Electricians usually know how to wire the lights that they've always used, and are not lighting experts. It's great that you have the help to wire the lights, but take his advice with a grain of salt. You need to decide what kind of lighting you are going to use in the fixtures before you decide what size they will be. Halogen recessed lighting provides a lot more light, so you can get away with 4" cans and still have lots of light. The down side to halogen is that it is HOT HOT HOT and there's no way I'd use it unless I was in a Northern climate. Incandescent is being legislated out everywhere, and no way I'd lock myself into an obsolete system. There's fluorescent and LED available, and each has their plusses and minuses. I suggest you go to a lighting store and view your options in person and have a lighting designer look at your floor plan and see what they suggest. You'll get exactly what you need for your location and design, and it's usually free if you purchase the lighting from them.

6" cans with flood bulbs have the largest spread (the cone-shaped beam of light) of all. The higher the ceiling the spread grows as well, because the base of the cone grows proportional to the height given that the same angle is maintained.
Based on aesthetics alone, I used 5" cans in my ceiling, and pairs of 4" cans above the sinks. I'm very happy with the amount of light. The cans were placed no more than 6' apart with my 9'9" ceiling ht. When finalizing the exact placement, I tended to center the cans on centerlines of cabinets/appliances for consistence of shadowing.
Casey

We had our 6 inch cans taken out as they were just too bright for me. We don't have ten foot ceilings however. I hope to take out the other large cans in the living room and put in the smaller ones. I like the warmer feeling of softer light.

We used 6 inch cans. My husband (general contractor but not a lighting expert) recommended we go with 6 and I really didn't care. We bought them and then I did some reading and it seemed like the trend was moving towards smaller cans so I panicked briefly. But we went ahead and installed the 6 inch cans and I love them. We have a small kitchen (approx 11x13) and 8 foot ceilings - we used 6 of them and I think it's the perfect amount of light, they don't look too large or bright for the space. I think it's a matter of personal preference - can your electrician bring a few sizes for you to see?

EccoBuzz, thanks for letting us know that you used six 6-inch recessed cans for your small kitchen since my kitchen also only has 8 foot ceilings and approximately 10 X 14 in size so is close to the size of your kitchen. I like very bright light so I am wondering if I should also go with the 6" cans despite the trend being toward smaller cans.

We have 7 1/2' ceilings and went with 3" cans for our recent small kitchen reno.
I'm attaching a link below.
We're happy with our decision.
But, you've got 10' ceilings so 6" cans would be better.
The smaller the can the more cans you need.
We used 12 cans in an 8x12' space.
You should seriously consider the reply from live_wire_oak with regard to newer lighting technologies.
You'll get your best information if you cross post this on the GW Lighting Forum.
The folk over there are very knowledgeable and helpful.

Here is a link that might be useful: Small Kitchen Reno

If you want to retrofit with the LED inserts in the future as they become cheaper, it will be a lot easier and cheaper with 6" cans.

We just finished installing 4" cans with the retrofit LEDs in our kitchen with a 9' ceiling. It is almost too small and I think that there could be a smidgen more light (but we haven't connected all the task/accent lighting yet). I think 5" would be absolutely perfect for 10' ceilings.

ditto scrappy25 -- I started out wanting smaller ones, but I'm finding that 6" gives me a lot more options. And you should be able to get whatever brightness and color temperature you want through bulb choice.

Despite the trend to go smaller, I am thinking I want more light and want to go with the 6" cans. I have talked to a few electricians and hope to talk to another one. Today's electrician is trying to push me to go to Halogen lighting since I love the 100 CRI and the 2950K color spectrum but I am still not sure if I want the heat unless I go with low voltage with the 4" size he recommends but then I will need 10 lights he says with 50 watt bulbs and that is expensive at $175 a piece plus the cost of the switches and dimmer for my little 10 X 14 kitchen plus I may want to change out the outdated light over the sink that did not fit the Cree LED.

The other electrician I called today says he does not like the light of LED and will visit after I bring home a Par30 75 watt bulb to try out the light of and then call him tomorrow. I looked up and it is 2950K temperature color with 100 Color Rendering Index (CRI). It sounds so hot!

I found LED's with a 285OK and 92 CRI but they fit into 4" cans.

Since a lot of the Cree lights are 6", I have a feeling 6" will still be here to stay despite the trend going to smaller sizes.

I like 6 inch because I think it will be easier to retrofit later on to LEDs. I also like that you can use fewer cans for optimal light. I don't care for the swiss cheese effect of having to use more can lights. I think less is more when it come to ceiling holes.

I put in 4" fixtures - MR16 bulbs, which you can buy LED replacements for today, so guaranteed you'll be able to do it in the future when LED's become more prevalent and economical.

I have 9 foot ceilings, and the pics below show how the lights wash on the cabinets, which go all the way to the ceiling. They can be angled/pointed in whatever direction you feel like.

