What resistor is this?

[laserpon3]

I am familiar with resistors but.
On dave's video of the lab power supply design part 3 he uses some weird big white resistors. [0:38]
https://www.youtube.com/watch?feature=player_detailpage&v=8-qar5vgnbc#t=38s



I have also seen this resistors being used in another lab power supply making video:

What type of resistor is this?
I can't seem to find them or find a proper place to buy them (as I don't know what they are).

Why are these used for dummy load instead of the more common resistor types? less heat? more durability? higher resistance?
From what I believe, dummy loads are a lot of resistors connected to eachother. I'm not sure, but searching dummy load resistor doesn't give me anything looking close to this.

[Psi]

What type of resistor is this?

It's a "ceramic wirewound resistor". They're the next step up from a normal resistor in terms of power handling.
The small white ones start at around 5W and some of the larger ones are 40W+

I can't seem to find them or find a proper place to buy them (as I don't know what they are).

Digikey have them in the  "Through Hole Resistors" section.
Just parametric sort based on above 5W and you will find lots of them.
eg http://www.digikey.co.nz/product-detail/en/SQP20AJB-1R/SQP20AJB-1R-ND/1680006

Why are these used for dummy load instead of the more common resistor types? less heat? more durability? higher resistance?
From what I believe, dummy loads are a lot of resistors connected to eachother. I'm not sure, but searching dummy load resistor doesn't give me anything looking close to this.

More common? those kind of resistor are really common.
There are other types as well. Like these more expensive mountable ones, some of which can handle 100W if mounted properly.

[nadona]

I think they call it cement resistor. Maybe you get the clue by reading this paper. http://www.yageo.com/documents/recent/Leaded-R_PSP_2011.pdf

[laserpon3]

Thanks guys!
This answered the question for me!

[SeanB]

Wire wound resistors in a ceramic boat. Common at high power, as the case is an insulator even when red hot. Most round wirewound ones with a dip coat are conductive through the coating when they get hot enough.

[T4P]

And there are massive/powerful wirewound ones that are green in colour and you can see the wound wire on the substrate! But they are quite dangerous ... exposed wire, who wants some of that?
Usually they look like that

But ...
sometimes they come like that

[Short Circuit]

... But they are quite dangerous ... exposed wire, who wants some of that?

Most resistors have exposed wires... Big ones no different than your standard 1/4W PCB resistors 

And you want to shield them from unintended touching anyway, these things can get hot, very hot.
Operating temperature range up to 225 degrees (TE range), much hotter during short term overload condition.
You don't want people to touch that by accident.

[SeanB]

The conductivity is a problem if it is mounted in a metal clamp and it gets hot, which then causes a leakage to the clamp of the resistor voltage. It is possible to have enough current flow to make it go into thermal runaway.

[IanB]

What type of resistor is this?
I can't seem to find them or find a proper place to buy them (as I don't know what they are).

If you are in the USA (you have no location in your profile) then go have a look in RadioShack or maybe Fry's. You will find resistors looking just like that in power ratings of 5 W, 10 W or 20 W.