to regulations.

Does any of this sound comparable to the methods used in US or Canada, to work out cable and protection devices.

Also do you apply diversity to your circuits where you say that if a cooker is rated at 12Kw that is totally uinlikely that you will use all of the power in one go so you apply diversity so that you can reduce the cable size etc..

In our circuit we call circuits that branch off from a recepticle a SPUR, and you can only have one spur from ever recepticle on the circuit. But from what ive read and seen its seems that you can branch off as many as you like on your circuits.

One final question i saw a question on this board where a guy said that he was having a load of 110A in a subpanel, but if he ran the supply as 240v then the load would be 55A, but all his breakers still added up to 110A, i know that if you increase the voltage ampage halfs and vice versa, but it didnt make sense to me, help haha

Sorry for the questions im just trying to get as much insite and information into the ways of the US & Canadian Electrican so that i will be good grounded in info and ways. For when i finally get there.

Thanks for your information in advance.
Ian
 
  #5  
Old 06-24-04, 04:55 AM
Member
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
You are going to have to buy and read the appropriate code book, since the devil is in the details, and so many of the details are so different. But in general:

1) Voltage drop calculations are essentially the same, although the scaling factors that you use are probably different. Voltage drop is simply ohms law, so you have to figure out the resistance of the conductor, and multiply by the current flowing. Resistance is usually tabulated in ohms per 1000 feet of conductor, so the equation looks essentially the same as the one that you posted. In the US NEC, there is no specified _required_ table of conductor resistance; you are expected to use the correct resistance for the conductor in question. However there is a table of conductor resistance in an appendix at the back of the NEC. The other difference is that you are not _required_ to use the design current; instead it is _suggested_ that you design to limit voltage drop to certain values in operation.

3) Article 220 Branch-Circuit, Feeder, and Service Calculations is all about load diversity and real expected loading for various combinations of possible loads. You can install 1000s of amps of possible load, but the feeder to a panel with this load need only be sized for the _calculated_ total load.

2) (Numbering matches the order of your questions) For figuring the protective device, the process is similar; again in the US NEC things get a bit Byzantine, with different requirements for different sorts of loads, spread throughout the code. But depending upon circumstances, in general, the ampacity of the conductors and the rating of the OCPD must exceed the design current as calculated in Article 220. In circumstances where single loads or continuous loads are supplied, there are many cases where the conductor ampacity and the OCPD rating must be at least 125% of full load. See article 310 of the NEC for conductor sizing, and article 240 for OCPD sizing.

4) Essentially _all_ circuits in the US are done as SPUR connections, with no limit to the number of branches. But we use OCPD rated to the conductor size; if I recall correctly, OCPD on a ring circuit is 2x the conductor ampacity, because current can take two paths to the loads.

5) Service in the US is usually 240V supplied as two 120V phase legs balanced around a neutral. You can tap loads either between a phase and neutral, _or_ between the other phase and neutral. For large loads you tap phase to phase, and have 240V supplied to the load. If you have a bunch of different loads in a panel, you try to arrange them so that about half of the loads are on one leg of the supply, and half on the other. As I recall, in the UK you usually only have one phase leg from the supply transformer...but different houses are balanced across the transformer.

-Jon
 
  #6  
Old 06-28-04, 02:00 PM
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 5,677
ontario esa

If you are moving to Ottawa then you fall under the Ontario Electrical Safety Authority.

Here is alink to their web site.
http://www.esainspection.net/
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes