British-Canadian differences

[Goldwing]

I am hoping that there is someone who uses the forum who would be able to help me to understand the different terminologies and materials used on British wiring systems compared to Canadian. I have been a journeyman for 35 years and will be part of a team that is traveling to Mozambique in late February or March. While on site it is my responsibility to educate a few nationals about electrical theory and help to give them the basic skills to maintain the facilities electrical systems. I am not concerned about the theory however the wiring terminologies, methods, and materials differ from the ones here in Canada. There is a vehicle repair facility that is being built that needs power as well as various problems with other parts of the sytem with regard to voltage drop and balanced loading of the three phase gen sets. (The sites power is supplied by two privately owned generators)

I am new to the forum and not sure how all the parts of it work so we could use email for communication if need be.

I am looking forward to some constructive advice and information. Our methods, materials, and regulations are somewhat different but I am hopeful that you will be able to help me overcome the obstacles. :21:

Thanks

 

[Goldwing]

Just looking back over the different types of installs . . . I will take a set of drawings indicating the various types and compare how the gens and service switches etc are grounded. Also how the neutral is dealt with. I am hopeful that it will not be a mix due to foreigners like me doing stuff there way. I have run into that in Mexico on a mission site.

 

[Richard Burns]

Bathrooms are a bit strict here but you must have RCDs (not GFCI) rated at max 30mA protecting all final circuits (Not branch circuits) in the bathroom.

The "zones" would be best explained if you were to see if you could look up the diagrams somewhere on the web, however as a general overview in​ a bath/ shower tray is zone 0 12V SELV with no switches all minimum IPX7
Above the bath/ shower tray up to 2.25m us zone 1 IPX4 or IPX5 if water jets only 12V SELV switches can use up to 25V SELV power but LV for showers, fans, lights and bath pumps and some other stuff.
From bath / shower edge to 600mm out and up to 2.25m is zone 2 IPX4 (5) SELV only switches and separated shaver sockets, other than that general BS7671, outside zones general BS7671 but should be suitable for damp environments and no 230V sockets allowed within 3m.
Lights over showers are standard here so long as they are IPX5.
Meteor electrical on the advertising side bar is a general electrical wholesaler who are forum sponsors so may be useful to look through.

 

[Goldwing]

Oh God . . . relegate me to the "stupid" thread on the forum . . . I never even looked at the side bars!

 

[Engineer54]

Thanks all for input on the feeders. I am aware of the necessity for same type, length etc of parallel runs so I had that in my mind anyway. I think I am getting the overall picture a lot clearer in this area now. Are your protection tiles something that is readily available or can I get away with just burying the cable deeper? No doubt I may run into problems ordering the correct materials for the whole job due to things like, quantity, plus any little twists that I will not see until I get there. It will not be like I can just run to the wholesalers and get more or different materials.

If your working to any specified regulations, no matter how vaguely worded, you'll need to use protective tiles (i'm pretty sure your regulations would call for these too, as it's pretty much universal) Made for purpose tiles have a indented warning on them and come in various sizes, dependant on how many cables they are covering, but in reality you can use any of the smaller garden/street paving slabs if you like.

I will follow with a few questions about the branch circuits. I see that the rules for your bathrooms are different then ours. I was going to install a GFCI protected outlet (if you have such a thing) or a current limiting transformer approved for shaver along side the sink with a light above the sink.

The UK is way over cautious as far as allowing RCD protected socket outlets are concerned. We do have 30mA RCD socket oulets, but even they can't be used in zones 1 and 2. Daft really, the rest of Europe have been installing outlets in bathrooms even before RCD's were common place!!! We do allow SELV transformer shaver outlets near sink locations and there is no problem with light fittings above the sink, but must be IP 44 or above....

The shower stall could use a downlight, as it is walled in on three sides. I assume that there is an approved fixture for that type of location with a shower trim. I was going to locate all of the switches outside of the room as you seem to have some stringent rules with regard to areas around the shower or tub. Is it common over there for a light above the shower stall?

You'll have to ask others here as to lighting in shower cubicles, but as far as i know again Min IP 44 but there may be a height restriction. All lighting in shower/bathrooms by the way, to be RCD protected. You can use a ceiling mounted pull switch within bathroom areas.

Thanks again gentleman

No problem, maybe someone here, will at sometime want to know a little about Canadian electrical codes, or the way you go about things. So perhaps you can then return the favour, so-to-speak!! lol!!!

 

[Goldwing]

Not really experienced at this sort of install but I believe the following would be correct for BS7671 wiring regualtions compliance.

Voltage drop permissible is 3% for lighting and 5% for non lighting

Richard, I was just reviewing some other information on voltage drop. It indicated that "•The new regulations now provide different voltage drop values for installation supplied from a public supply and private supply (i.e. Own generation). For a public supply the maximum values are 3% for lighting and 5% for other uses, for a private supply the maximum values are 6% for lighting & 8% for other uses." Were you referring to the voltage drop end to end for public supply previously? As the work I will be doing is on a private gen am I able to use the 6%? I am also assuming that there is no difference in voltage drop requirements for domestic and this shop with a small mezzanine that could be classed as domestic but is otherwise industrial.

Cheers

 

[Richard Burns]

the values I gave were for a public supply.
A private supply is permitted to have the volt drop values you gave (6% and 8%) at the origin, however final circuits (branch circuits) must have the Vd of 3& and 5% so there is really no difference except for the supply voltage.

Other things:
For long circuits the Vd can be increased to up another 0.5% for a 200m circuit (0.005% per meter if >100m)

Also the product standard for equipment may specify a greater voltage drop is permitted;
If the volt drop does not impair the safe functioning of equipment.
These two would be allowable if proved, however the values of 3 and 5 percent can be used to avoid any need for proof since it is deemed that they are met if the Vd is 3 /5 percent.

Transient higher volt drop is also allowed for high inrush currents so long as it meets the product standard or manufacturers instructions.