Personally I don't like large recessed fixtures and I've been putting these smaller retrofit units in everywhere (made in Canada Contraste lighting CA2000D fixtures, not cheap made in China Home Depot specials).

In my 10x14 kitchen I put 10 of these fixtures around the perimeter about 10-12 inches out from the face of the upper cabinets, which allows me to angle them slightly towards the cabinet if I need to, in order to wash the face of the cabinet and light the counters. I also put 19 dimmable LED pucks inside the cabinets and for counter lighting on 2 switches - one for inside the upper glass cabinets and one for the counter lighting.

I have 12' ceilings with 6" cans. Probably you want to look at the wattage that each size/fixture is rated for. I think mine take 60w or 75w bulbs. If I could get the same wattage in a 5" it would look better aesthetically and work just as well.

I've tried various halogen, incandescent and fluorescent bulbs. The GE Edison halogens provide the best light to my eyes.

TorontoTim, I love your lighting and cabinets! First what bulb and wattage is in the MR16? Is it a low voltage 50 watt Halogen or a Line Voltage Halogen? What is the light spectrum K used and CRI (Color Rendering Index) used?

What white is your cabinets since it is so beautiful?

chiefneil, Thanks for letting me know that you like the GE Edison Halogens. Any pictures?

The only ones I have showing the lights are the somewhat infamous photos of when I was switching over from white trim to clear alzak. The electrician (a lighting specialist who talked me into the switch) was replacing my CFLs with Edison halogens at the same time.

I'm going to preface the photos by saying that showing differences in lighting with photography, especially with consumer-grade equipment, is tricky and often misleading. In the first photo with the CFLs the camera appears to have picked up on the glare and adjusted the exposure down, resulting in a darker photo.

This first photo has my CFLs in white trim. The two bulbs that appear to be out are actually the new Edisons in alzak.

Here's the finished job with all Edisons and clear alzak. The lights are still on even though they appear to be off.

Chiefneil, I love the clear alazak! The light it gives is better wit no glare and they do not stand out! What size are they? What wattage bulb? Are these inline or low-voltage? I love your dark cabinets and the gold walls!

Sorry meant alzak! I will check back to find out more information about your recessed lights that seem to fade into the ceiling. Chiefneil, your kitchen is looking very nice and warm.

Lynn, I checked the box and the bulbs are GE Edison 75W PAR30L. The cans are 6", regular line voltage.

I was originally going to put a chandelier over the island, but the cans put out a ridiculous amount of light so I never got around to it.

Chiefneil, I just checked out the bulb and it has a 2830K which sounds like a nice color with 100 CR, 60" spread, and 1100 Lumens for the 75Watts! I think I will go with Halogen and I hope they do not discontinue Halogen bulbs or at least a LED will fit in the sock if I made the investment for the 6" regular line voltage cans for the nice light. Thank you!

Lynn - sorry for the delayed response.

The bulbs are line-voltage 50w halogens. I used the low-voltage in my bathroom reno 3 years ago and the fixtures hum. Everyone says they shouldn't, but they do. I have them on Lutron digital LV dimmers, and that may be the issue - I might try a mechanical LV dimmer to see if that resolves the hum in the bathroom, but I've since moved back to using nothing but line-voltage recessed lights. Saves me money on the fixtures and the dimmers.

The cabinets are good old BM Cloud White, which was arrived at after weeks of having every shade of white large BM chip taped up to our walls to see how it looked in all lighting conditions.

I put one LED puck in each set of upper cabinets centered, but in the full glass cabinets I put 2 fixtures in to ensure thorough lighting carried down through the glass shelves. They're all on dimmers as well.

The LED pucks are 'warm', around the 3500K mark I think. I got them through LED Lights Canada in Edmonton for about $20 each which was cheap compared to many sources.

I couldn't bear the thought of using hot halogen/xenon lights inside my painted cabinets, and the counter lighting is boxed in - not just screwed to the underside of the cabinets. So heat was a major factor in spending the extra $ to go LED.

TorontoTim, thanks again for letting me know about your lighting. I have another electrician coming by tomorrow who seems to know about CRI and light spectrum ratings while most electricians seem to not know.

one of our biggest mistakes in our kitchen was following the smaller trend and using 4" cans. They can only take 50 watt bulbs because of the housing. before we put the housing in, we had 75 watt bulbs in there and the lighting was perfect. but when we put the housing in we had to change out the bulbs to 50's, and if I would have known that, I definitely would have used 6" cans. don't know where that trend came from or why we followed it. but now we're stuck with it. Also, we have average height ceilings and it's still not enough light for me. Hope this helps.

The electrician is stuck at a job and will not be able to come by until tomorrow night.

Thank you squigs for letting us know that you wish you went with the 6" cans.

It's time to update this post (and solicit new comments) for 2019. I just put in new traditional can lights and can no longer buy incandescent indoor flood lights. I had to switch to dimmable LEDs.