correct cable for par 56

[djmatthill]

Just a quick one

 

Need to make up some single gang extension leads ( 13amp uk3 pin plug to 13A uk 3 pin socket) .

 

To use to connect some PAR 56 `s (500w) to the mains.

 

What should the cable be rated as amp wise.

 

Just to note there will be one par 56 per extension lead.

 

Whats the wattage - Amp maths ????

[niclights]

P=IV

 

I=P/V

 

500/230 = approx 2.2A

 

Or thereabouts, so not very much in other words. 1.5mm2 is most common available and more than capable!

[djmatthill]

so a 3amp 3 core cable will do the job ok ???

[niclights]

Yes. Make sure you use 3A fuse.

[gareth]

If you're using 13A connectors, you should really use 1.5mm^2 cable regardless of what you're plugging into the end.

[daemon]

Legally here in Australia as I imagine anywhere else that has (somewhat!) sensible electrical laws you cannot have a cable after a circuit protective device that is of a lower rating that said device. ie. If the outlet you are plugging into has a 13A fuse then the cable plugged into it must be rated for at least 13A. This is to protect the cable if a fault condition occurs.

 

Simple rule - Cable should be rated no less that the the rating on whatever it can be plugged into... irrespective of the load at the other end.

[Neil Hampson]

Legally here in Australia as I imagine anywhere else that has (somewhat!) sensible electrical laws you cannot have a cable after a circuit protective device that is of a lower rating that said device. ie. If the outlet you are plugging into has a 13A fuse then the cable plugged into it must be rated for at least 13A. This is to protect the cable if a fault condition occurs.

 

Simple rule - Cable should be rated no less that the the rating on whatever it can be plugged into... irrespective of the load at the other end.

 

Hence the design feature in BS 1363 (UK) 13A plugtops for interchangable fuses of different ratings. Remember the fuse is there to protect the CABLE, and only the cable so they need be sized accordingly. If the PAR56's are to be wired with 13A plugtops then yes fuse them to 3A, and remember to replace them with 3A. But if you plan to use a 15A Round pin plugtop (BS 546/A ?) then the cable should be rated at 15A or in accordance with the upstream protection (usually the dimmer fuse/MCB). Many people rate extensions at 10A as this is the output fuse rating of many dimmers are 6Ch x 2.4KW such as the ever popular Betapacks etc. but check your venues as some dimmers are coming in 3KW versions now, not 2.4KW.

 

Edit :- AFAIK; A PAR56 is 300W Max, not 500W

[tokm]

AFAIK; A PAR56 is 300W Max, not 500W

True if your only looking at the sealed reflector lamps, but if you were to use one of the reflectors with a gx9.5 lamp base in it, then you could put in a lamp with a rating upto 650w. T12 IIRC?

 

Just saying...

[Yorkie]

No point really bothering with thin cable; it's not as useful for other applications and if you want to use it for more sensitive kit, the voltage drop along thin stuff could unacceptable. Best to get some of this: 1.5mm^2 3core TRS

[adam2]

The OP clearly refers not to the fixed lead attached to a PAR lantern, but to extension leads for use with these appliances.

Whilst there is nothing unsafe in using 0.75mm flex with a 3 amp or 5 amp fuse in the plug, I would consider this to be poor practice.

In the real world to most people "an extension lead is an extension lead. If the fuse blows replace it with a 13 amp one. After all it says 13A on the plug doesnt it"

 

Unless the leads are to be kept locked up and only used by yourself, I would use 1.25mm or 1.5 mm flex and 13 amp fuses in the plugs, the lead will then be safe for any reasonable other use for which it may be required.

[Jivemaster]

While you will save cash by using 0.75mm^2 you will lose when you have to make the 13/16 cables later.

 

It's not safe to have a small flex in a 13a plug where the fuse may well get changed up next time.

[djmatthill]

Thanks guys , bought 6 amp 1.5mm cable to be on safe side as suggested. 3amp fuses also fitted and plug tops marked 3amp

[gareth]

Thanks guys , bought 6 amp 1.5mm cable to be on safe side as suggested.

I don't think you did. 1.5mm^2 cable is good for 15 amps. If the cable you've bought really is 1.5mm^2, then there's absolutely no need to down-rate the plugtop fuses to anything other than 13A.

[dbuckley]

Legally here in Australia as I imagine anywhere else that has (somewhat!) sensible electrical laws you cannot have a cable after a circuit protective device that is of a lower rating that said device.

 

Not the case in Oz and NZ; the 10A socket is protected at 20A, and you can plug in a table lamp with 0.5mm wire. The only notable exception are four ways (or five ways or three ways, but not two ways) which have an integrated 10A circuit breaker, to protect the cable upstream of the board.