# Current inrush limiter?



## twentysix by twentyfive (9 Feb 2021)

A question for the sparkies out there if you will please.

I have a 2 kW electric chainsaw which trips the 16 A circuit breaker which feeds the garage at start up. What sort and where can I source a suitable current inrush limiter? Preferably just one I can plug the chainsaw straight into but I'm OK for some simple soldering if that keeps it simple and costs down.

My googling suggests I may require 6x the average load current for startup - so 48 A if I calculate correctly. Would I get away with plugging into a 32 A circuit breaker protected circuit? I guess it depends on the time required for the breaker to trip compared with the time the surge lasts?

TIA


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## irw (9 Feb 2021)

A different type of 16A breaker might be the correct way to go about this...
You've probably got a Type B at the moment (as indicated below by the 'B16'):






A Type C will give you a bit more 'surge' headroom.
See https://uk.rs-online.com/web/generalDisplay.html?id=ideas-and-advice/mcb-guide for info


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## twentysix by twentyfive (9 Feb 2021)

Thanks @irw . Mine are all Type 1 breakers which I find (via Google) are all ancient now. Hopefully I can find a Type C which fits in the Consumer Unit


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## irw (9 Feb 2021)

I see! By way of a disclaimer, it might be worth consulting a suitably qualified electrician, unless one comes along here in the meantime. Whilst I 'do' temporary electrics as part of my normal theatre jobs, domestic and installs (and the exact rules around them) are not my normal area.


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## twentysix by twentyfive (9 Feb 2021)

irw said:


> I see! By way of a disclaimer, it might be worth consulting a suitably qualified electrician, unless one comes along here in the meantime. Whilst I 'do' temporary electrics as part of my normal theatre jobs, domestic and installs (and the exact rules around them) are not my normal area.


No worries . 

I went along to my local (very good supplier) but they don't do the compatible part I need. Advice was to internet it. I've pinged the compatibility question to a few potentials so am waiting to see.

Any knowledgeable folks know if a Type 2 is the equivalent of Type C? As I think Types 1 and B are equivalent... Or are they?


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## twentysix by twentyfive (14 Feb 2021)

After much searching I was advised that Type C breakers are not compatible with my Consumer Unit. I tried to run the chainsaw with a very long rolled up extension lead instead. It works a treat. I know that the coiled up lead might get hot so I check for that. So far so good 👍


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## irw (15 Feb 2021)

twentysix by twentyfive said:


> After much searching I was advised that Type C breakers are not compatible with my Consumer Unit. I tried to run the chainsaw with a very long rolled up extension lead instead. It works a treat. I know that the coiled up lead might get hot so I check for that. So far so good 👍



Really, really not a good idea...Most roll up extension leads I've come across are rated to about 700w max when coiled, and rarely 13A when uncoiled- you're risking fire, and electric shocks. I know you said you checked it, but these things have a habit of working seemingly happily until they don't, at which point they can become very dangerous very quickly. Every time you start the chainsaw, you're going to be stressing the extension coil way beyond it's design limits, and by pulling a constant 2Kw through it coiled up, it will potentially lead to it failing in a dangerous manner when used in a different situation, or by someone else in your household.

Depending on the cabling size and specification to the garage, maybe you could see if the 16A breaker could simply be replaced by a 20A, or as you initially suggested, a 32A breaker if you can't get a type C 16A? I suppose the proper way to deal with this if you can't get a like-for-like type C that fits in your existing board would be to simply have a 2nd small (more modern) consumer unit installed next to the original.


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## slowmotion (15 Feb 2021)

twentysix by twentyfive said:


> No worries .
> 
> I went along to my local (very good supplier) but they don't do the compatible part I need. Advice was to internet it. I've pinged the compatibility question to a few potentials so am waiting to see.
> 
> Any knowledgeable folks know if a Type 2 is the equivalent of Type C? As I think Types 1 and B are equivalent... Or are they?


Have a look at Table 3.3 in this link........
https://www.tlc-direct.co.uk/Book/3.6.4.htm
Type C and Type 3 have similar tripping characteristics, both allowing ten times the rated current for short periods. (I can't find the time/current tripping characteristics graph right now). I don't know the make or model of your consumer unit, but even if it's obsolete I'm pretty sure you could find a spare second hand one on Ebay somewhere. I did for an obsolete Volex CU a few years ago and bought another as a spare.


Edit: look here....
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=Type+3+MCB&_sacat=0
There's probably one that will suit you.


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## twentysix by twentyfive (6 Apr 2021)

irw said:


> Really, really not a good idea...Most roll up extension leads I've come across are rated to about 700w max when coiled, and rarely 13A when uncoiled- you're risking fire, and electric shocks. I know you said you checked it, but these things have a habit of working seemingly happily until they don't, at which point they can become very dangerous very quickly. Every time you start the chainsaw, you're going to be stressing the extension coil way beyond it's design limits, and by pulling a constant 2Kw through it coiled up, it will potentially lead to it failing in a dangerous manner when used in a different situation, or by someone else in your household.
> 
> Depending on the cabling size and specification to the garage, maybe you could see if the 16A breaker could simply be replaced by a 20A, or as you initially suggested, a 32A breaker if you can't get a type C 16A? I suppose the proper way to deal with this if you can't get a like-for-like type C that fits in your existing board would be to simply have a 2nd small (more modern) consumer unit installed next to the original.





slowmotion said:


> Have a look at Table 3.3 in this link........
> https://www.tlc-direct.co.uk/Book/3.6.4.htm
> Type C and Type 3 have similar tripping characteristics, both allowing ten times the rated current for short periods. (I can't find the time/current tripping characteristics graph right now). I don't know the make or model of your consumer unit, but even if it's obsolete I'm pretty sure you could find a spare second hand one on Ebay somewhere. I did for an obsolete Volex CU a few years ago and bought another as a spare.
> 
> ...


 Just coming back to this. Thanks both. I haven't been using it much at all. My wiring to the garage is 16A compatible (a spur from the main board to a smaller board in the garage which does a split for lighting and mains circuits. The Type3 that slowmo linked to is a compatible one for the main board which was the one that tripped. Sitting here typing I'm not sure what sort of breaker is an the garage board but it isn't as old. So I'll off and get a Type 3 and check the garage board too.

Cheers


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