NVR or DOL,

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

squib

Established Member
UKW Supporter
Joined
27 Nov 2009
Messages
453
Reaction score
47
Location
Shrops.
After reading the NVR thread I have a question that I wanted to ask and not hijack the thread... I have just put a more powerful motor on my pillar drill , the motor is a 3/4 hp Brook Compton and the drill in an old cast machine,not large and bench mounted. so my question is do I need to use a DOL switch or could I get away with a decent NVR one instead.The cheapest DOL switch works out to be about £45 or more delivered whereas the NVR is less than half and would be easier to mount.
Any advice from those in the know gratefully received.
 
So long as the NVR can handle the amperage use that. 1/2kw is not a big motor by any stretch so I'd be very surprised if there was an issue - my router is 2kw and has one so does my 4kw table saw.
 
A NVR switch is just that it switches the power off with the off button or if power is interupted whilst the machine is in use it will stop and not restart when the power comes back on.
A dol starter though genrally has current protection built in so protects your motor from overload
you can get dol's with or without NVR
Ian
 
If you were talking about a motor rated at say 3hp or 2Kw and above, then a proper motor starter might be sensible. The starter is there to protect the motor from damage as opposed to the circuit breakers in your fuse board which are there essentially to protect the fixed electrical wiring and to cut the power in case of a short circuit. If the motor is cheap enough that you can afford to replace it, then you may feel that spending a fair chunk of its cost for the overload features of a proper starter isn't worth it to you. Personally I wouldn't on any motor small enough to run off a 13A, or perhaps a 16A plug.
It's a different story when you're talking about motors that cost hundreds, even thousands of pounds which to us as woodworkers would be large, but small enough to be disposable by the standards of industry.

Please note that the NVR function is really about protecting people, not the motor, which is why these are important even on machines with small motors if there's any danger that someone could be hurt if the machine restarted when not expected. Saws, drills, planers, sanders, etc yes. Grinders too, though a lot of them used to be made without NVR switches. Extractors I'm less convinced as you shouldn't have your body parts anywhere dangerous without unplugging it first.

If I was in business, I'd play safe and if a machine was built with a NVR or DOL starter, I'd make sure to replace like with like to maintain the level of safety the manufacturer designed.
If I was upgrading something, I'd seek advice just as you've done. I'd go to a professional for advice if this was for my business and you might ever have to justify something to HSE.
 
Thanks all, I will fit a NVR as its a drill and not an especially dangerous piece of machinery.
All my bigger kit have DOL starters.
 
PS.....err...changed my mind as I have found that a decent NVR of the right power is about the same as a small DOL so have ordered one. Thanks once again.
 
Back
Top